2022
Davide Lengani Dario Barsi, Daniele Simoni
Analysis of the Loss Production Mechanism Due to Cavity–Main Flow Interaction in a Low-Pressure Turbine Stage Journal Article
In: Journal of Turbomachinery, vol. 144, no. 9, pp. 091004, 2022.
@article{nokey,
title = {Analysis of the Loss Production Mechanism Due to Cavity–Main Flow Interaction in a Low-Pressure Turbine Stage},
author = {Dario Barsi, Davide Lengani, Daniele Simoni, Giulio Venturino, Francesco Bertini, Matteo Giovannini, Filippo Rubechini},
url = {https://asmedigitalcollection.asme.org/turbomachinery/article/144/9/091004/1134931/Analysis-of-the-Loss-Production-Mechanism-Due-to},
doi = {10.1115/1.4053745},
year = {2022},
date = {2022-09-01},
journal = {Journal of Turbomachinery},
volume = {144},
number = {9},
pages = {091004},
abstract = {In the present work, URANS simulations are presented to describe the unsteady interaction process between the flow ingested/ejected from a cavity system and the main flow evolving into a low-pressure turbine stage. Particular care is posed on the analysis of the loss generation mechanisms acting outside the stator row and in the rear part of the axial gap separating the cavity flow ejection section and the leading edge plane of the downstream rotor row. The simulated geometry reproduces a typical engine cavity configuration, with upstream and downstream rotor rows reproduced by means of moving bars. Experimental results have been used to validate the simulations. These experimental data cannot explain and quantify alone the overall interaction process between the cavity flows and the main flow. The results of a simulation made by removing the domain of the cavity have been employed in order to better highlight and quantify the effects due to main flow and cavity flows interaction on total pressure loss. A deep inspection of the loss amount along the axial direction makes evident that losses generated in the vane row are basically increased prior to entering into the downstream rotor bars, due to cavity main flow interaction.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Bellucci J Cozzi L, Giovannini M
Towards the development of an advanced wind turbine rotor design tool integrating full CFD and FEM Journal Article
In: Journal of Physics: Conference Series: Torque 2022, no. Conf. Ser. 2265 042050, 2022.
@article{nokey,
title = {Towards the development of an advanced wind turbine rotor design tool integrating full CFD and FEM},
author = {Cozzi L, Bellucci J, Giovannini M, Papi F, Bianchini A},
doi = {10.1088/1742-6596/2265/4/042050},
year = {2022},
date = {2022-06-01},
journal = {Journal of Physics: Conference Series: Torque 2022},
number = {Conf. Ser. 2265 042050},
abstract = {Large, highly flexible wind turbines of the new generation will make designers face un-precedent challenges, mainly connected to their huge dimensions. To tackle these challenges, it is commonly acknowledged that design tools must evolve in the direction of both improving their accuracy and turning into holistic, multiphysics tools. Furthermore, the wind turbine industry is reaching a high level of maturity, and ever more accurate and reliable design tools are required to further optimise these machines. Within this framework, the study shows the development of an integrated platform for blade design integrating 3D CFD flow simulations and 3D-FEM structural analysis. Artificial intelligence techniques are applied to develop an optimization procedure based on the proposed tool. The potential of the new platform has been tested on the well-known test case of the MEXICO rotor, for which an optimization of the blade design has been carried out. Exploring a design space sampled with 2000 CFD and FEM computations, increases in blade torque have been obtained at each of the three tip-speed ratios (TSR) investigated, ranging from 6% at the nominal TSR to 14% at the lowest one, while stresses on the blade are kept almost unaltered.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2021
Barsi, Dario; Lengani, Davide; Simoni, Daniele; Venturino, Giulio; Bertini, Francesco; Rubechini, Filippo; Giovannini, Matteo
Analysis of the Loss Production Mechanism due to Cavity-Main Flow Interaction in a LPT Stage Proceeding
ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition June 7–11, 2021 Virtual, Online ASME, vol. GT2021-59932, 2021.
@proceedings{cavity2021,
title = {Analysis of the Loss Production Mechanism due to Cavity-Main Flow Interaction in a LPT Stage},
author = {Dario Barsi and Davide Lengani and Daniele Simoni and Giulio Venturino and Francesco Bertini and Filippo Rubechini and Matteo Giovannini},
url = {https://asmedigitalcollection.asme.org/GT/proceedings-abstract/GT2021/84935/V02DT39A012/1119835},
doi = {10.1115/GT2021-59932},
year = {2021},
date = {2021-09-16},
urldate = {2021-09-16},
volume = {GT2021-59932},
pages = {V02DT39A012; 12 pages},
publisher = {ASME},
organization = {ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition June 7–11, 2021 Virtual, Online},
abstract = {In the present work URANS simulations are presented to describe the unsteady interaction process between the flow ingested/ejected from a cavity system and the main flow evolving into a Low Pressure Turbine stage. Partic- ular care is posed on the analysis of the loss generation mechanisms acting outside the stator row and in the rear part of the axial gap separating the cavity flow ejection section and the leading edge plane of the downstream ro- tor row. The simulated geometry reproduces a typical en- gine cavity configuration, with upstream and downstream rotor rows reproduced by means of moving bars. Experi- mental results have been used to validate the simulations. This experimental data cannot explain and quantify alone the overall interaction process between the cavity flows and the main flow. The results of a simulation made by remov- ing the domain of the cavity have been employed in order to better highlight and quantify the effects due to main flow and cavity flows interaction on total pressure loss. A deep inspection of the loss amount along the axial direc- tion makes evident that losses generated in the vane row are basically increased prior to enter into the downstream rotor bars, due to cavity main flow interaction},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
2019
Rubechini, Filippo; Giovannini, Matteo; Arnone, Andrea; Simoni, Daniele; Bertini, Francesco
ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition June 17–21, 2019 Phoenix, Arizona, USA ASME, vol. Volume 2B: Turbomachinery, no. GT2019-91280, 2019, ISBN: 978-0-7918-5856-1.
@proceedings{Rubechini2019,
title = {Reducing Secondary Flow Losses in Low-Pressure Turbines With Blade Fences: Part I — Design in an Engine-Like Environment},
author = {Filippo Rubechini and Matteo Giovannini and Andrea Arnone and Daniele Simoni and Francesco Bertini},
url = {https://asmedigitalcollection.asme.org/GT/proceedings-abstract/GT2019/58561/V02BT40A020/1066491},
doi = {10.1115/GT2019-91280},
isbn = {978-0-7918-5856-1},
year = {2019},
date = {2019-11-05},
volume = {Volume 2B: Turbomachinery},
number = {GT2019-91280},
publisher = {ASME},
organization = {ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition June 17–21, 2019 Phoenix, Arizona, USA},
abstract = {This paper deals with the design of passive control devices for reducing the impact of secondary flows on the aerodynamics of low-pressure turbine (LPT) stages. A novel kind of device is introduced which consists of shelf-like fences to be added to the blade surface. Such a device is intended to hinder the development of secondary flows, thus reducing losses and flow turning deviation with respect to the straight blade.
The first part of this work is devoted to the design of the blade fences, whereas the second part addresses the experimental validation of the device. The blade fences are designed on a LPT stator vane, in an engine-like environment. As secondary flows generated by one blade row produce their major effects on the downstream one, and hence on the stage performance, the assessment is performed on a stator-rotor configuration. Steady calculations are considered for the design, then the optimal geometry is verified via unsteady calculations to include the effects of the actual interaction. The geometry and layout of the blade fences are effectively handled by means of a parametric approach, which enables the fast generation of several configurations. An optimization procedure, based on Artificial Neural Networks (ANNs) is exploited to drive the fences design. The analysis of the relative merit of each solution is carried out using a state-of-the-art CFD approach. Finally, a detailed comparison between the original blade and the one equipped with fences is presented, and the physical mechanisms responsible for the mitigation of secondary flow losses are discussed in detail.},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
The first part of this work is devoted to the design of the blade fences, whereas the second part addresses the experimental validation of the device. The blade fences are designed on a LPT stator vane, in an engine-like environment. As secondary flows generated by one blade row produce their major effects on the downstream one, and hence on the stage performance, the assessment is performed on a stator-rotor configuration. Steady calculations are considered for the design, then the optimal geometry is verified via unsteady calculations to include the effects of the actual interaction. The geometry and layout of the blade fences are effectively handled by means of a parametric approach, which enables the fast generation of several configurations. An optimization procedure, based on Artificial Neural Networks (ANNs) is exploited to drive the fences design. The analysis of the relative merit of each solution is carried out using a state-of-the-art CFD approach. Finally, a detailed comparison between the original blade and the one equipped with fences is presented, and the physical mechanisms responsible for the mitigation of secondary flow losses are discussed in detail.
Giovannini, Matteo; Rubechini, Filippo; Amato, Giorgio; Arnone, Andrea; Simoni, Daniele; Yepmo, Vianney; Satta, Francesca; Bertini, Francesco
ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition June 17–21, 2019 Phoenix, Arizona, USA ASME, vol. Volume 2B: Turbomachinery, no. GT2019-91284, 2019, ISBN: 978-0-7918-5856-1.
@proceedings{Giovannini2019,
title = {Reducing Secondary Flow Losses in Low-Pressure Turbines With Blade Fences: Part II — Experimental Validation on Linear Cascades},
author = {Matteo Giovannini and Filippo Rubechini and Giorgio Amato and Andrea Arnone and Daniele Simoni and Vianney Yepmo and Francesca Satta and Francesco Bertini},
url = {https://asmedigitalcollection.asme.org/GT/proceedings-abstract/GT2019/58561/V02BT40A021/1066499},
doi = {10.1115/GT2019-91284},
isbn = {978-0-7918-5856-1},
year = {2019},
date = {2019-11-05},
volume = {Volume 2B: Turbomachinery},
number = {GT2019-91284},
publisher = {ASME},
organization = {ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition June 17–21, 2019 Phoenix, Arizona, USA},
abstract = {This paper deals with the design of passive control devices for reducing the impact of secondary flows on the aerodynamics of low-pressure turbine (LPT) stages. A novel kind of device is introduced which consists of shelf-like fences to be added to the blade surface. Such a device is intended to contrast the development of secondary flows, thus reducing losses and flow turning deviation with respect to the straight blade.
In this second part, an experimental campaign on a linear cascade is presented which is aimed at proving the beneficial impact of the blade fences. Experiments were carried out on a low-speed test-rig, equipped with a large scale blade representative of the stators of the engine-like environment considered in part I. Measurements are mainly focused on the stator losses and on the flow field at the stator exit. The performance of the blade fences was evaluated by comparing the straight cascade and the fenced ones. The measurements highlighted the impact of the blade fences on the development of the secondary flows, affecting both the stator losses and the non-uniformity of the flow field over the exit plane, which, in the actual stage environment, impacts the operation of the downstream blade row. Moreover, the comparison between CFD and experiments proved the accuracy of the CFD setup, thus suggesting its reliability in predicting the stage performance in the engine-like configuration.},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
In this second part, an experimental campaign on a linear cascade is presented which is aimed at proving the beneficial impact of the blade fences. Experiments were carried out on a low-speed test-rig, equipped with a large scale blade representative of the stators of the engine-like environment considered in part I. Measurements are mainly focused on the stator losses and on the flow field at the stator exit. The performance of the blade fences was evaluated by comparing the straight cascade and the fenced ones. The measurements highlighted the impact of the blade fences on the development of the secondary flows, affecting both the stator losses and the non-uniformity of the flow field over the exit plane, which, in the actual stage environment, impacts the operation of the downstream blade row. Moreover, the comparison between CFD and experiments proved the accuracy of the CFD setup, thus suggesting its reliability in predicting the stage performance in the engine-like configuration.
Giovannini, Matteo; Rubechini, Filippo; Marconcini, Michele; Arnone, Andrea; Bertini, Francesco
Reducing Secondary Flow Losses in Low-Pressure Turbines: The Snaked Blade Journal Article
In: Int. J. Turbomachinery Propulsion and Power, vol. 4, no. 3, 2019, (This paper is an extended version of the paper published in Proceedings of the European Turbomachinery Conference, ETC13, Lausanne, Switzerland, 8–12 April 2019; Paper No. 338).
@article{1023,
title = {Reducing Secondary Flow Losses in Low-Pressure Turbines: The Snaked Blade},
author = {Matteo Giovannini and Filippo Rubechini and Michele Marconcini and Andrea Arnone and Francesco Bertini},
editor = {MDPI},
url = {https://www.mdpi.com/2504-186X/4/3/28/htm},
doi = {10.3390/ijtpp4030028},
year = {2019},
date = {2019-08-21},
journal = {Int. J. Turbomachinery Propulsion and Power},
volume = {4},
number = {3},
address = {Lausanne (CH), 8-12 April 2019},
abstract = {This paper presents an innovative design for reducing the impact of secondary flows on the aerodynamics of low-pressure turbine (LPT) stages. Starting from a state-of-the-art LPT stage, a local reshaping of the stator blade was introduced in the end-wall region in order to oppose the flow turning deviation. This resulted in an optimal stator shape, able to provide a more uniform exit flow angle. The detailed comparison between the baseline stator and the redesigned one allowed for pointing out that the rotor row performance increased thanks to the more uniform inlet flow, while the stator losses were not significantly affected. Moreover, it was possible to derive some design rules and to devise a general blade shape, named ‘snaked’, able to ensure such results. This generalization translated in an effective parametric description of the ‘snaked’ shape, in which few parameters are sufficient to describe the optimal shape modification starting from a conventional design. The “snaked” blade concept and its design have been patented by Avio Aero. The stator redesign was then applied to a whole LPT module in order to evaluate the potential benefit of the ‘snaked’ design on the overall turbine performance. Finally, the design was validated by means of an experimental campaign concerning the stator blade. The spanwise distributions of the flow angle and pressure loss coefficient at the stator exit proved the effectiveness of the redesign in providing a more uniform flow to the successive row, while preserving the original stator losses.},
note = {This paper is an extended version of the paper published in Proceedings of the European Turbomachinery Conference, ETC13, Lausanne, Switzerland, 8–12 April 2019; Paper No. 338},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Cozzi, Lorenzo; Rubechini, Filippo; Giovannini, Matteo; Marconcini, Michele; Arnone, Andrea; Schneider, Andrea; Astrua, Pio
Capturing Radial Mixing in Axial Compressors With Computational Fluid Dynamics Journal Article
In: ASME Journal of Turbomachinery, vol. 141, no. 3, pp. 9, 2019, ISBN: 0889-504X.
@article{1020,
title = {Capturing Radial Mixing in Axial Compressors With Computational Fluid Dynamics},
author = {Lorenzo Cozzi and Filippo Rubechini and Matteo Giovannini and Michele Marconcini and Andrea Arnone and Andrea Schneider and Pio Astrua},
url = {https://asmedigitalcollection.asme.org/turbomachinery/article/141/3/031012/475779/Capturing-Radial-Mixing-in-Axial-Compressors-With},
doi = {10.1115/1.4041738},
isbn = {0889-504X},
year = {2019},
date = {2019-01-21},
journal = {ASME Journal of Turbomachinery},
volume = {141},
number = {3},
pages = {9},
abstract = {The current industrial standard for numerical simulations of axial compressors is the steady Reynolds-averaged Navier–Stokes (RANS) approach. Besides the well-known limitations of mixing planes, namely their inherent inability to capture the potential interaction and the wakes from the upstream blades, there is another flow feature which is lost, and which is a major accountable for the radial mixing: the transport of streamwise vorticity. Streamwise vorticity is generated for various reasons, mainly associated with secondary and tip-clearance flows. A strong link exists between the strain field associated with the vortices and the mixing augmentation: the strain field increases both the area available for mixing and the local gradients in fluid properties, which provide the driving potential for the mixing. In the rear compressor stages, due to high clearances and low aspect ratios, only accounting for the development of secondary and clearance flow structures, it is possible to properly predict the spanwise mixing. In this work, the results of steady and unsteady simulations on a heavy-duty axial compressor are compared with experimental data. Adopting an unsteady framework, the enhanced mixing in the rear stages is properly captured, in remarkable agreement with experimental distributions. On the contrary, steady analyses strongly underestimate the radial transport. It is inferred that the streamwise vorticity associated with clearance flows is a major driver of radial mixing, and restraining it by pitch-averaging the flow at mixing planes is the reason why the steady approach cannot predict the radial transport in the rear part of the compressor.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2018
Riccietti, Elisa; Bellucci, Juri; Checcucci, Matteo; Marconcini, Michele; Arnone, Andrea
Support Vector Machine Classification Applied to the Parametric Design of Centrifugal Pumps Journal Article
In: Engineering Optimization, vol. 50, pp. 1304-1324, 2018, ISSN: 1029-0273.
@article{986,
title = {Support Vector Machine Classification Applied to the Parametric Design of Centrifugal Pumps},
author = {Elisa Riccietti and Juri Bellucci and Matteo Checcucci and Michele Marconcini and Andrea Arnone},
url = {http://www.tandfonline.com/doi/full/10.1080/0305215X.2017.1391801},
doi = {dx.doi.org/10.1080/0305215X.2017.1391801},
issn = {1029-0273},
year = {2018},
date = {2018-11-01},
journal = {Engineering Optimization},
volume = {50},
pages = {1304-1324},
abstract = {In this article the parametric design of centrifugal pumps is addressed. To deal with thisproblem, an approach based on coupling expensive Computational Fluid Dynamics (CFD) computations with Artificial Neural Networks (ANN) as a regression meta-model had been proposed in Checcucci et al. (2015), "A Novel Approach to Parametric Design of Centrifugal Pumps for a Wide Range of Specific Speeds."; ISAIF 12 paper n.121. Here, the previously proposed approach is improved by including also the use of Support Vector Machines (SVM) as a classification tool. The classification process is aimed at identifying parameters combinations corresponding to manufacturable machines among the much larger number of unfeasible ones. A binary classification problem on an unbalanced dataset has to be faced. Numerical tests show that the addition of this classification tool helps to considerably reduce the number of CFD computations required for the design, providing large savings in computational time.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Giovannini, Matteo; Rubechini, Filippo; Marconcini, Michele; Simoni, Daniele; Yepmo, Vianney; Bertini, Francesco
In: ASME Journal of Turbomachinery, vol. 140, no. 11, pp. 111002 (12 pages), 2018, ISSN: 0889-504X.
@article{1019,
title = {Secondary Flows in Low-Pressure Turbines Cascades: Numerical and Experimental Investigation of the Impact of the Inner Part of the Boundary Layer},
author = {Matteo Giovannini and Filippo Rubechini and Michele Marconcini and Daniele Simoni and Vianney Yepmo and Francesco Bertini},
url = {http://turbomachinery.asmedigitalcollection.asme.org/article.aspx?articleid=2702055&resultClick=3},
doi = {10.1115/1.4041378},
issn = {0889-504X},
year = {2018},
date = {2018-10-01},
journal = {ASME Journal of Turbomachinery},
volume = {140},
number = {11},
pages = {111002 (12 pages)},
abstract = {Due to the low level of profile losses reached in low-pressure turbines (LPT) for turbofan applications, a renewed interest is devoted to other sources of loss, e.g., secondary losses. At the same time, the adoption of high-lift profiles has reinforced the importance of these losses. A great attention, therefore, is dedicated to reliable prediction methods and to the understanding of the mechanisms that drive the secondary flows. In this context, a numerical and experimental campaign on a state-of-the-art LPT cascade was carried out focusing on the impact of different inlet boundary layer (BL) profiles. First of all, detailed Reynolds Averaged Navier-Stokes (RANS) analyzes were carried out in order to establish dependable guidelines for the computational setup. Such analyzes also underlined the importance of the shape of the inlet BL very close to the endwall, suggesting tight requirements for the characterization of the experimental environment. The impact of the inlet BL on the secondary flow was experimentally investigated by varying the inlet profile very close to the endwall as well as on the external part of the BL. The effects on the cascade performance were evaluated by measuring the span-wise distributions of flow angle and total pressure losses. For all the inlet conditions, comparisons between Computational Fluid Dynamics (CFD) and experimental results are discussed. Besides providing guidelines for a proper numerical and experimental setup, the present paper underlines the importance of a detailed characterization of the inlet BL for an accurate assessment of the secondary flows.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Cozzi, Lorenzo; Rubechini, Filippo; Giovannini, Matteo; Marconcini, Michele; Arnone, Andrea; Schneider, Andrea; Astrua, Pio
Capturing Radial Mixing in Axial Compressors with CFD Conference
ASME Turbo Expo 2018: Turbine Technical Conference and Exposition, vol. Volume 2C: Turbomachinery, ASME ASME, Oslo, Norway, 2018, ISBN: 978-0-7918-5101-2, (paper GT2018-75942).
@conference{1001,
title = {Capturing Radial Mixing in Axial Compressors with CFD},
author = {Lorenzo Cozzi and Filippo Rubechini and Matteo Giovannini and Michele Marconcini and Andrea Arnone and Andrea Schneider and Pio Astrua},
url = {http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=2700721&resultClick=3},
doi = {10.1115/GT2018-75942},
isbn = {978-0-7918-5101-2},
year = {2018},
date = {2018-01-01},
booktitle = {ASME Turbo Expo 2018: Turbine Technical Conference and Exposition},
volume = {Volume 2C: Turbomachinery},
pages = {pp. V02CT42A025; 11 pages},
publisher = {ASME},
address = {Oslo, Norway},
organization = {ASME},
abstract = {Due to the generally high stage and blade count, the current standard industrially adopted to perform numerical simulations on multistage axial compressors is the steady-state analysis based on the Reynolds-averaged Navier-Stokes approach (RANS), where the coupling between adjacent rows is handled by means of mixing planes. In addition to the well-known limitations of a steady-state picture of the flow, namely its inherent inability to capture the potential interaction and the wakes from the upstream blades, there is another flow feature which is lost through a mixing-plane, and which is believed to be a major accountable for the radial mixing: the transport of stream-wise vorticity. Streamwise vorticity arises throughout a compressor for various reasons, mainly associated with secondary and tip-clearance flows. A strong link does exist between the strain field associated with the transported vortices and the mixing augmentation: the strain field increases both the area available for mixing and the local gradients in fluid properties, which provide the driving potential for mixing itself. Especially for the rear stages of a multistage axial compressor, due to high clearances and low aspect ratios, only accounting for the development along the meridional path of secondary and clearance flow structures (e.g. running an unsteady computation) it is possible to properly predict the spanwise mixing. Within this paper, the results of steady and unsteady simulations performed on a heavy-duty multistage axial compressor of Ansaldo Energia fleet are compared with experimental data, showing the importance of modelling the unsteady interactions in capturing the radial mixing. This compressor was selected because of the enhanced radial mixing effect experimentally measured in its high-pressure section.},
note = {paper GT2018-75942},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Giovannini, Matteo; Rubechini, Filippo; Marconcini, Michele; Simoni, Daniele; Yepmo, Vianney; Bertini, Francesco
ASME Turbo Expo 2018: Turbine Technical Conference and Exposition, vol. Volume 2B: Turbomachinery, ASME ASME, Oslo, Norway, 2018, ISBN: 978-079185100-5, (paper GT2018-76737).
@conference{1000,
title = {Secondary Flows in LPT Cascades: Numerical and Experimental Investigation of the Impact of the Inner Part of the Boundary Layer},
author = {Matteo Giovannini and Filippo Rubechini and Michele Marconcini and Daniele Simoni and Vianney Yepmo and Francesco Bertini},
url = {http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=2700647},
doi = {10.1115/GT2018-76737},
isbn = {978-079185100-5},
year = {2018},
date = {2018-01-01},
booktitle = {ASME Turbo Expo 2018: Turbine Technical Conference and Exposition},
volume = {Volume 2B: Turbomachinery},
pages = {pp. V02BT41A027; 13 pages},
publisher = {ASME},
address = {Oslo, Norway},
organization = {ASME},
abstract = {Due to the low level of profile losses already reached in the design of modern low-pressure turbines for turbofan applications, a renewed interest is devoted to the other sources of loss, and namely to the secondary losses. At the same time, the importance of secondary losses has been reinforced by the current design trend towards high-lift profiles. A great attention, therefore, is dedicated to reliable and effective prediction methods as well as on the correct understanding of the mechanisms that drive the secondary flows. In this context, a systematic numerical and experimental campaign was carried out focusing on the impact of different inlet boundary layer (BL) profiles and considering a state-of-the-art low-pressure turbine cascade. Starting from a computational environment representative of a design standard, detailed RANS analyses were carried out in order to establish dependable guidelines for the computational setup. As a major result, such analyses also underlined the importance of the shape of the inlet BL very close to the endwall, hence suggesting tight requirements for the characterization of the experimental environment. The impact of the inlet BL profile on the secondary flow development was experimentally investigated by varying the profile shape very close to the endwall as well as on the external part with respect to a reference condition. The effects on the cascade performance were evaluated focusing on the intensity of the over- under-turning as well as on the associated losses (intensity and penetration) by measuring the span-wise distributions of flow angle and total pressure losses at the cascade exit plane. For all the inlet conditions, comparisons between CFD and experimental results are discussed. Besides providing guidelines for a proper numerical and experimental setup, the present paper underlines the importance of a detailed characterization of the inlet BL for an accurate assessment of the secondary flows. From a broader perspective, when aiming at reproducing (numerically or experimentally) a real engine environment, this suggests that an in-depth matching of the inlet profiles is crucial for reliable estimates of the secondary losses.},
note = {paper GT2018-76737},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Peruzzi, Lorenzo; Bellucci, Juri; Pinelli, Lorenzo; Marconcini, Michele; Gatta, G; Colatoni, S; Abhimanyu, S; Natale, G
Flutter-free design of aeroderivative gas turbine nozzles with simplified aero-mechanical models Conference
15th International Symposium on Unsteady Aerodynamics, Aeroacoustics and Aeroelasticity of Turbomachines (ISUAAAT), September 23-27, Oxford, UK, 2018, (paper ISUAAAT15-037).
@conference{1016,
title = {Flutter-free design of aeroderivative gas turbine nozzles with simplified aero-mechanical models},
author = {Lorenzo Peruzzi and Juri Bellucci and Lorenzo Pinelli and Michele Marconcini and G Gatta and S Colatoni and S Abhimanyu and G Natale},
year = {2018},
date = {2018-01-01},
booktitle = {15th International Symposium on Unsteady Aerodynamics, Aeroacoustics and Aeroelasticity of Turbomachines (ISUAAAT)},
address = {September 23-27, Oxford, UK},
abstract = {This work presents a simplified procedure to design a flutter free
airfoil geometry for aeroderivative gas turbine stator blade rows. The
common workflow for a fully 3D flutter numerical assessment with an
uncoupled method firstly involves a FE modal analysis to obtain the
airfoil mode shapes which will be used for unsteady aeroelastic
computations with moving airfoil. Nozzle geometries are usually very
complex: airfoils in a packet configuration and different mechanical
features needed to attach the packet itself to the turbine casing make
the structural meshing a not trivial task.
The aim of this paper is to demonstrate how, in the early
aero-mechanical design phases simplified models including only the
airfoil geometry and the endwalls chunks can be efficiently used to
design flutter-free components. First of all, detailed comparisons
between modal results from full and simplified mechanical models have
been performed. Then, flutter computations have been carried out using
modal results both from the full mechanical model (the sector or packet
model) and two different simplified models (single airfoil models).
Finally, flutter results in terms of logarithmic decrement curves will
be presented, showing the capability of this approach to guarantee
flutter free geometries even from the early design stages. This aspect
is essential to avoid bladerow redesign due to flutter issues which may
occur during the final design of the airfoil.},
note = {paper ISUAAAT15-037},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
airfoil geometry for aeroderivative gas turbine stator blade rows. The
common workflow for a fully 3D flutter numerical assessment with an
uncoupled method firstly involves a FE modal analysis to obtain the
airfoil mode shapes which will be used for unsteady aeroelastic
computations with moving airfoil. Nozzle geometries are usually very
complex: airfoils in a packet configuration and different mechanical
features needed to attach the packet itself to the turbine casing make
the structural meshing a not trivial task.
The aim of this paper is to demonstrate how, in the early
aero-mechanical design phases simplified models including only the
airfoil geometry and the endwalls chunks can be efficiently used to
design flutter-free components. First of all, detailed comparisons
between modal results from full and simplified mechanical models have
been performed. Then, flutter computations have been carried out using
modal results both from the full mechanical model (the sector or packet
model) and two different simplified models (single airfoil models).
Finally, flutter results in terms of logarithmic decrement curves will
be presented, showing the capability of this approach to guarantee
flutter free geometries even from the early design stages. This aspect
is essential to avoid bladerow redesign due to flutter issues which may
occur during the final design of the airfoil.
Amato, Giorgio; Giovannini, Matteo; Marconcini, Michele; Arnone, Andrea
Unsteady Methods Applied to a Transonic Aeronautical Gas Turbine Stage Journal Article
In: Energy Procedia, vol. 148, pp. 74-81, 2018, ISSN: 1876-6102, (ATI 2018 - 73rd Conference of the Italian Thermal Machines Engineering Association).
@article{1011,
title = {Unsteady Methods Applied to a Transonic Aeronautical Gas Turbine Stage},
author = {Giorgio Amato and Matteo Giovannini and Michele Marconcini and Andrea Arnone},
url = {https://www.sciencedirect.com/science/article/pii/S1876610218303229},
doi = {10.1016/j.egypro.2018.08.032},
issn = {1876-6102},
year = {2018},
date = {2018-01-01},
journal = {Energy Procedia},
volume = {148},
pages = {74-81},
address = {Pisa, Italy, 12-14 September},
abstract = {The importance of considering the unsteady effects in aeronautical engine design has brought to the implementation of simplified unsteady CFD models to respect the temporal restrictions of design cycles. A comparison among steady, Non-Linear Harmonic (NLH) and Full-Annulus (FA) methods has been carried out analyzing the transonic turbine stage CT3, experimentally studied at von Karman Institute for Fluid Dynamics. The understanding of the unsteady phenomena is fundamental to increase the engine efficiency and is precluded in steady calculations. As the computational cost of NLH calculations is of the same order of magnitude of steady ones, it represents a valid and competitive option in a turbine design process.},
note = {ATI 2018 - 73rd Conference of the Italian Thermal Machines Engineering Association},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2017
Becciani, Michele; Bianchini, Alessandro; Checcucci, Matteo; Ferrari, Lorenzo; Luca, Michele De; Marmorini, Luca; Arnone, Andrea; Ferrara, Giovanni
13th International Conference on Engines & Vehicles, September 10-14, 2017, Capri, Italy, 2017, (SAE Technical Paper 2017-24-0020).
@conference{999,
title = {A Pre-Design Model to Estimate the Effect of Variable Inlet Guide Vanes on the Performance Map of a Centrifugal Compressor for Automotive Applications},
author = {Michele Becciani and Alessandro Bianchini and Matteo Checcucci and Lorenzo Ferrari and Michele De Luca and Luca Marmorini and Andrea Arnone and Giovanni Ferrara},
url = {http://papers.sae.org/2017-24-0020/},
doi = {10.4271/2017-24-0020},
year = {2017},
date = {2017-09-01},
booktitle = {13th International Conference on Engines & Vehicles},
address = {September 10-14, 2017, Capri, Italy},
abstract = {The onset of aerodynamic instabilities in proximity of the left margin of the operating curve represents one of the main limitations for centrifugal compressors in turbocharging applications. An anticipated stall/surge onset is indeed particularly detrimental at those high boost pressures that are typical of engine downsizing applications using a turbocharger. Several stabilization techniques have been investigated so far to increase the rangeability of the compressor without excessively reducing the efficiency. One of the most exploited solutions is represented by the use of upstream axial variable inlet guide vanes (VIGV) to impart a pre-whirl angle to the inlet flow. In the pre-design phase of a new stage or when selecting, for example, an existing unit from an industrial catalogue, it is however not easy to get a prompt estimation of the attended modifications induced by the VIGV on the performance map of the compressor.A simplified model to this end is presented in the study. Figuring out a typical industrial pre-design phase, the model assumes the availability of the original performance data of the compressor without pre-whirl and only very few geometrical parameters. Based on fluid dynamic considerations and some additional models and correlations, a procedure is defined to correct the attended stage pressure ratio and efficiency as a function of the pre-whirl angle imposed by the VIGV. The model has been successfully validated using an experimental literature case study and is thought to represent a new useful preliminary tool for turbocharger designers.},
note = {SAE Technical Paper 2017-24-0020},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Marconcini, Michele; Bianchini, Alessandro; Checcucci, Matteo; Ferrara, Giovanni; Arnone, Andrea; Ferrari, Lorenzo; Biliotti, Davide; Rubino, Dante Tommaso
In: ASME Journal of Turbomachinery, vol. 139, pp. 021001, 2017, ISSN: 0889-504X.
@article{987,
title = {A Three-Dimensional Time-Accurate Computational Fluid Dynamics Simulation of the Flow Field Inside a Vaneless Diffuser During Rotating Stall Conditions},
author = {Michele Marconcini and Alessandro Bianchini and Matteo Checcucci and Giovanni Ferrara and Andrea Arnone and Lorenzo Ferrari and Davide Biliotti and Dante Tommaso Rubino},
url = {http://turbomachinery.asmedigitalcollection.asme.org/article.aspx?articleid=2551877},
doi = {dx.doi.org/10.1115/1.4034633},
issn = {0889-504X},
year = {2017},
date = {2017-09-01},
journal = {ASME Journal of Turbomachinery},
volume = {139},
pages = {021001},
abstract = {An accurate characterization of rotating stall in terms of inception modality, flow structures, and stabilizing force is one of the key goals for high-pressure centrifugal compressors. The unbalanced pressure field that is generated within the diffuser can be in fact connected to a non-negligible aerodynamic force and then to the onset of detrimental sub-synchronous vibrations which can prevent the machine from operating beyond this limit. An inner comprehension on how the induced flow pattern in these conditions affects the performance of the impeller and its mechanical stability can therefore lead to the development of a more effective regulation system able to mitigate the effects of the phenomenon and extend the left-side margin of the operating curve. In the present study, a 3D-unsteady CFD approach was applied to the simulation of a radial stage model including the impeller, the vaneless diffuser and the return channel. Simulations were carried out with the TRAF code of the University of Florence. The tested rotor was an industrial impeller operating at high peripheral Mach number, for which unique experimental pressure measurements, including the spatial reconstruction of the pressure field at the diffuser inlet, were available. The comparison between experiments and simulations showed a good matching and corroborated the CFD capabilities in correctly describing also some of the complex unsteady phenomena taking place in proximity of the left margin of the operating curve.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Marconcini, Michele; Bianchini, Alessandro; Checcucci, Matteo; Biliotti, Davide; Giachi, Marco; Rubino, Dante Tommaso; Arnone, Andrea; Carnevale, Ennio Antonio; Ferrari, Lorenzo; Ferrara, Giovanni
Determinazione della forza indotta dallo stallo rotante nei compressori centrifughi con diffusore liscio Journal Article
In: La Termotecnica, vol. 3, pp. 50-54, 2017, ISSN: 0040-3725.
@article{996,
title = {Determinazione della forza indotta dallo stallo rotante nei compressori centrifughi con diffusore liscio},
author = {Michele Marconcini and Alessandro Bianchini and Matteo Checcucci and Davide Biliotti and Marco Giachi and Dante Tommaso Rubino and Andrea Arnone and Ennio Antonio Carnevale and Lorenzo Ferrari and Giovanni Ferrara},
url = {http://www.verticale.net/determinazione-della-forza-indotta-dallo-stallo-11019},
issn = {0040-3725},
year = {2017},
date = {2017-05-01},
journal = {La Termotecnica},
volume = {3},
pages = {50-54},
abstract = {Una corretta stima della forza destabilizzante indotta dallo stallo rotante è un elemento chiave per i produttori di macchine industriali in vista in vista di una estensione del margine sinistro dei compressori centrifughi. In questo studio, i risultati di alcune simulazioni 3D instazionarie sono stati usati per stimare la forza di stallo su uno stadio e paragonare tale stima a quella ottenuta con un approccio che ricalca quello sperimentale generalmente usato al banco prova basato su sensori dinamici di pressione. L'analisi ha mostrato che: a) il metodo sperimentale, basato su media d'assieme, è in grado di fornire risultati accurati, nonostante alcune ipotesi semplificative; b) il contributo della quantità di moto risulta trascurabile per l'intensità della forza.
ESTIMATION OF THE AERODYNAMIC FORCE INDUCED BY VANELESS DIFFUSER ROTATING STALL IN CENTRIFUGAL COMPRESSOR STAGES
A correct estimation of the destabilizing force due rotating stall is a key element for industrial manufacturers in view of an extension of the minimum flow limit of centrifugal compressor stages. In this study, the results of a 3D-unsteady CFD simulation were used to estimate the stall force on a stage and to compare it with the approximation obtained with a method similar to that usually employed at the test rig by means of dynamic pressure sensors. Results showed that: a) the experimental approach, using an ensemble average for transposing data from time to space domain, provides robust results; b) the momentum gives a negligible contribution to the intensity of the stall force.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
ESTIMATION OF THE AERODYNAMIC FORCE INDUCED BY VANELESS DIFFUSER ROTATING STALL IN CENTRIFUGAL COMPRESSOR STAGES
A correct estimation of the destabilizing force due rotating stall is a key element for industrial manufacturers in view of an extension of the minimum flow limit of centrifugal compressor stages. In this study, the results of a 3D-unsteady CFD simulation were used to estimate the stall force on a stage and to compare it with the approximation obtained with a method similar to that usually employed at the test rig by means of dynamic pressure sensors. Results showed that: a) the experimental approach, using an ensemble average for transposing data from time to space domain, provides robust results; b) the momentum gives a negligible contribution to the intensity of the stall force.
Cozzi, Lorenzo; Rubechini, Filippo; Marconcini, Michele; Arnone, Andrea; Astrua, Pio; Schneider, Andrea; Silingardi, Andrea
Facing the Challenges in CFD Modelling of Multistage Axial Compressors Conference
ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition, vol. 2B: Turbomachinery, ASME ASME, Charlotte, NC, USA, 2017, ISBN: 978-0-7918-5079-4, (ASME paper GT2017-63240).
@conference{990,
title = {Facing the Challenges in CFD Modelling of Multistage Axial Compressors},
author = {Lorenzo Cozzi and Filippo Rubechini and Michele Marconcini and Andrea Arnone and Pio Astrua and Andrea Schneider and Andrea Silingardi},
url = {http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleID=2649617},
doi = {10.1115/GT2017-63240},
isbn = {978-0-7918-5079-4},
year = {2017},
date = {2017-01-01},
booktitle = {ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition},
volume = {2B: Turbomachinery},
pages = {pp. V02BT41A007; 11 pages},
publisher = {ASME},
address = {Charlotte, NC, USA},
organization = {ASME},
abstract = {Multistage axial compressors have always been a great challenge for designers since the flow within these kind of machines, subjected to severe diffusion, is usually characterized by complex and widely developed 3D structures, especially next to the endwalls. The development of reliable numerical tools capable of providing an accurate prediction of the overall machine performance is one of the main research focus areas in the multistage axial compressor field. This paper is intended to present the strategy used to run numerical simulations on compressors achieved by the collaboration between the University of Florence and Ansaldo Energia. All peculiar aspects of the numerical setup are introduced, such as rotor/stator tip clearance modelling, simplified shroud leakage model, gas and turbulence models. Special attention is payed to the mixing planes adopted for steady-state computations because this is a crucial aspect of modern heavy-duty transonic multi stage axial compressors. In fact, these machines are characterized by small inter-row axial gaps and transonic flow in front stages, which both may affect non-reflectiveness and fluxes conservation across mixing planes. Moreover, the high stage count may lead to conservation issues of the main flow properties form inlet to outlet boundaries. Finally, the likely occurrence of part span flow reversal in the endwall regions affects the robustness of non-reflecting mixing plane models. The numerical setup has been validated on an existing machine produced and experimentally tested by Ansaldo Energia. In order to evaluate the impact on performance prediction of the mixing planes introduced in the steady-state computation, unsteady simulations of the whole compressor have been performed at different operating conditions. These calculations have been carried out both at the compressor design point and close to the surge-line to evaluate the effect of rotor/stator interaction along the compressor working line.},
note = {ASME paper GT2017-63240},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Bellucci, Juri; Rubechini, Filippo; Arnone, Andrea; Arcangeli, Lorenzo; Maceli, Nicola; Paradiso, Berardo; Gatti, Giacomo
Numerical and experimental investigation of axial gap variation in high pressure steam turbine stages Journal Article
In: Journal of Engineering for Gas Turbines and Power, vol. 139, pp. 052603 (9 pages), 2017, ISSN: 0742-4795.
@article{988,
title = {Numerical and experimental investigation of axial gap variation in high pressure steam turbine stages},
author = {Juri Bellucci and Filippo Rubechini and Andrea Arnone and Lorenzo Arcangeli and Nicola Maceli and Berardo Paradiso and Giacomo Gatti},
url = {http://gasturbinespower.asmedigitalcollection.asme.org/article.aspx?articleid=2580913},
doi = {dx.doi.org/10.1115/1.4035158},
issn = {0742-4795},
year = {2017},
date = {2017-01-01},
journal = {Journal of Engineering for Gas Turbines and Power},
volume = {139},
pages = {052603 (9 pages)},
abstract = {This work aims at investigating the impact of axial gap variation on aerodynamic performance of a HP steam turbine stage. Numerical and experimental campaigns were conducted on a 1.5-stage of a reaction steam turbine. This low speed rig was operated in different operating conditions. Two different configurations were studied, in which blades axial gap was varied in a range from 40% to 95%. Numerical analyses were carried out by means of three-dimensional, viscous, unsteady simulations, adopting measured inlet/outlet boundary conditions. Two set of measurements were performed. Steady measurements, from one hand, for global performance estimation of the whole turbine. Steady and unsteady measurements, on the other hand, were performed downstream of rotor row, in order to characterize the flow structures in this region. The fidelity of computational setup was proven by comparing numerical results to measurements. Main performance curves and span-wise distributions shown a good agreement in terms of both shape of curves/distributions and absolute values. Moreover, the comparison of two dimensional maps downstream of rotor row shown similar structures of the flow field. Finally, a comprehensive study of the axial gap effect on stage aerodynamic performance was carried out for four blade spacings, and five aspect ratios. The results pointed out how unsteady interaction between blade rows affects stage operation, in terms of pressure and flow angle distributions, as well as of secondary flows development. The combined effect of these aspects in determining the stage efficiency is investigated and discussed in detail.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Paradiso, Berardo; Gatti, Giacomo; Bellucci, Juri; Mora, Alessandro; Dossena, Vincenzo; Arcangeli, Lorenzo; Maceli, Nicola
An Experimental and Numerical Investigation of the Performance Impact of a Heavily Off-Design Inlet Swirl Angle in a Steam Turbine Stage Conference
ASME Turbo Expo 2017: Turbine Technical Conference and Exposition, Charlotte, NC, USA, 2017, (ASME paper GT2017-64561).
@conference{997,
title = {An Experimental and Numerical Investigation of the Performance Impact of a Heavily Off-Design Inlet Swirl Angle in a Steam Turbine Stage},
author = {Berardo Paradiso and Giacomo Gatti and Juri Bellucci and Alessandro Mora and Vincenzo Dossena and Lorenzo Arcangeli and Nicola Maceli},
year = {2017},
date = {2017-01-01},
booktitle = {ASME Turbo Expo 2017: Turbine Technical Conference and Exposition},
address = {Charlotte, NC, USA},
abstract = {The aim of this work is to provide an insight into the performance reduction of a 1.5 axial steam turbine stage working under extreme incidence conditions at the inlet. In particular, the main object of the study is the propagation of the loss cores across the blade rows, so as to assess how such operating conditions affect the full machine. Experimental data have been used to validate an unsteady three-dimensional numerical simulation, which provided the tools to investigate the flowfield in detail. To do so, the 1.5 turbine stage installed in the Low Speed Test Rig at Politecnico di Milano has been tested with design and off-design inlet conditions by modifying the IGV orientation. The inter-stage flowfield was investigated by traversing pressure probes in three different axial planes, downstream of each blade row. The numerical simulation has been carried out at University of Florence. The experimental data from probes traversing was used as boundary conditions so as to match as closely as possible the actual operative parameters of the stage. Data from flange-to-flange measurements on the test rig were also used to compare the stage efficiency. After the successful validation of the numerical results, the loss cores propagation study itself was carried out. Using CFD results, the unsteady nature of the separation occurring on the first stator in off-design condition is investigated. Subsequently, a detailed analysis of the propagation of the loss cores is presented, including loss coefficients calculation and entropy trends along the machines axial coordinate. The main outcome is that at the machine exit the loss structures appear to be mainly mixed out and, therefore, subsequent stages would operate under conditions not far from the nominal ones.},
note = {ASME paper GT2017-64561},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
2016
Gatti, Giacomo; Gaetani, Paolo; Paradiso, Berardo; Dossena, Vincenzo; Arcangeli, Lorenzo; Maceli, Nicola; Bellucci, Juri
An Experimental Study of the Aerodynamic Forcing Function in a 1.5 Steam Turbine Stage Journal Article
In: Journal of Engineering for Gas Turbines and Power, vol. 139, pp. 052503, 2016, ISSN: 0742-4795.
@article{989,
title = {An Experimental Study of the Aerodynamic Forcing Function in a 1.5 Steam Turbine Stage},
author = {Giacomo Gatti and Paolo Gaetani and Berardo Paradiso and Vincenzo Dossena and Lorenzo Arcangeli and Nicola Maceli and Juri Bellucci},
url = {http://gasturbinespower.asmedigitalcollection.asme.org/article.aspx?articleid=2569877},
doi = {dx.doi.org/10.1115/1.4034967},
issn = {0742-4795},
year = {2016},
date = {2016-12-01},
journal = {Journal of Engineering for Gas Turbines and Power},
volume = {139},
pages = {052503},
abstract = {The usual ways to measure the aerodynamic forcing function are complex and expensive. The aim of this work is to evaluate the forces acting on the blades using a relatively simpler experimental methodology based on a time-resolved pressure measurement at the rotor discharge. Upstream of the rotor, a steady three holes probe has been used. The post processing procedures are described in detail, including the application of a phase-locked average and of an extension algorithm with phase-lag. The algorithm for the computation of the force components is presented, along with the underlying assumptions. In order to interpret the results, a preliminary description of the flow field, both upstream and downstream of the rotor, is provided. This gives an insight of the most relevant features that affect the computation of the forces. Finally, the analysis of the results is presented. These are first described and then compared with overall section-average results (torque-sensor), and with the results from 3D unsteady simulations (integral of pressure over the blade surface) in order to assess the accuracy of the method. Both the experimental and the numerical results are also compared for two different operating conditions with increasing stage load.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Pacciani, Roberto; Rubechini, Filippo; Marconcini, Michele; Arnone, Andrea; Cecchi, Stefano; Daccà, Federico
A CFD-Based Throughflow Method With An Adaptive Formulation For The S2 Streamsurface Journal Article
In: Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, vol. 230, pp. 16-28, 2016, ISSN: 0957-6509.
@article{967,
title = {A CFD-Based Throughflow Method With An Adaptive Formulation For The S2 Streamsurface},
author = {Roberto Pacciani and Filippo Rubechini and Michele Marconcini and Andrea Arnone and Stefano Cecchi and Federico Daccà},
url = {http://pia.sagepub.com/content/230/1/16},
doi = {dx.doi.org/10.1177/0957650915607091},
issn = {0957-6509},
year = {2016},
date = {2016-09-01},
journal = {Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy},
volume = {230},
pages = {16-28},
abstract = {The paper describes the development and validation of a novel CFD-based throughflow model. It is based on the axisymmetric Euler equations with tangential blockage and body forces and inherits its numerical scheme from state-of-the-art CFD solver (TRAF code), including real-gas capabilities. A crucial aspect of the numerical procedure is represented by an adaptive approach for the meridional flow surface, which employs a new time-dependent equation to accommodate incidence and deviation effects, and which allows the explicit calculation of the blade body force. A realistic distribution of entropy along the streamlines is proposed in order to compute dissipative forces on the base of a distributed loss model. The throughflow code is applied to the investigation of a four stage low-pressure steam turbine at design conditions. The performance of the method are evaluated by comparing predicted operating characteristics and spanwise distributions of flow quantities with the results of CFD, steady, viscous calculations and experimental data.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Giovannini, Matteo; Marconcini, Michele; Rubechini, Filippo; Arnone, Andrea; Bertini, Francesco
Scaling Three-Dimensional Low-Pressure Turbine Blades for Low-Speed Testing Journal Article
In: ASME Journal of Turbomachinery, vol. 138, pp. 111001-1-9, 2016, ISSN: 0889-504X.
@article{984,
title = {Scaling Three-Dimensional Low-Pressure Turbine Blades for Low-Speed Testing},
author = {Matteo Giovannini and Michele Marconcini and Filippo Rubechini and Andrea Arnone and Francesco Bertini},
url = {http://turbomachinery.asmedigitalcollection.asme.org/article.aspx?articleID=2512185},
doi = {dx.doi.org/10.1115/1.4033259},
issn = {0889-504X},
year = {2016},
date = {2016-05-01},
journal = {ASME Journal of Turbomachinery},
volume = {138},
pages = {111001-1-9},
abstract = {The present activity was carried out in the framework of the Clean Sky European research project ITURB (Optimal High-Lift Turbine Blade Aero-Mechanical Design), aimed at designing and validating a turbine blade for a geared open rotor engine. A cold-flow, large-scale, low-speed (LS) rig was built in order to investigate and validate new design criteria, providing reliable and detailed results while containing costs. This paper presents the design of a LS stage, and describes a general procedure that allows to scale 3D blades for low-speed testing. The design of the stator row was aimed at matching the test-rig inlet conditions and at providing the proper inlet flow field to the blade row. The rotor row was redesigned in order to match the performance of the high-speed one, compensating for both the compressibility effects and different turbine flow paths. The proposed scaling procedure is based on the matching of the 3D blade loading distribution between the real engine environment and the LS facility one, which leads to a comparable behavior of the boundary layer and hence to comparable profile losses. To this end, the datum blade is parameterized, and a neural-network based methodology is exploited to guide an optimization process based on 3D RANS computations. The LS stage performance were investigated over a range of Reynolds numbers characteristic of modern low-pressure turbines by using a multi-equation, transition-sensitive, turbulence model.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Giovannini, Matteo; Rubechini, Filippo; Marconcini, Michele; Arnone, Andrea; Bertini, Francesco
Analysis of a LPT Rotor Blade For a Geared Engine. Part I: Aero-Mechanical Design and Validation Conference
ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition, vol. 2B: Turbomachinery, Seoul, South Korea, June 13–17, 2016, 2016, ISBN: 978-0-7918-4970-5, (GT2016-57746).
@conference{980,
title = {Analysis of a LPT Rotor Blade For a Geared Engine. Part I: Aero-Mechanical Design and Validation},
author = {Matteo Giovannini and Filippo Rubechini and Michele Marconcini and Andrea Arnone and Francesco Bertini},
url = {http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleID=2554742},
doi = {10.1115/GT2016-57746},
isbn = {978-0-7918-4970-5},
year = {2016},
date = {2016-01-01},
booktitle = {ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition},
volume = {2B: Turbomachinery},
pages = {V02BT38A053; 12 pages},
address = {Seoul, South Korea, June 13–17, 2016},
abstract = {The rotational speed of low pressure turbines (LPT) for geared turbofan applications is significantly increased looking for potential benefit in performance, weight and overall dimensions. As a drawback, the high speed LPT are characterized by critical mechanical constraints due to the large centrifugal stresses in conjunction with the use of lightweight materials. The present activity was carried out in the framework of the Clean Sky European research project ITURB (Optimal High-Lift Turbine Blade Aero-Mechanical Design), aimed at designing and validating a turbine blade for a geared open rotor engine. This two-part paper presents the redesign and the analysis of an optimized rotor blade starting from a baseline configuration, representative of a state-of-the-art LPT rotor. In the redesign activity high standard of performance were required in conjunction with tight mechanical and geometrical constraints. The design strategy was based on an effective multi-objective optimization strategy. The aerodynamic performance were evaluated by means of 3D steady multi-row viscous computations using a two-equation k-w turbulence model. At the same time, the mechanical integrity checks were mainly based on the evaluation of the maximum rotor tensile stress due to centrifugal forces. A simplified and very fast tool was developed in order to compute the centrifugal stress. Finally a response-surface approach based on neural-networks (ANNs) was adopted for the design space exploration. The design was validated by means of a comprehensive experimental campaign carried out in a low-speed turbine single-stage facility. A comparison between the numerical and experimental results are presented in terms of the main rotor performance for a fixed Reynolds number while varying the rotor incidence angle. Unsteady numerical analysis of both the baseline and the optimized blade were carried out by using a multi-equation, transition-sensitive, turbulence model and considering the boundary conditions measured on the test rig.},
note = {GT2016-57746},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Marconcini, Michele; Bianchini, Alessandro; Checcucci, Matteo; Ferrara, Giovanni; Arnone, Andrea; Ferrari, Lorenzo; Biliotti, Davide; Rubino, Dante Tommaso
ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition, vol. 2D: Turbomachinery, Seoul, South Korea, June 13–17, 2016, 2016, ISBN: 978-0-7918-4972-9, (GT2016-57604).
@conference{979,
title = {A 3D Time-Accurate CFD Simulation of the Flow Field Inside a Vaneless Diffuser During Rotating Stall Conditions},
author = {Michele Marconcini and Alessandro Bianchini and Matteo Checcucci and Giovanni Ferrara and Andrea Arnone and Lorenzo Ferrari and Davide Biliotti and Dante Tommaso Rubino},
url = {http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleID=2554875},
doi = {10.1115/GT2016-57604},
isbn = {978-0-7918-4972-9},
year = {2016},
date = {2016-01-01},
booktitle = {ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition},
volume = {2D: Turbomachinery},
pages = {V02DT42A029; 11 pages},
address = {Seoul, South Korea, June 13–17, 2016},
abstract = {An accurate characterization of rotating stall in terms of inception modality, flow structures, and stabilizing force is one of the key goals for high-pressure centrifugal compressors. The unbalanced pressure field that is generated within the diffuser can be in fact connected to a non-negligible aerodynamic force and then to the onset of detrimental sub-synchronous vibrations which can prevent the machine from operating beyond this limit. An inner comprehension on how the induced flow pattern in these conditions affects the performance of the impeller and its mechanical stability can therefore lead to the development of a more effective regulation system able to mitigate the effects of the phenomenon and extend the left-side margin of the operating curve. In the present study, a 3D-unsteady CFD approach was applied to the simulation of a radial stage model including the impeller, the vaneless diffuser and the return channel. Simulations were carried out with the TRAF code of the University of Florence. The tested rotor was an industrial impeller operating at high peripheral Mach number, for which unique experimental pressure measurements, including the spatial reconstruction of the pressure field at the diffuser inlet, were available. The comparison between experiments and simulations showed a good matching and corroborated the CFD capabilities in correctly describing also some of the complex unsteady phenomena taking place in proximity of the left margin of the operating curve.},
note = {GT2016-57604},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Marconcini, Michele; Bianchini, Alessandro; Checcucci, Matteo; Biliotti, Davide; Giachi, Marco; Rubino, Dante Tommaso; Arnone, Andrea; Ferrari, Lorenzo; Ferrara, Giovanni
Estimation of the Aerodynamic Force Induced by Vaneless Diffuser Rotating Stall in Centrifugal Compressor Stages Journal Article
In: Energy Procedia, vol. 101, pp. 734-741, 2016, ISSN: 1876-6102, (ATI 2016 - 71st Conference of the Italian Thermal Machines Engineering Association).
@article{985,
title = {Estimation of the Aerodynamic Force Induced by Vaneless Diffuser Rotating Stall in Centrifugal Compressor Stages},
author = {Michele Marconcini and Alessandro Bianchini and Matteo Checcucci and Davide Biliotti and Marco Giachi and Dante Tommaso Rubino and Andrea Arnone and Lorenzo Ferrari and Giovanni Ferrara},
url = {http://www.sciencedirect.com/science/article/pii/S1876610216313029},
doi = {http://dx.doi.org/10.1016/j.egypro.2016.11.093},
issn = {1876-6102},
year = {2016},
date = {2016-01-01},
journal = {Energy Procedia},
volume = {101},
pages = {734-741},
address = {Turin, Italy, 14-16 September 2016},
abstract = {Rotating stall in centrifugal compressors not only adversely affects the performance before surge, but also can generate high subsynchronous vibrations, marking the minimum flow limit of a machine. Recent works presented an experimental approach to estimate the stall force induced by the unbalanced pressure field in a vaneless diffuser from dynamic pressure measurements. In this study, the results of a 3D-unsteady simulation of a radial stage model were used to estimate the stall force and to compare it with the approximation obtained with an experimental-like approach. Results showed that: a) the experimental approach, using dynamic pressure sensors and an ensemble average approach for transposing data between time and space domains, is thought to give sufficiently accurate results; b) the momentum contribution gives negligible contributions to the intensity of the stall force.},
note = {ATI 2016 - 71st Conference of the Italian Thermal Machines Engineering Association},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Berrino, Marco; Bigoni, Fabio; Simoni, Daniele; Giovannini, Matteo; Marconcini, Michele; Pacciani, Roberto; Bertini, Francesco
Combined Experimental and Numerical Investigations on the Roughness Effects on the Aerodynamic Performances of LPT Blades Journal Article
In: Journal of Thermal Science, vol. 25, pp. 32-42, 2016, ISSN: 1003-2169.
@article{978,
title = {Combined Experimental and Numerical Investigations on the Roughness Effects on the Aerodynamic Performances of LPT Blades},
author = {Marco Berrino and Fabio Bigoni and Daniele Simoni and Matteo Giovannini and Michele Marconcini and Roberto Pacciani and Francesco Bertini},
url = {http://link.springer.com/article/10.1007/s11630-016-0831-5},
doi = {dx.doi.org/10.1007/s11630-016-0831-5},
issn = {1003-2169},
year = {2016},
date = {2016-01-01},
journal = {Journal of Thermal Science},
volume = {25},
pages = {32-42},
abstract = {The aerodynamic performance of a high-load low-pressure turbine blade cascade has been analyzed for three different distributed surface roughness levels (Ra) for steady and unsteady inflows. Results from CFD simulations and experiments are presented for two different Reynolds numbers (300000 and 70000 representative of take-off and cruise conditions, respectively) in order to evaluate the roughness effects for two typical operating conditions. Computational fluid dynamics has been used to support and interpret experimental results, analyzing in detail the flow field on the blade surface and evaluating the non-dimensional local roughness parameters (which were not available from the experimental tests), further contributing to understand how and where roughness have some influence on the aerodynamic performance of the blade. The total pressure distributions in the wake region have been measured by means of a five-hole miniaturized pressure probe for the different flow conditions, allowing the evaluation of profile losses and of their dependence on the surface finish, as well as a direct comparison with the simulations. Results reported in the paper clearly highlight that only at the highest Reynolds number tested (Re=300000) surface roughness have some influence on the blade performance, both for steady and unsteady incoming flows. In this flow condition profile losses grow as the surface roughness increases, while no appreciable variations have been found at the lowest Reynolds number. The boundary layer evolution and the wake structure have shown that this trend is due to a thickening of the suction side boundary layer associated to an anticipation of transition process. On the other side, no effects have been observed on the pressure side boundary layer.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2015
Bellucci, Juri; Rubechini, Filippo; Marconcini, Michele; Arnone, Andrea; Arcangeli, L; Maceli, Nicola; Dossena, Vincenzo
The Influence of Roughness on a High-Pressure Steam Turbine Stage: an Experimental and Numerical Study Journal Article
In: ASME Journal of Engineering for Gas Turbines and Power, vol. 137, no. 012602, pp. 1-9, 2015, ISSN: 0742-4795.
@article{943,
title = {The Influence of Roughness on a High-Pressure Steam Turbine Stage: an Experimental and Numerical Study},
author = {Juri Bellucci and Filippo Rubechini and Michele Marconcini and Andrea Arnone and L Arcangeli and Nicola Maceli and Vincenzo Dossena},
url = {http://gasturbinespower.asmedigitalcollection.asme.org/article.aspx?articleid=1896624},
doi = {dx.doi.org/10.1115/1.4028205},
issn = {0742-4795},
year = {2015},
date = {2015-08-01},
journal = {ASME Journal of Engineering for Gas Turbines and Power},
volume = {137},
number = {012602},
pages = {1-9},
abstract = {This work deals with the influence of roughness on high-pressure steam turbine stages. It is divided in three parts. In the first one, an experimental campaign on a linear cascade is described, in which blade losses are measured for different values of surface roughness and in a range of Reynolds numbers of practical interest. The second part is devoted to the basic aspects of the numerical approach, and consists of a detailed discussion of the roughness models used for computations. The fidelity of such models is then tested against measurements, thus allowing their fine-tuning and proving their reliability. Finally, comprehensive CFD analysis is carried out on a high-pressure stage, in order to investigate the influence of roughness on the losses over the entire stage operating envelope. Unsteady effects that may affect the influence of the roughness, such as the upcoming wakes on the rotor blade, are taken into account, and the impact of transition-related aspects on the losses is discussed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Bellucci, Juri; Rubechini, Filippo; Arnone, Andrea
Some Experiences About the Impact of Unsteadiness in Turbine Flows Conference
ASME Turbo Expo 2015: Turbine Technical Conference and Exposition, Montreal, Canada, 2015, ISBN: 978-079185663-5, (ASME paper GT2015-43122).
@conference{966,
title = {Some Experiences About the Impact of Unsteadiness in Turbine Flows},
author = {Juri Bellucci and Filippo Rubechini and Andrea Arnone},
url = {http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=2427871},
doi = {dx.doi.org/10.1115/GT2015-43122},
isbn = {978-079185663-5},
year = {2015},
date = {2015-06-01},
booktitle = {ASME Turbo Expo 2015: Turbine Technical Conference and Exposition},
address = {Montreal, Canada},
abstract = {This paper discusses the role of the unsteady interaction in turbine design. It focuses on aerodynamic performance, and its main motivation consists in trying to identify some design areas in which some further margins of improvement could be found, provided the designer chooses the proper computational framework. The underlying idea is that the approximations associated with the steady-state picture of a turbine stage might prevent from unlocking the full potential of the stage itself, especially when the design requirements imply a challenging aerodynamics. To this end, three common design topics are presented in which the step from the classical steady-state approach to the time-accurate one unveils relevant issues, which in turn have a relapse on aerodynamic performance: stator/rotor interaction in transonic stages, the choice of the axial gap between stator and rotor, and the choice of the blade count ratio. In all reported cases, significant departures are found between steady and time-averaged results, and the basic fluid mechanisms responsible for them are examined. In particular, an attempt is made to emphasize limitations deriving from of the steady-state picture of the turbine flow field, in order to warn the designer about the possible traps of the steady-state assumption.},
note = {ASME paper GT2015-43122},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Rubechini, Filippo; Marconcini, Michele; Giovannini, Matteo; Bellucci, Juri; Arnone, Andrea
Accounting for Unsteady Interaction in Transonic Stages Journal Article
In: ASME Journal of Engineering for Gas Turbines and Power, vol. 137, no. 052602, pp. 1-9, 2015, ISSN: 0742-4795.
@article{944,
title = {Accounting for Unsteady Interaction in Transonic Stages},
author = {Filippo Rubechini and Michele Marconcini and Matteo Giovannini and Juri Bellucci and Andrea Arnone},
url = {http://gasturbinespower.asmedigitalcollection.asme.org/article.aspx?articleid=1910534&resultClick=3},
doi = {dx.doi.org/10.1115/1.4028667},
issn = {0742-4795},
year = {2015},
date = {2015-05-01},
journal = {ASME Journal of Engineering for Gas Turbines and Power},
volume = {137},
number = {052602},
pages = {1-9},
abstract = {This paper discusses the importance of the unsteady interaction in transonic turbomachinery stages. Although the flow in a turbomachine is inherently unsteady, most current calculations for routine design work exploit the steady-state assumption. In fact, unsteady flow effects are often taken into account for mechanical integrity checks, such as blade flutter or forced response, or heat transfer issues associated with circumferential non-uniformities, whereas steady-state calculations are usually selected for the aerodynamic design. In this work, some cases are discussed in which significant departures are found between steady and time-averaged results, and the basic fluid mechanisms responsible for them are examined. Finally, a current perspective of unsteady Computational Fluid Dynamics (CFD) calculations for the aerodynamic design is given.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Checcucci, Matteo; Schneider, Andrea; Marconcini, Michele; Rubechini, Filippo; Arnone, Andrea; Franco, L De; Coneri, M
A Novel Approach to Parametric Design of Centrifugal Pumps for a Wide Range of Specific Speeds Conference
12th International Symposium on Experimental and Computational Aerothermodynamics of Internal Flows, 13–16 July 2015, Lerici (SP), Italy, 2015, (paper n.121).
@conference{968,
title = {A Novel Approach to Parametric Design of Centrifugal Pumps for a Wide Range of Specific Speeds},
author = {Matteo Checcucci and Andrea Schneider and Michele Marconcini and Filippo Rubechini and Andrea Arnone and L De Franco and M Coneri},
year = {2015},
date = {2015-01-01},
booktitle = {12th International Symposium on Experimental and Computational Aerothermodynamics of Internal Flows},
address = {13–16 July 2015, Lerici (SP), Italy},
abstract = {This work presents a novel approach to parametric design of centrifugal pumps. The outcome is represented by a industrial design tool for a whole family of pumps with single shaft centrifugal impeller, volute, horizontal suction duct and vertical discharge diffuser. In order to reduce costs and time to market for a given design, the main industrial goal consisted in developing a quick and flexible design tool, capable of describing in a continuous manner the whole range of specific speeds of interest. This task should be achieved without reusing or re-adapting existing geometries, as this usually leads to poor performance. To guarantee the continuity over the whole design space, when varying the specific speed, the entire family of pumps had to be geometrically described by means of the same parameterization. By varying all the geometrical parameters, a performance database was created and used to train a meta-model (artificial neural network or support vector machine), which provides a global response surface describing the entire design space for any specific speeds. The response surface is representative of the impeller performance, that were evaluated using a three-dimensional viscous flow solver (TRAF). The accuracy of the meta-model in generating the response surface was evaluated by comparing the operating curves of several geometries with CFD results, demonstrating the ability of the meta-model to well reproduce performance. The flange-to-flange pump performance are then calculated by coupling the response surface for the impeller with correlations for the static components. In this way, the design tool is able to predict the performance of any combination of impeller and static components. The proposed design tool allows the designer to calculate a reliable performance map as a guide to the expected operating flow range and the sensitivity to the choice of the static components, thus assessing the most suitable solution.},
note = {paper n.121},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Giovannini, Matteo; Marconcini, Michele; Rubechini, Filippo; Arnone, Andrea; Bertini, Francesco
Scaling 3D Low-Pressure Turbine Blades for Low-Speed Testing Conference
ASME Turbo Expo 2015: Turbine Technical Conference and Exposition, vol. 2B: Turbomachinery, ASME ASME, Montreal, Canada, June 15–19, 2015, 2015, ISBN: 978-0-7918-5664-2, (ASME paper GT2015–42176).
@conference{964,
title = {Scaling 3D Low-Pressure Turbine Blades for Low-Speed Testing},
author = {Matteo Giovannini and Michele Marconcini and Filippo Rubechini and Andrea Arnone and Francesco Bertini},
url = {http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=2427901&resultClick=3},
doi = {10.1115/GT2015-42176},
isbn = {978-0-7918-5664-2},
year = {2015},
date = {2015-01-01},
booktitle = {ASME Turbo Expo 2015: Turbine Technical Conference and Exposition},
volume = {2B: Turbomachinery},
publisher = {ASME},
address = {Montreal, Canada, June 15–19, 2015},
organization = {ASME},
abstract = {The present activity was carried out in the framework of the Clean Sky European research project ITURB (Optimal High-Lift Turbine Blade Aero-Mechanical Design), aimed at designing and validating a turbine blade for a geared open rotor engine. A cold-flow, large-scale, low-speed (LS) rig was built in order to investigate and validate new design criteria, providing reliable and detailed results while containing costs. This paper presents the design of a LS stage, and describes a general procedure that allows to scale 3D blades for low-speed testing. The design of the stator row was aimed at matching the test-rig inlet conditions and at providing the proper inlet flow field to the blade row. The rotor row was redesigned in order to match the performance of the high-speed one, compensating for both the compressibility effects and different turbine flow paths. The proposed scaling procedure is based on the matching of the 3D blade loading distribution between the real engine environment and the LS facility one, which leads to a comparable behavior of the boundary layer and hence to comparable profile losses. To this end, the datum blade is parameterized, and a neural-networkbased methodology is exploited to guide an optimization process based on 3D RANS computations. The LS stage performance were investigated over a range of Reynolds numbers characteristic of modern low-pressure turbines by using a multi-equation, transition-sensitive, turbulence model.},
note = {ASME paper GT2015–42176},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Pinelli, Lorenzo; Poli, Francesco; Bellucci, Juri; Giovannini, Matteo; Arnone, Andrea
Evaluation of Fast Numerical Methods for Turbomachinery Blade Flutter Analysis Conference
14th International Symposium on Unsteady Aerodynamics, Aeroacoustics and Aeroelasticity of Turbomachines (ISUAAAT), September 8–11, Stockholm, Sweden, 2015, (paper I14-S7-1).
@conference{975,
title = {Evaluation of Fast Numerical Methods for Turbomachinery Blade Flutter Analysis},
author = {Lorenzo Pinelli and Francesco Poli and Juri Bellucci and Matteo Giovannini and Andrea Arnone},
year = {2015},
date = {2015-01-01},
booktitle = {14th International Symposium on Unsteady Aerodynamics, Aeroacoustics and Aeroelasticity of Turbomachines (ISUAAAT)},
address = {September 8–11, Stockholm, Sweden},
abstract = {Different numerical methods for blade flutter analysis were employed to evaluate the flutter stability of a typical low pressure turbine bladerow tested in the context of the European research project FUTURE.
This aeroelastic testcase was extensively studied during the project by a large number of partners, becoming a suitable benchmark to compare numerical techniques for flutter prediction.
In this study, two different uncoupled aeroelastic methods (time-linearized and non-linear) were used to assess the flutter stability. The results highlight a very good agreement between the two approaches even when the non-linear code was applied with some approximation strategies (non viscous endwalls and wall functions).
The two analyzed bladerow configurations (cantilever and interlock) show unstable and stable flutter behavior respectively, and the numerical flutter predictions are in agreement with the experimental evidences obtained during the project.
Finally the two methods were also evaluated in terms of computational time. This is due to the fact that flutter assessment methods are more and more used during the turbomachinery design, even during the bladerow optimization. },
note = {paper I14-S7-1},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
This aeroelastic testcase was extensively studied during the project by a large number of partners, becoming a suitable benchmark to compare numerical techniques for flutter prediction.
In this study, two different uncoupled aeroelastic methods (time-linearized and non-linear) were used to assess the flutter stability. The results highlight a very good agreement between the two approaches even when the non-linear code was applied with some approximation strategies (non viscous endwalls and wall functions).
The two analyzed bladerow configurations (cantilever and interlock) show unstable and stable flutter behavior respectively, and the numerical flutter predictions are in agreement with the experimental evidences obtained during the project.
Finally the two methods were also evaluated in terms of computational time. This is due to the fact that flutter assessment methods are more and more used during the turbomachinery design, even during the bladerow optimization.
Berrino, Marco; Bigoni, Fabio; Simoni, Daniele; Giovannini, Matteo; Marconcini, Michele; Pacciani, Roberto; Bertini, Francesco
Combined Experimental and Numerical Investigations on the Roughness Effects on the Aerodynamic Performances of LPT Blades Conference
12th International Symposium on Experimental and Computational Aerothermodynamics of Internal Flows, 13–16 July 2015, Lerici (SP), Italy, 2015, (paper n. 166).
@conference{973,
title = {Combined Experimental and Numerical Investigations on the Roughness Effects on the Aerodynamic Performances of LPT Blades},
author = {Marco Berrino and Fabio Bigoni and Daniele Simoni and Matteo Giovannini and Michele Marconcini and Roberto Pacciani and Francesco Bertini},
year = {2015},
date = {2015-01-01},
booktitle = {12th International Symposium on Experimental and Computational Aerothermodynamics of Internal Flows},
address = {13–16 July 2015, Lerici (SP), Italy},
abstract = {The aerodynamic performance of a high-load low-pressure turbine blade cascade has been analyzed for three different distributed surface roughness levels (Ra) for steady and unsteady inflows. Results from CFD simulations and experiments are presented for two different Reynolds numbers (300000 and 70000 representative of take-off and cruise conditions, respectively) in order to evaluate the roughness effects for two typical operating conditions. Computational fluid dynamics has been used to support and interpret experimental results, analyzing in detail the flow field on the blade surface and evaluating the non-dimensional local roughness parameters (which were not available from the experimental tests), further contributing to understand how and where roughness have some influence on the aerodynamic performance of the blade. The total pressure distributions in the wake region have been measured by means of a five-hole miniaturized pressure probe for the different flow conditions, allowing the evaluation of profile losses and of their dependence on the surface finish, as well as a direct comparison with the simulations. Results reported in the paper clearly highlight that only at the highest Reynolds number tested (Re=300000) surface roughness have some influence on the blade performance, both for steady and unsteady incoming flows. In this flow condition profile losses grow as the surface roughness increases, while no appreciable variations have been found at the lowest Reynolds number. The boundary layer evolution and the wake structure have shown that this trend is due to a thickening of the suction side boundary layer associated to an anticipation of transition process. On the other side, no effects have been observed on the pressure side boundary layer.},
note = {paper n. 166},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Giovannini, Matteo; Marconcini, Michele; Arnone, Andrea; Dominguez, Alain
A Hybrid Parallelization Strategy of a CFD Code for Turbomachinery Applications Conference
11th European Turbomachinery Conference, March 23-26, Madrid, Spain, 2015, ISSN: 2410-4833, (paper ETC2015-188).
@conference{962,
title = {A Hybrid Parallelization Strategy of a CFD Code for Turbomachinery Applications},
author = {Matteo Giovannini and Michele Marconcini and Andrea Arnone and Alain Dominguez},
url = {http://www.euroturbo.eu/paper/etc2015-188/},
issn = {2410-4833},
year = {2015},
date = {2015-01-01},
booktitle = {11th European Turbomachinery Conference},
address = {March 23-26, Madrid, Spain},
abstract = {This paper presents the serial optimization as well as the parallelization of the TRAF code, a 3D multi-row, multi-block CFD solver for the RANS/URANS equations. The serial optimization was carried out by means of a critical review of the most time-consuming routines in order to exploit vectorization capability of the modern CPUs preserving the code accuracy. The code parallelization was carried out for both distributed and shared memory systems, following the actual trend of computing clusters. Performance were assessed on several architectures ranging from simple multi-core PCs to a small slow-network cluster, and high performance computing (HPC) clusters (CINECA PLX cluster and Intel Grizzly Silver cluster). Code performance are presented and discussed for the pure MPI, pure OpenMP, and hybrid OpenMP-MPI parallelisms considering typical turbomachinery applications: a steady state multi-row compressor analysis and an unsteady computation of a low pressure turbine (LPT) module. Noteworthy, the present paper can provide code developers with relevant guidelines in the selection of the parallelization strategy without asking for a specific background in the parallelization and HPC fields.},
note = {paper ETC2015-188},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
2014
Giovannini, Matteo; Marconcini, Michele; Arnone, Andrea; Bertini, Francesco
Evaluation of Unsteady Computational Fluid Dynamics Models Applied to the Analysis of a Transonic High-Pressure Turbine Stage Journal Article
In: Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, vol. 228, pp. 813-824, 2014, ISSN: 0957-6509.
@article{932,
title = {Evaluation of Unsteady Computational Fluid Dynamics Models Applied to the Analysis of a Transonic High-Pressure Turbine Stage},
author = {Matteo Giovannini and Michele Marconcini and Andrea Arnone and Francesco Bertini},
url = {http://pia.sagepub.com/content/228/7/813},
doi = {dx.doi.org/10.1177/0957650914536170},
issn = {0957-6509},
year = {2014},
date = {2014-11-01},
journal = {Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy},
volume = {228},
pages = {813-824},
abstract = {This paper presents an efficient Phase-Lagged method developed for turbomachinery applications. The method is based on the Generalized-Shape-Correction model. Moving averages techniques as well as double-passage domain formulation were adopted in order to reduce memory requirements and improve the model robustness. The model was used to evaluate the aerodynamic performance of the high pressure transonic turbine stage CT3, experimentally studied at the von Karman Institute for Fluid Dynamics within the EU funded TATEF2 project. Results are discussed and compared with both the available experimental data and the results obtained by means of both steady and unsteady scaled Full-Annulus approaches. Computational requirements of the GSC model are evaluated and presented showing that nowadays unsteady results can be reached at an affordable computational cost.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2013
Bertini, Francesco; Credi, Martina; Marconcini, Michele; Giovannini, Matteo
A Path Toward the Aerodynamic Robust Design of Low Pressure Turbines Journal Article
In: ASME Journal of Turbomachinery, vol. 135, no. 2, pp. 021018, 2013, ISSN: 0889-504X.
@article{938,
title = {A Path Toward the Aerodynamic Robust Design of Low Pressure Turbines},
author = {Francesco Bertini and Martina Credi and Michele Marconcini and Matteo Giovannini},
url = {http://turbomachinery.asmedigitalcollection.asme.org/article.aspx?articleid=1676365},
doi = {10.1115/1.4007519},
issn = {0889-504X},
year = {2013},
date = {2013-11-01},
journal = {ASME Journal of Turbomachinery},
volume = {135},
number = {2},
pages = {021018},
abstract = {Airline companies are continuously demanding lower-fuel-consuming engines and this leads to investigating innovative configurations and to further improving single module performance. In this framework the low pressure turbine (LPT) is known to be a key component since it has a major effect on specific fuel consumption (SFC). Modern aerodynamic design of LPTs for civil aircraft engines has reached high levels of quality, but new engine data, after first engine tests, often cannot achieve the expected performance. Further work on the modules is usually required, with additional costs and time spent to reach the quality level needed to enter into service. The reported study is aimed at understanding some of the causes for this deficit and how to solve some of the highlighted problems. In a real engine, the LPT module works under conditions which differ from those described in the analyzed numerical model: the definition of the geometry cannot be so accurate, a priori unknown values for boundary conditions data are often assumed, complex physical phenomena are seldom taken into account, and operating cycle may differ from the design intent due to a nonoptimal coupling with other engine components. Moreover, variations are present among different engines of the same family, manufacturing defects increase the uncertainty and, finally, deterioration of the components occurs during service. Research projects and several studies carried out by the authors lead to the conclusion that being able to design a module whose performance is less sensitive to variations (robust LPT) brings advantages not only when the engine performs under strong off-design conditions but also, due to the abovementioned unknowns, near the design point as well. Concept and preliminary design phases are herein considered, highlighting the results arising from sensibility studies and their impact on the final designed robust configuration. Module performance is afterward estimated using a statistical approach.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Rubechini, Filippo; Marconcini, Michele; Arnone, Andrea; Greco, Alberto Scotti Del; Biagi, Roberto
Special Challenges in the Computational Fluid Dynamics Modeling of Transonic Turbo-Expanders Journal Article
In: ASME Journal of Engineering for Gas Turbines and Power, vol. 135, no. 10, pp. 102701, 2013, ISSN: 0742-4795, (ASME paper GT2013-95554).
@article{934,
title = {Special Challenges in the Computational Fluid Dynamics Modeling of Transonic Turbo-Expanders},
author = {Filippo Rubechini and Michele Marconcini and Andrea Arnone and Alberto Scotti Del Greco and Roberto Biagi},
url = {http://gasturbinespower.asmedigitalcollection.asme.org/article.aspx?articleid=1734459},
doi = {10.1115/1.4025034},
issn = {0742-4795},
year = {2013},
date = {2013-08-01},
journal = {ASME Journal of Engineering for Gas Turbines and Power},
volume = {135},
number = {10},
pages = {102701},
publisher = {ASME},
abstract = {High pressure ratio turbo-expanders often put a strain on computational fluid dynamics (CFD) modeling. First of all, the working fluid is usually characterized by significant departures from the ideal behavior, thus requiring the adoption of a reliable real gas model. Moreover, supersonic flow conditions are typically reached at the nozzle vanes discharge, thus involving the formation of a shock pattern, which is in turn responsible for a strong unsteady interaction with the wheel blades. Under such circumstances, performance predictions based on classical perfect gas, steady-state calculations can be very poor. While reasonably accurate real gas models are nowadays available in most flow solvers, unsteady real gas calculations still struggle to become an affordable tool for investigating turbo-expanders. However, it is emphasized in this work how essential the adoption of a time-accurate analysis can be for accurate performance estimations. The present paper is divided in two parts. In the first part, the computational framework is validated against on-site measured performance from an existing power plant equipped with a variable-geometry nozzled turbo-expander, for different nozzle positions, and in design and off-design conditions. The second part of the paper is devoted to the detailed discussion of the unsteady interaction between the nozzle shock waves and the wheel flow field. Furthermore, an attempt is made to identify the key factors responsible for the unsteady interaction and to outline an effective way to reduce it.},
note = {ASME paper GT2013-95554},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Rubechini, Filippo; Marconcini, Michele; Arnone, Andrea; Greco, Alberto Scotti Del; Biagi, Roberto
Special Challenges in the CFD Modeling of Transonic Turbo-Expanders Proceeding
ASME, San Antonio, Texas, USA, June 3–7, 2013, vol. 6C: Turbomachinery, 2013, ISBN: 978-0-7918-5524-9, (ASME paper GT2013-95554).
@proceedings{954,
title = {Special Challenges in the CFD Modeling of Transonic Turbo-Expanders},
author = {Filippo Rubechini and Michele Marconcini and Andrea Arnone and Alberto Scotti Del Greco and Roberto Biagi},
url = {http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=1776645&resultClick=1},
doi = {dx.doi.org/10.1115/GT2013-95554},
isbn = {978-0-7918-5524-9},
year = {2013},
date = {2013-06-01},
journal = {ASME Turbo Expo 2013: Turbine Technical Conference and Exposition},
volume = {6C: Turbomachinery},
pages = {V06CT40A016; 10 pages},
publisher = {ASME},
address = {San Antonio, Texas, USA, June 3–7, 2013},
abstract = {High pressure ratio turbo-expanders often put a strain on CFD modeling. First of all, the working fluid is usually characterized by significant departures from the ideal behavior, thus requiring the adoption of a reliable real gas model. Moreover, supersonic flow conditions are typically reached at the nozzle vanes discharge, thus involving the formation of a shock pattern, which is in turn responsible for a strong unsteady interaction with the wheel blades. Under such circumstances, performance predictions based on classical perfect gas, steady-state calculations can be very poor. While reasonably accurate real gas models are nowadays available in most flow solvers, unsteady real gas calculations still struggle to become an affordable tool for investigating turbo-expanders. However, it is emphasized in this work how essential the adoption of a time-accurate analysis can be for accurate performance estimations. The present paper is divided in two parts. In the first part, the computational framework is validated against on-site measured performance from an existing power plant equipped with a variable-geometry nozzled turbo-expander, for different nozzle positions, and in design and off-design conditions. The second part of the paper is devoted to the detailed discussion of the unsteady interaction between the nozzle shock waves and the wheel flow field. Furthermore, an attempt is made to identify the key factors responsible for the unsteady interaction and to outline an effective way to reduce it.},
note = {ASME paper GT2013-95554},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
Giovannini, Matteo; Marconcini, Michele; Arnone, Andrea; Bertini, Francesco
Evaluation of Unsteady CFD Models Applied to the Analysis of a Transonic HP Turbine Stage Proceeding
Lappeenranta, Finland, 2013, ISBN: 978-952-265-385-7.
@proceedings{945,
title = {Evaluation of Unsteady CFD Models Applied to the Analysis of a Transonic HP Turbine Stage},
author = {Matteo Giovannini and Michele Marconcini and Andrea Arnone and Francesco Bertini},
isbn = {978-952-265-385-7},
year = {2013},
date = {2013-04-01},
journal = {10th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics (ETC 2013)},
pages = {840-853},
address = {Lappeenranta, Finland},
abstract = {This paper presents an efficient textquotedblleftPhase-Laggedtextquotedblright method developed for turbomachinery applications. The method is based on the Generalized-Shape-Correction model. Moving averages techniques as well as double-passage domain formulation were adopted in order to reduce memory requirements and improve the model robustness. The model was used to evaluate the aerodynamic performance of the high pressure transonic turbine stage CT3, experimentally studied at the von Karman Institute for Fluid Dynamics within the EU funded TATEF2 project. Results are discussed and compared with both the available experimental data and the results obtained by means of both steady and unsteady scaled Full-Annulus approaches. Computational requirements of the GSC model are evaluated and presented showing that nowadays unsteady results can be reached at an affordable computational cost.},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
Bertini, Francesco; Ampellio, E; Marconcini, Michele; Giovannini, Matteo
ASME, San Antonio, TX, USA, June 3–7, vol. 6B: Turbomachinery, 2013, ISBN: 978-0-7918-5523-2, (ASME paper GT2013-94849).
@proceedings{935,
title = {A Critical Numerical Review of Loss Correlation Models and Smith Diagram for Modern Low Pressure Turbine Stages},
author = {Francesco Bertini and E Ampellio and Michele Marconcini and Matteo Giovannini},
url = {http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleID=1776565},
doi = {10.1115/GT2013-94849},
isbn = {978-0-7918-5523-2},
year = {2013},
date = {2013-01-01},
journal = {ASME Turbo Expo 2013: Turbine Technical Conference and Exposition},
volume = {6B: Turbomachinery},
pages = {V06BT37A018-; 14 pages},
publisher = {ASME},
address = {San Antonio, TX, USA, June 3–7},
abstract = {The Smith diagram, originally published in 1965, has been largely exploited as a preliminary design (PD) tool for axial turbines. Currently, it is applied to aeronautical Low Pressure Turbines (LPTs) in order to define basic characteristics during the feasibility study and to compare different configurations. The Smith diagram represents a correlation of stage performance (η) as function of flow coefficient (φ) and loading factor (ψ), but it does not take into account the effects of some important input parameters (single contributions of loss, Reynolds number, Aspect Ratio, Rotor Tip Clearance (RTC)) and does not report some key design outputs (deflections (δ), profile weights and stresses), which have also a direct relation with the configuration position on the Smith diagram. This study employs meanline analyses incorporating two traditional loss correlation models used in the turbine field (Craig and Cox, Kacker and Okapuu) to compare results with the original Smith diagram. The correlation approach allows one to obtain other important multidisciplinary information (primarily aero-mechanical) which was previously absent, which leads to some strategic design achievements. The investigation process is based on a reference two-stage turbine properly set to match specific operating points on the Smith diagram. Several three-dimensional blade geometries have been designed and then detailed 3D CFD analyses have been performed in order to acquire confidence with respect to the meanline results. This research adds additional important information for turbine module design to the Smith chart and allows for a numerical revision of the diagram itself, fine tuning it with data obtained from the analyses of modern blades optimized for high stage performance. Finally numerically-based loss predictors, broadly applicable to LPTs during optimization procedures before detailed CFD analyses, are presented and discussed.},
note = {ASME paper GT2013-94849},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
2012
Marconcini, Michele; Rubechini, Filippo; Pacciani, Roberto; Arnone, Andrea; Bertini, Francesco
Redesign of High-Lift Low Pressure Turbine Airfoils For Low Speed Testing Journal Article
In: ASME Journal of Turbomachinery, vol. 134, pp. 051017, 2012, ISSN: 0889-504X.
@article{MRPAB12,
title = {Redesign of High-Lift Low Pressure Turbine Airfoils For Low Speed Testing},
author = {Michele Marconcini and Filippo Rubechini and Roberto Pacciani and Andrea Arnone and Francesco Bertini},
url = {http://turbomachinery.asmedigitalcollection.asme.org/article.aspx?articleid=1485158},
doi = {dx.doi.org/10.1115/1.4004474},
issn = {0889-504X},
year = {2012},
date = {2012-09-01},
journal = {ASME Journal of Turbomachinery},
volume = {134},
pages = {051017},
publisher = {ASME},
abstract = {Low pressure turbine airfoils of the present generation usually operate at subsonic conditions, with exit Mach numbers of about 0.6. To reduce the costs of experimental programs it can be convenient to carry out measurements in low speed tunnels in order to determine the cascades performance. Generally speaking, low speed tests are usually carried out on airfoils with modified shape, in order to compensate for the effects of compressibility. A scaling procedure for high-lift, low pressure turbine airfoils to be studied in low speed conditions is presented and discussed. The proposed procedure is based on the matching of a prescribed blade load distribution between the low speed airfoil and the actual one. Such a requirement is fulfilled via an Artificial Neural Network (ANN) methodology and a detailed parameterization of the airfoil. A RANS solver is used to guide the redesign process. The comparison between high and low speed profiles is carried out, over a wide range of Reynolds numbers, by using a novel three-equation, transition-sensitive, turbulence model. Such a model is based on the coupling of an additional transport equation for the so-called laminar kinetic energy (LKE) with the Wilcox k-omega model and it has proven to be effective for transitional, separated-flow configurations of high-lift cascade flows.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Bertini, Francesco; Credi, Martina; Marconcini, Michele; Giovannini, Matteo
A Path Towards the Aerodynamic Robust Design of Low Pressure Turbines Proceeding
ASME, Copenhagen, Denmark, June 11–15, 2012, vol. 8: Turbomachinery, Parts A, B, and C, 2012, ISBN: 978-0-7918-4474-8, (ASME paper GT2012-69456).
@proceedings{953,
title = {A Path Towards the Aerodynamic Robust Design of Low Pressure Turbines},
author = {Francesco Bertini and Martina Credi and Michele Marconcini and Matteo Giovannini},
url = {http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=1694976&resultClick=1},
doi = {dx.doi.org/10.1115/GT2012-69456},
isbn = {978-0-7918-4474-8},
year = {2012},
date = {2012-06-01},
journal = {ASME Turbo Expo 2012: Turbine Technical Conference and Exposition},
volume = {8: Turbomachinery, Parts A, B, and C},
pages = {pp. 1497-1507},
publisher = {ASME},
address = {Copenhagen, Denmark, June 11–15, 2012},
abstract = {Airline companies are continuously demanding lower-fuel-consuming engines and this leads to investigating innovative configurations and to further improving single module performance. In this framework the Low Pressure Turbine (LPT) is known to be a key component since it has a major effect on specific fuel consumption (SFC).
Modern aerodynamic design of LPTs for civil aircraft engines has reached high levels of quality, but new engine data, after first engine tests, often cannot achieve the expected performance. Further work on the modules is usually required, with additional costs and time spent to reach the quality level needed to enter in service. The reported study is aimed at understanding some of the causes for this deficit and how to solve some of the highlighted problems.
In a real engine, the LPT module works under conditions which differ from those described in the analyzed numerical model: the definition of the geometry cannot be so accurate, a priori unknown values for boundary conditions data are often assumed, complex physical phenomena are seldom taken into account, operating cycle may differ from the design intent due to a non-optimal coupling with other engine components. Moreover, variations are present among different engines of the same family, manufacturing defects increase the uncertainty and, finally, deterioration of the components occurs during service.
Research projects and several studies carried out by the authors lead to the conclusion that being able to design a module whose performance is less sensitive to variations (Robust LPT) brings advantages not only when the engine performs under strong off-design conditions but also, due to the abovementioned unknowns, near the design point as well.
Concept and Preliminary Design phases are herein considered, highlighting the results arising from sensibility studies and their impact on the final designed robust configuration. Module performance is afterward estimated using a statistical approach.},
note = {ASME paper GT2012-69456},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
Modern aerodynamic design of LPTs for civil aircraft engines has reached high levels of quality, but new engine data, after first engine tests, often cannot achieve the expected performance. Further work on the modules is usually required, with additional costs and time spent to reach the quality level needed to enter in service. The reported study is aimed at understanding some of the causes for this deficit and how to solve some of the highlighted problems.
In a real engine, the LPT module works under conditions which differ from those described in the analyzed numerical model: the definition of the geometry cannot be so accurate, a priori unknown values for boundary conditions data are often assumed, complex physical phenomena are seldom taken into account, operating cycle may differ from the design intent due to a non-optimal coupling with other engine components. Moreover, variations are present among different engines of the same family, manufacturing defects increase the uncertainty and, finally, deterioration of the components occurs during service.
Research projects and several studies carried out by the authors lead to the conclusion that being able to design a module whose performance is less sensitive to variations (Robust LPT) brings advantages not only when the engine performs under strong off-design conditions but also, due to the abovementioned unknowns, near the design point as well.
Concept and Preliminary Design phases are herein considered, highlighting the results arising from sensibility studies and their impact on the final designed robust configuration. Module performance is afterward estimated using a statistical approach.
Rubechini, Filippo; Schneider, Andrea; Arnone, Andrea; Cecchi, Stefano; Malavasi, F
A Redesign Strategy to Improve the Efficiency of a 17-Stage Steam Turbine Journal Article
In: ASME Journal of Turbomachinery, vol. 134, pp. 031021, 2012, ISSN: 0889-504X.
@article{RSACM12,
title = {A Redesign Strategy to Improve the Efficiency of a 17-Stage Steam Turbine},
author = {Filippo Rubechini and Andrea Schneider and Andrea Arnone and Stefano Cecchi and F Malavasi},
url = {http://turbomachinery.asmedigitalcollection.asme.org/article.aspx?articleid=1468843},
doi = {10.1115/1.4003082},
issn = {0889-504X},
year = {2012},
date = {2012-05-01},
journal = {ASME Journal of Turbomachinery},
volume = {134},
pages = {031021},
abstract = {A three-dimensional Reynolds averaged Navier–Stokes solver was applied to the aerodynamic redesigning of a 17-stage steam turbine. The redesign procedure was divided into three steps. In the first one, a single embedded stage was considered, and an optimization of stator lean and rotor twist was carried out by applying suitable repeating inlet/outlet boundary conditions. In the second step, a proper geometrical transformation between the original reference stage and the optimized one was identified and then applied to all other turbine stages, thus leading to a first approximation of the redesigned turbine. Finally, a neural-network-based refinement of the stator and rotor twist of each stage was performed to account for its actual position and operating conditions within the meridional channel. In this work, a detailed description of the redesign procedure is provided, and the aerodynamic characteristics of the optimized geometry are discussed and compared with the original ones.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Marconcini, Michele; Rubechini, Filippo; Arnone, Andrea; Greco, Alberto Scotti Del; Biagi, Roberto
ASME, Copenhagen, Denmark, 11-15 June, vol. 8: Turbomachinery, Parts A, B, and C, 2012, ISBN: 978-0-7918-4474-8, (ASME paper GT2012-69409.).
@proceedings{921,
title = {Aerodynamic Investigation of a High Pressure Ratio Turbo-Expander for Organic Rankine Cycle Applications},
author = {Michele Marconcini and Filippo Rubechini and Andrea Arnone and Alberto Scotti Del Greco and Roberto Biagi},
url = {http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=1695157},
doi = {10.1115/GT2012-69409},
isbn = {978-0-7918-4474-8},
year = {2012},
date = {2012-01-01},
journal = {ASME Turbo Expo 2012: Turbine Technical Conference and Exposition},
volume = {8: Turbomachinery, Parts A, B, and C},
pages = {847-856},
publisher = {ASME},
address = {Copenhagen, Denmark, 11-15 June},
abstract = {The design of radial-inflow turbines usually relies on one-dimensional or mean-line methods. While these approaches have so far proven to be quite effective, they can not assist the designer in coping with some important issues, such as mechanical integrity and complex flow features. Turbo-expanders are in general characterized by fully three-dimensional flow fields, strongly influenced by viscous effects and passage curvature. In particular, for high pressure ratio applications, such as in organic Rankine cycles, supersonic flow conditions are likely to be reached, thus involving the formation of a shock pattern which governs the interaction between nozzle and wheel components. The nozzle shock waves are periodically chopped by the impeller leading edge, and the resulting unsteady interaction is of primary concern for both mechanical integrity and aerodynamic performance. This work is focused on the aerodynamic issues, and addresses some key aspects of the CFD modelling in the numerical analysis of turbo-expanders. Calculations were carried out by adopting models with increasing level of complexity, from the classical steady-state approach to the full-stage, time-accurate one. Results are compared in details, and the impact of the computational model on the aerodynamic performance estimation is discussed.},
note = {ASME paper GT2012-69409.},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
Pacciani, Roberto; Rubechini, Filippo; Arnone, Andrea; Lutum, E
Calculation of Steady and Periodic Unsteady Blade Surface Heat Transfer in Separated Transitional Flow Journal Article
In: ASME Journal of Turbomachinery, vol. 134, pp. 061037, 2012, ISSN: 0889-504X.
@article{PRAL12,
title = {Calculation of Steady and Periodic Unsteady Blade Surface Heat Transfer in Separated Transitional Flow},
author = {Roberto Pacciani and Filippo Rubechini and Andrea Arnone and E Lutum},
url = {http://turbomachinery.asmedigitalcollection.asme.org/article.aspx?articleid=1485227},
doi = {http://dx.doi.org/10.1115/1.4006312},
issn = {0889-504X},
year = {2012},
date = {2012-01-01},
journal = {ASME Journal of Turbomachinery},
volume = {134},
pages = {061037},
publisher = {ASME},
abstract = {this work, aerothermal investigations of a highly loaded HP turbine blade are presented. The purpose of such investigations is to improve the physical understanding of the heat transfer in separated flow regions, with the final goal of optimizing cooling configurations for aerodynamically highly loaded turbine designs. The analysis is focused on the T120 cascade, that was recently tested experimentally in the framework of the European project AITEB-2 (Aero-thermal Investigation of Turbine Endwalls and Blades). Such a cascade has a relatively low solidity that is responsible for the formation of a laminar separation bubble on the suction side of the blade. Separated-flow transition and transonic conditions downstream of the throat result in a flow configuration that is very challenging for traditional RANS solvers. Moreover, the separated flow transition pattern was found to have a strong impact on both the aerodynamic and thermal aspects. The study was carried out using a novel three-equation, transition-sensitive, turbulence model. It is based on the coupling of an additional transport equation for the laminar kinetic energy to the Wilcox k -omega model. Such an approach allows one to take into account the increase of the nonturbulent fluctuations in the pretransitional and transitional region. Comprehensive aerodynamic and heat transfer measurements were available for comparison purposes. In particular, heat transfer measurements cover different Mach and Reynolds numbers, in both steady and periodic unsteady inflow conditions. A detailed comparison between measurements and computations is presented, and the impact of transition-related aspects on the surface heat transfer is discussed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2011
Rubechini, Filippo; Schneider, Andrea; Arnone, Andrea; `a, Federico Dacc; Canelli, C; Garibaldi, P
Aerodynamic Redesigning of an Industrial Gas Turbine Proceeding
ASME, Vancouver, BC, Canada, 6-10 June, vol. 7: Turbomachinery, Parts A, B, and C, 2011, ISBN: 978-0-7918-5467-9.
@proceedings{RSADCG11,
title = {Aerodynamic Redesigning of an Industrial Gas Turbine},
author = {Filippo Rubechini and Andrea Schneider and Andrea Arnone and Federico Dacc `a and C Canelli and P Garibaldi},
url = {http://link.aip.org/link/abstract/ASMECP/v2011/i54679/p1387/s1},
doi = {dx.doi.org/10.1115/GT2011-46258},
isbn = {978-0-7918-5467-9},
year = {2011},
date = {2011-01-01},
journal = {ASME Turbo Expo},
volume = {7: Turbomachinery, Parts A, B, and C},
pages = {1387-1394},
publisher = {ASME},
address = {Vancouver, BC, Canada, 6-10 June},
abstract = {This paper deals with the aerodynamic redesigning of a four-stage heavy-duty gas turbine. Traditional design tools, such as through-flow methods, as well as more sophisticated tools, such as three-dimensional RANS computations, were applied in subsequent steps according to a given hierarchical criterion. Each design or analysis tool was coupled with modern optimization techniques, and the overall redesign procedure relies on a neural-network-based approach aimed at maximizing the turbinetextquoterights power output while satisfying geometrical and mechanical constraints. A detailed description of the redesign procedure is provided, and the aerodynamic characteristics of the optimized geometry are discussed and compared to the original ones.},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
Checcucci, Matteo; Sazzini, F; Marconcini, Michele; Arnone, Andrea; Coneri, M; Franco, L De; Toselli, M
Assessment of a Neural-Network-Based Optimization Tool: a Low Specific-Speed Impeller Application Journal Article
In: International Journal of Rotating Machinery, vol. 2011, no. ID 817547, pp. 1-11, 2011, ISSN: 1023-621X.
@article{CSMACDT11,
title = {Assessment of a Neural-Network-Based Optimization Tool: a Low Specific-Speed Impeller Application},
author = {Matteo Checcucci and F Sazzini and Michele Marconcini and Andrea Arnone and M Coneri and L De Franco and M Toselli},
url = {http://www.hindawi.com/journals/ijrm/2011/817547/},
doi = {10.1155/2011/817547},
issn = {1023-621X},
year = {2011},
date = {2011-01-01},
journal = {International Journal of Rotating Machinery},
volume = {2011},
number = {ID 817547},
pages = {1-11},
publisher = {Hindawi Publishing Corporation},
abstract = {This work provides a detailed description of the fluid dynamic design of a low specific-speed industrial pump centrifugal impeller. The main goal is to guarantee a certain value of the specific speed number at the design flow rate, while satisfying geometrical constraints and industrial feasibility. The design procedure relies on a modern optimization technique such as an Artificial-Neural-Network-based approach (ANN). The impeller geometry is parameterized in order to allow geometrical variations over a large design space. The computational framework suitable for pump optimization is based on a fully viscous three-dimensional numerical solver, used for the impeller analysis. The performance prediction of the pump has been obtained by coupling the CFD analysis with a 1D correlation tool, which accounts for the losses due to the other components not included in the CFD domain. Due to both manufacturing and geometrical constraints, two different optimized impellers with 3 and 5 blades have been developed, with the performance required in terms of efficiency and suction capability. The predicted performance of both configurations were compared with the measured head and efficiency characteristics.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2010
Pacciani, Roberto; Rubechini, Filippo; Arnone, Andrea; Lutum, E
ASME, Glasgow, UK, June 14–18, 2010, vol. 4: Heat Transfer, Parts A and B, 2010, ISBN: 978-0-7918-4399-4, (Paper No. GT2010-23275).
@proceedings{948,
title = {Calculation of Steady and Periodic Unsteady Blade Surface Heat Transfer in Separated Transitional Flow},
author = {Roberto Pacciani and Filippo Rubechini and Andrea Arnone and E Lutum},
url = {http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=1608834&resultClick=3},
doi = {10.1115/GT2010-23275},
isbn = {978-0-7918-4399-4},
year = {2010},
date = {2010-06-01},
journal = {ASME Turbo Expo 2010: Power for Land, Sea, and Air},
volume = {4: Heat Transfer, Parts A and B},
pages = {891-900},
publisher = {ASME},
address = {Glasgow, UK, June 14–18, 2010},
abstract = {In this work aerothermal investigations of a highly loaded HP turbine blade are presented. The purpose of such investigations is to improve the physical understanding of the heat transfer in separated flow regions, with the final goal of optimizing cooling configurations for aerodynamically highly loaded turbine designs. The analysis is focused on the T120 cascade, that was recently tested experimentally in the framework of the European project AITEB-2 (Aero-thermal Investigation of Turbine Endwalls and Blades). Such a cascade has a relatively low solidity that is responsible for the formation of a laminar separation bubble on the suction side of the blade. Separated-flow transition and transonic conditions downstream of the throat result in a flow configuration that is very challenging for traditional RANS solvers. Moreover, the separated flow transition pattern was found to have a strong impact on both the aerodynamic and thermal aspects. The study was carried out using a novel three-equation, transition-sensitive, turbulence model. It is based on the coupling of an additional transport equation for the laminar kinetic energy to the Wilcox k–ω model. Such an approach allows one to take into account the increase of the non-turbulent fluctuations in the pre-transitional and transitional region. Comprehensive aerodynamic and heat transfer measurements were available for comparison purposes. In particular, heat transfer measurements cover different Mach and Reynolds numbers, in both steady and periodic unsteady inflow conditions. A detailed comparison between measurements and computations is presented, and the impact of transition-related aspects on the surface heat transfer is discussed.},
note = {Paper No. GT2010-23275},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
Marconcini, Michele; Rubechini, Filippo; Pacciani, Roberto; Arnone, Andrea; Bertini, Francesco
Redesign of High-Lift LP-Turbine Airfoils for Low Speed Testing Proceeding
ASME, Glasgow, UK, June 14–18, 2010, vol. 7: Turbomachinery, Parts A, B, and C, 2010, ISBN: 978-0-7918-4402-1, (Paper GT2010-23284).
@proceedings{949,
title = {Redesign of High-Lift LP-Turbine Airfoils for Low Speed Testing},
author = {Michele Marconcini and Filippo Rubechini and Roberto Pacciani and Andrea Arnone and Francesco Bertini},
url = {http://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleid=1609849&resultClick=3},
doi = {dx.doi.org/10.1115/GT2010-23284},
isbn = {978-0-7918-4402-1},
year = {2010},
date = {2010-06-01},
journal = {ASME Turbo Expo 2010: Power for Land, Sea, and Air},
volume = {7: Turbomachinery, Parts A, B, and C},
pages = {909-918},
publisher = {ASME},
address = {Glasgow, UK, June 14–18, 2010},
abstract = {Low pressure turbine airfoils of the present generation usually operate at subsonic conditions, with exit Mach numbers of about 0.6. To reduce the costs of experimental programs it can be convenient to carry out measurements in low speed tunnels in order to determine the cascades performance. Generally speaking, low speed tests are usually carried out on airfoils with modified shape, in order to compensate for the effects of compressibility. A scaling procedure for high-lift, low pressure turbine airfoils to be studied in low speed conditions is presented and discussed. The proposed procedure is based on the matching of a prescribed blade load distribution between the low speed airfoil and the actual one. Such a requirement is fulfilled via an Artificial Neural Network (ANN) methodology and a detailed parameterization of the airfoil. A RANS solver is used to guide the redesign process. The comparison between high and low speed profiles is carried out, over a wide range of Reynolds numbers, by using a novel three-equation, transition-sensitive, turbulence model. Such a model is based on the coupling of an additional transport equation for the so-called laminar kinetic energy (LKE) with the Wilcox k–ω model and it has proven to be effective for transitional, separated-flow configurations of high-lift cascade flows.},
note = {Paper GT2010-23284},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}
Marconcini, Michele; Rubechini, Filippo; Arnone, Andrea; Ibaraki, Seiichi
Numerical Analysis of the Vaned Diffuser of a Transonic Centrifugal Compressor Journal Article
In: ASME Journal of Turbomachinery, vol. 132, no. 4, pp. 041012, 2010, ISSN: 0889-504X.
@article{MRAI10,
title = {Numerical Analysis of the Vaned Diffuser of a Transonic Centrifugal Compressor},
author = {Michele Marconcini and Filippo Rubechini and Andrea Arnone and Seiichi Ibaraki},
url = {http://turbomachinery.asmedigitalcollection.asme.org/article.aspx?articleid=1468248},
doi = {10.1115/1.2988481},
issn = {0889-504X},
year = {2010},
date = {2010-01-01},
journal = {ASME Journal of Turbomachinery},
volume = {132},
number = {4},
pages = {041012},
abstract = {A three-dimensional Navier-Stokes solver is used to investigate the flow field of a high pressure ratio centrifugal compressor for turbocharger applications. Such a compressor consists of a double-splitter impeller followed by a vaned diffuser. Particular attention is focused on the analysis of the vaned diffuser, designed for high subsonic inlet conditions. The diffuser is characterized by a complex three-dimensional flow field, and influenced by the unsteady interaction with the impeller. Detailed Particle Image Velocimetry (PIV) flow measurements within the diffuser are available for comparison.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}