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}
}
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.
Bertini, Francesco; Credi, Martina; Marconcini, Michele; Giovannini, Matteo
A Path Towards the Aerodynamic Robust Design of Low Pressure Turbines Proceedings
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}
}
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.
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}
}
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.
Marconcini, Michele; Rubechini, Filippo; Arnone, Andrea; Greco, Alberto Scotti Del; Biagi, Roberto
Aerodynamic Investigation of a High Pressure Ratio Turbo-Expander for Organic Rankine Cycle Applications Proceedings
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}
}
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.
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}
}
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.
2011
Rubechini, Filippo; Schneider, Andrea; Arnone, Andrea; `a, Federico Dacc; Canelli, C; Garibaldi, P
Aerodynamic Redesigning of an Industrial Gas Turbine Proceedings
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}
}
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.
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}
}
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.
2010
Pacciani, Roberto; Rubechini, Filippo; Arnone, Andrea; Lutum, E
Calculation of Steady and Periodic Unsteady Blade Surface Heat Transfer in Separated Transitional Flow Proceedings
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}
}
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.
Marconcini, Michele; Rubechini, Filippo; Pacciani, Roberto; Arnone, Andrea; Bertini, Francesco
Redesign of High-Lift LP-Turbine Airfoils for Low Speed Testing Proceedings
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}
}
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.
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}
}
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.