Large eddy simulations of a linear low-pressure turbine cascade with the T106A profile and different surface roughness patches were carried out. The aim was to investigate the effects on the laminar and turbulent boundary layer on the blade suction surface. Two different approaches were used to represent the roughness patches. Firstly, a forcing model, reducing the computational costs compared to fully resolved roughness surfaces, was incorporated. Secondly, an immersed boundary method representing an as-cast roughness surface was used, for a more detailed analysis of flow mechanisms over roughness. It was found that the roughness model was able to induce boundary layer transition and alter the turbulent boundary layer, with the results in line with findings in the literature. The instantaneous flow data at different time instants of the as-cast roughness case showed the development of streaks due to distinct roughness peaks, resulting in highly uneven transition positions across the spanwise direction.
{"title":"Large Eddy Simulations of a Low-Pressure Turbine: Roughness Modeling and the Effects on Boundary Layer Transition and Losses","authors":"F. Hammer, N. Sandham, R. Sandberg","doi":"10.1115/GT2018-75796","DOIUrl":"https://doi.org/10.1115/GT2018-75796","url":null,"abstract":"Large eddy simulations of a linear low-pressure turbine cascade with the T106A profile and different surface roughness patches were carried out. The aim was to investigate the effects on the laminar and turbulent boundary layer on the blade suction surface. Two different approaches were used to represent the roughness patches. Firstly, a forcing model, reducing the computational costs compared to fully resolved roughness surfaces, was incorporated. Secondly, an immersed boundary method representing an as-cast roughness surface was used, for a more detailed analysis of flow mechanisms over roughness.\u0000 It was found that the roughness model was able to induce boundary layer transition and alter the turbulent boundary layer, with the results in line with findings in the literature. The instantaneous flow data at different time instants of the as-cast roughness case showed the development of streaks due to distinct roughness peaks, resulting in highly uneven transition positions across the spanwise direction.","PeriodicalId":388234,"journal":{"name":"Volume 2B: Turbomachinery","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121798697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A simulation of the flow through a four-stage low pressure turbine (LPT) of an aero-engine is performed using an eddy-viscosity based RANS model. An analysis of secondary flow details in the vicinity of endwalls and strut surface is performed. An interaction of wakes generated by the swirler vanes and end-wall boundary layers is also studied. The CFD results are compared with own test rig data of LPT obtained in Polonia Aero Lab in Zielonka (Poland). Global flow parameters were reproduced in good agreement with experiment (difference less than 1.5%). Satisfactory agreement between measured and predicted pressure distribution on the surface of inlet strut has been obtained.
{"title":"Prediction of Secondary Flow Features in a Low Pressure Turbine","authors":"P. Jonak, T. Borzęcki, M. Konopa, S. Kubacki","doi":"10.1115/GT2018-75673","DOIUrl":"https://doi.org/10.1115/GT2018-75673","url":null,"abstract":"A simulation of the flow through a four-stage low pressure turbine (LPT) of an aero-engine is performed using an eddy-viscosity based RANS model. An analysis of secondary flow details in the vicinity of endwalls and strut surface is performed. An interaction of wakes generated by the swirler vanes and end-wall boundary layers is also studied. The CFD results are compared with own test rig data of LPT obtained in Polonia Aero Lab in Zielonka (Poland). Global flow parameters were reproduced in good agreement with experiment (difference less than 1.5%). Satisfactory agreement between measured and predicted pressure distribution on the surface of inlet strut has been obtained.","PeriodicalId":388234,"journal":{"name":"Volume 2B: Turbomachinery","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123668809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Centrifugal compressors are used in large water-cooled chillers for Heating, Ventilating, and Air Conditioning (HVAC) applications. A water-cooled chiller is one of the largest power consumers in a building HVAC system. One way of reducing the power consumption is to use an economizer cycle. In a typical economizer cycle, the vapor from the economizer (located between the condenser and the evaporator) is injected into the inlet of the compressor second stage of a multistage machine. The added cost and complexity of a two-stage compressor can be reduced with a single-stage design. To achieve the best of a single-stage design along with the benefit of an economizer cycle, a novel single-stage compressor with an economizer gas injection into the stage is analyzed using computational fluid dynamics methods. The compressor is designed with an unshrouded impeller and a pipe diffuser. Design parameters such as injection location, angle and size were analyzed to maximize the cycle benefit and achieve a minimum loss in compressor efficiency. Experiments were carried out in a real gas test rig using R134a refrigerant to validate the analytical results. This paper presents the concept and computational results of the parametric study, along with the test rig details and results.
{"title":"Analytical and Experimental Results of a Novel Single-Stage Centrifugal Compressor With Economizer Injection","authors":"W. Cousins, Lei Yu, M. SishtlaVishnu, F. Shen","doi":"10.1115/GT2018-76967","DOIUrl":"https://doi.org/10.1115/GT2018-76967","url":null,"abstract":"Centrifugal compressors are used in large water-cooled chillers for Heating, Ventilating, and Air Conditioning (HVAC) applications. A water-cooled chiller is one of the largest power consumers in a building HVAC system. One way of reducing the power consumption is to use an economizer cycle. In a typical economizer cycle, the vapor from the economizer (located between the condenser and the evaporator) is injected into the inlet of the compressor second stage of a multistage machine. The added cost and complexity of a two-stage compressor can be reduced with a single-stage design. To achieve the best of a single-stage design along with the benefit of an economizer cycle, a novel single-stage compressor with an economizer gas injection into the stage is analyzed using computational fluid dynamics methods. The compressor is designed with an unshrouded impeller and a pipe diffuser. Design parameters such as injection location, angle and size were analyzed to maximize the cycle benefit and achieve a minimum loss in compressor efficiency. Experiments were carried out in a real gas test rig using R134a refrigerant to validate the analytical results. This paper presents the concept and computational results of the parametric study, along with the test rig details and results.","PeriodicalId":388234,"journal":{"name":"Volume 2B: Turbomachinery","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129991690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Zubanov, A. Volkov, V. Matveev, G. Popov, O. Baturin
The article describes a refining method for a fuel pump of rocket powerful turbo-pump unit by the joint usage of mathematical optimization software IOSO, meshing complex NUMECA and CFD complex ANSYS CFX. The optimization software was used for automatic change of the geometry of low-pressure impeller, transition duct and high-pressure impeller to find the optimal design. It was mandatory to keep the original variant of the remaining parts of the pump. For this reason, only geometrical parameters of the blades were varied without changing the contours of the pump meridional flow part. The investigated pump consists of five parts: inlet duct, low-pressure screw centrifugal stage, transition duct, high-pressure screw centrifugal stage and volute outlet duct. The pump main parameters with water as the working fluid (based on experiment data) were the following: high-pressure stage rotor speed was 13300 rpm; low-pressure rotor speed was 3617 rpm by gearbox; inlet total pressure was 0.4 MPa; outlet mass flow was 132.6 kg/s at the nominal mode. Creation of vane unit mesh (rotors and stator transition duct) was performed using NUMECA AutoGrid5. Sector models were used for the calculation simplification. The flow around only one blade or screw was considered. Setting up and solution of the task were carried out in the ANSYS CFX solver. Comparison of calculated characteristics of the basic pump with the experimental data was performed before the optimization. The analysis of characteristics for the obtained optimized pump geometry was carried out. It was found that pump with optimized geometry has greater efficiency in comparison with the original pump variant. The obtained reserve can be used to boost the rocket engine, and/or to reduce the loading of the main turbine, which operates in aggressive oxidizing environment.
{"title":"Optimization of Fuel Two-Stage Screw Centrifugal Pump of Rocket Powerful Turbopump Unit","authors":"V. Zubanov, A. Volkov, V. Matveev, G. Popov, O. Baturin","doi":"10.1115/GT2018-76400","DOIUrl":"https://doi.org/10.1115/GT2018-76400","url":null,"abstract":"The article describes a refining method for a fuel pump of rocket powerful turbo-pump unit by the joint usage of mathematical optimization software IOSO, meshing complex NUMECA and CFD complex ANSYS CFX. The optimization software was used for automatic change of the geometry of low-pressure impeller, transition duct and high-pressure impeller to find the optimal design. It was mandatory to keep the original variant of the remaining parts of the pump. For this reason, only geometrical parameters of the blades were varied without changing the contours of the pump meridional flow part.\u0000 The investigated pump consists of five parts: inlet duct, low-pressure screw centrifugal stage, transition duct, high-pressure screw centrifugal stage and volute outlet duct. The pump main parameters with water as the working fluid (based on experiment data) were the following: high-pressure stage rotor speed was 13300 rpm; low-pressure rotor speed was 3617 rpm by gearbox; inlet total pressure was 0.4 MPa; outlet mass flow was 132.6 kg/s at the nominal mode.\u0000 Creation of vane unit mesh (rotors and stator transition duct) was performed using NUMECA AutoGrid5. Sector models were used for the calculation simplification. The flow around only one blade or screw was considered. Setting up and solution of the task were carried out in the ANSYS CFX solver. Comparison of calculated characteristics of the basic pump with the experimental data was performed before the optimization.\u0000 The analysis of characteristics for the obtained optimized pump geometry was carried out. It was found that pump with optimized geometry has greater efficiency in comparison with the original pump variant. The obtained reserve can be used to boost the rocket engine, and/or to reduce the loading of the main turbine, which operates in aggressive oxidizing environment.","PeriodicalId":388234,"journal":{"name":"Volume 2B: Turbomachinery","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129928238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alberto Greco, V. Michelassi, S. Francini, D. D. Benedetto, Mahendran Manoharan
Gas turbines engine designers are leaning towards aircraft engine architectures due to their footprint, weight, and performance advantages. Such engines need some modifications to both the combustion system, to comply with emission limits, and turbine rotational speed. Aero derivative engines maintain the same legacy aircraft engine architecture, and replace the fan and booster with higher speed compressor booster driven by a single stage intermediate turbine. A multistage free power turbine (FPT) sits on a separate shaft to drive compressors for Liquefied Natural Gas (LNG) applications or generators. The intermediate power turbine (IPT) design is important for the engine performance as it drives the booster compressor and sets the inlet boundary conditions to the downstream power turbine. This paper describes the experience of Baker Hughes, a GE company (BHGE) in the design of the intermediate turbine that sits in between a GE legacy aircraft engine core exhaust and the downstream power turbine. This paper focuses on the flow path of the TCF/intermediate turbine and the associated design, as well as on the 3D steady and unsteady CFD assisted design of the IPT stage to control secondary flows in presence of through flow curvature induced by the upstream TCF.
{"title":"Aero Derivative Mechanical Drive Gas Turbines: The Design of Intermediate Pressure Turbines","authors":"Alberto Greco, V. Michelassi, S. Francini, D. D. Benedetto, Mahendran Manoharan","doi":"10.1115/GT2018-76036","DOIUrl":"https://doi.org/10.1115/GT2018-76036","url":null,"abstract":"Gas turbines engine designers are leaning towards aircraft engine architectures due to their footprint, weight, and performance advantages. Such engines need some modifications to both the combustion system, to comply with emission limits, and turbine rotational speed. Aero derivative engines maintain the same legacy aircraft engine architecture, and replace the fan and booster with higher speed compressor booster driven by a single stage intermediate turbine. A multistage free power turbine (FPT) sits on a separate shaft to drive compressors for Liquefied Natural Gas (LNG) applications or generators. The intermediate power turbine (IPT) design is important for the engine performance as it drives the booster compressor and sets the inlet boundary conditions to the downstream power turbine. This paper describes the experience of Baker Hughes, a GE company (BHGE) in the design of the intermediate turbine that sits in between a GE legacy aircraft engine core exhaust and the downstream power turbine. This paper focuses on the flow path of the TCF/intermediate turbine and the associated design, as well as on the 3D steady and unsteady CFD assisted design of the IPT stage to control secondary flows in presence of through flow curvature induced by the upstream TCF.","PeriodicalId":388234,"journal":{"name":"Volume 2B: Turbomachinery","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130482897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A transonic centrifugal compressor impeller is generally composed of the main and the splitter blades which are different in chord length. As a result, the tip leakage flows from the main and the splitter blades interact with each other and then complicate the flow field in the compressor. In this study, in order to clarify the individual influences of these leakage flows on the flow field in the transonic centrifugal compressor stage at near-choke to near-stall condition, the flows in the compressor at four conditions prescribed by the presence and the absence of the tip clearances were analyzed numerically. The computed results clarified the following noticeable phenomena. The tip clearance of the main blade induces the tip leakage vortex from the leading edge of the main blade. This vortex decreases the blade loading of the main blade to the negative value by the increase of the flow acceleration along the suction surface of the splitter blade, and consequently induces the tip leakage vortex caused by the negative blade loading of the main blade at any operating points. These phenomena decline the impeller efficiency. On the other hand, the tip clearance of the splitter blade decreases the afore mentioned acceleration by the formation of the tip leakage vortex from the leading edge of the splitter blade and the decrease of the incidence angle for the splitter blade caused by the suction of the flow into the tip clearance. These phenomena reduce the loss generated by the negative blade loading of the main blade and consequently reduce the decline of the impeller efficiency. Moreover, the tip clearances enlarge the flow separation around the diffuser inlet and then decline the diffuser performance independently of the operating points.
{"title":"Influences of Tip Leakage Flows Discharged From Main and Splitter Blades on Flow Field in Transonic Centrifugal Compressor Stage","authors":"Masanao Kaneko, H. Tsujita","doi":"10.1115/GT2018-75345","DOIUrl":"https://doi.org/10.1115/GT2018-75345","url":null,"abstract":"A transonic centrifugal compressor impeller is generally composed of the main and the splitter blades which are different in chord length. As a result, the tip leakage flows from the main and the splitter blades interact with each other and then complicate the flow field in the compressor. In this study, in order to clarify the individual influences of these leakage flows on the flow field in the transonic centrifugal compressor stage at near-choke to near-stall condition, the flows in the compressor at four conditions prescribed by the presence and the absence of the tip clearances were analyzed numerically. The computed results clarified the following noticeable phenomena. The tip clearance of the main blade induces the tip leakage vortex from the leading edge of the main blade. This vortex decreases the blade loading of the main blade to the negative value by the increase of the flow acceleration along the suction surface of the splitter blade, and consequently induces the tip leakage vortex caused by the negative blade loading of the main blade at any operating points. These phenomena decline the impeller efficiency. On the other hand, the tip clearance of the splitter blade decreases the afore mentioned acceleration by the formation of the tip leakage vortex from the leading edge of the splitter blade and the decrease of the incidence angle for the splitter blade caused by the suction of the flow into the tip clearance. These phenomena reduce the loss generated by the negative blade loading of the main blade and consequently reduce the decline of the impeller efficiency. Moreover, the tip clearances enlarge the flow separation around the diffuser inlet and then decline the diffuser performance independently of the operating points.","PeriodicalId":388234,"journal":{"name":"Volume 2B: Turbomachinery","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127579432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents results of a detailed investigation of turbine tip-leakage flows at high Mach numbers. The experimental work was carried out using a small blow-down wind tunnel. An idealized blade test section was used to study blade tip-clearance effects in transonic conditions. Unshrouded blade tips are considered and different tip gap heights are investigated. A high blade exit Mach number of Me = 2 was selected deliberately. While conventional transonic turbine stages generally operate at lower supersonic exit Mach numbers, the conditions are representative for ORC turbines. Both experimental and numerical results are presented in this contribution. The results indicate, that tip leakage flow under transonic conditions leads to a complex three-dimensional flow field. A strong interaction between tip gap vortex and trailing edge shocks was observed, that also had a profound effect on the base region. While no final statement on losses could be made in the present configuration, the results indicate a weakened shock system.
{"title":"An Experimental and Numerical Study of Tip-Leakage Flows in an Idealized Turbine Tip Gap at High Mach Numbers","authors":"Maximilian Passmann, S. Wiesche, F. Joos","doi":"10.1115/GT2018-76366","DOIUrl":"https://doi.org/10.1115/GT2018-76366","url":null,"abstract":"This paper presents results of a detailed investigation of turbine tip-leakage flows at high Mach numbers. The experimental work was carried out using a small blow-down wind tunnel. An idealized blade test section was used to study blade tip-clearance effects in transonic conditions. Unshrouded blade tips are considered and different tip gap heights are investigated. A high blade exit Mach number of Me = 2 was selected deliberately. While conventional transonic turbine stages generally operate at lower supersonic exit Mach numbers, the conditions are representative for ORC turbines. Both experimental and numerical results are presented in this contribution. The results indicate, that tip leakage flow under transonic conditions leads to a complex three-dimensional flow field. A strong interaction between tip gap vortex and trailing edge shocks was observed, that also had a profound effect on the base region. While no final statement on losses could be made in the present configuration, the results indicate a weakened shock system.","PeriodicalId":388234,"journal":{"name":"Volume 2B: Turbomachinery","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122240505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Luiz Henrique Lindquist Whitacker, J. T. Tomita, C. Bringhenti
Boosters are commonly used in liquid propellant rocket engines (LPRE) to allow lower propellant pressures in their storage tanks and, thus, smaller structural masses, contributing to cavitation free operation in the subsequent main turbopumps (TP). Boosters can be identified as key components for the overall performance of large engines, and if their operating requirements are stringent, they can operate under cavitation. Thus, effective design and performance tools are fundamental to design the components of these boosters considering this phenomenon. The simulation techniques based on turbulent and multiphase 3-D Computational Fluid Dynamics (CFD) were used in this work at steady state regime. The simulations were done using the commercial software CFX from ANSYS® Workbench. The study was conducted analyzing the performance of the first stage of the hydraulic axial turbine of the liquid oxygen (LOX) booster of the Space Shuttle Main Engine (SSME), at various operation points under cavitation, considering 3.0% tip clearance relative to blade height. The results obtained for, the performance parameters of this stage were compared with those obtained through monophase simulation, and the multiphase technique showed results closer to the experimental ones around the design point (DP), with increased simulation times acceptable for the computational resources currently available. Moreover, the results from the current work show the importance of considering the effects of cavitation through multiphase flow in hydraulic turbines.
{"title":"Turbopump Booster Turbine Performance: Comparison Between Monophase and Multiphase Flows Using CFD","authors":"Luiz Henrique Lindquist Whitacker, J. T. Tomita, C. Bringhenti","doi":"10.1115/GT2018-76879","DOIUrl":"https://doi.org/10.1115/GT2018-76879","url":null,"abstract":"Boosters are commonly used in liquid propellant rocket engines (LPRE) to allow lower propellant pressures in their storage tanks and, thus, smaller structural masses, contributing to cavitation free operation in the subsequent main turbopumps (TP). Boosters can be identified as key components for the overall performance of large engines, and if their operating requirements are stringent, they can operate under cavitation. Thus, effective design and performance tools are fundamental to design the components of these boosters considering this phenomenon. The simulation techniques based on turbulent and multiphase 3-D Computational Fluid Dynamics (CFD) were used in this work at steady state regime. The simulations were done using the commercial software CFX from ANSYS® Workbench. The study was conducted analyzing the performance of the first stage of the hydraulic axial turbine of the liquid oxygen (LOX) booster of the Space Shuttle Main Engine (SSME), at various operation points under cavitation, considering 3.0% tip clearance relative to blade height. The results obtained for, the performance parameters of this stage were compared with those obtained through monophase simulation, and the multiphase technique showed results closer to the experimental ones around the design point (DP), with increased simulation times acceptable for the computational resources currently available. Moreover, the results from the current work show the importance of considering the effects of cavitation through multiphase flow in hydraulic turbines.","PeriodicalId":388234,"journal":{"name":"Volume 2B: Turbomachinery","volume":"353 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122849979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The use of twin scroll volutes in radial turbine for turbocharging applications has several advantages over single passage volute related to the engine matching and to the overall compactness. Twin scroll volutes are of increasing interest in power unit development but the open scientific literature on their performance and modelling is still quite limited. In the present work the performance of a twin scroll volute for a turbocharger radial turbine are investigated in some detail in a wide range of operating conditions at both full and partial admission. A CFD model for the volute have been developed and preliminary validated against experimental data available for the radial turbine. Then the numerical model has been used to generate the database of solutions that have been investigated and used to extract the performance. Different parameters and indices are introduced to describe the volute aerodynamic performance in the wide range of operating conditions chosen. The above parameters can be used for volute development or matching with a given rotor or efficiently implemented in automatic design optimization strategies.
{"title":"Performance Characterization of a Twin Scroll Volute for Turbocharging Applications","authors":"C. Cravero, M. Rocca, A. Ottonello","doi":"10.1115/GT2018-75522","DOIUrl":"https://doi.org/10.1115/GT2018-75522","url":null,"abstract":"The use of twin scroll volutes in radial turbine for turbocharging applications has several advantages over single passage volute related to the engine matching and to the overall compactness. Twin scroll volutes are of increasing interest in power unit development but the open scientific literature on their performance and modelling is still quite limited. In the present work the performance of a twin scroll volute for a turbocharger radial turbine are investigated in some detail in a wide range of operating conditions at both full and partial admission. A CFD model for the volute have been developed and preliminary validated against experimental data available for the radial turbine. Then the numerical model has been used to generate the database of solutions that have been investigated and used to extract the performance. Different parameters and indices are introduced to describe the volute aerodynamic performance in the wide range of operating conditions chosen. The above parameters can be used for volute development or matching with a given rotor or efficiently implemented in automatic design optimization strategies.","PeriodicalId":388234,"journal":{"name":"Volume 2B: Turbomachinery","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123850635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Separated boundary layers of the low pressure turbine blade suction surface under wall heat transfer and pressure gradient conditions are investigated using large eddy simulations (LES) in this paper. The study constructed a converging-diverging channel with a flat plate as the bottom wall, and the pressure distribution of the bottom wall is similar to that of a high lift low pressure turbine blade suction surface. The boundary layer was investigated under different heat transfer boundary conditions of the bottom wall (i.e., the adiabatic wall and the isothermal wall with the wall temperature being 0.8 times of the inflow temperature). The time-averaged flow parameters and the separation bubble characteristics were analyzed and discussed. The evolution of coherent structure diagrams of the boundary layer was also obtained to study the evolution process of the vortex. The results show that the cooled isothermal wall condition can significantly suppress the separation bubble and reduce the frequency of the large scale spanwise vortex roll-up. Under the two wall heat transfer conditions, the scale of the near wall small scale spanwise vortex is similar as well as the scale of the large scale spanwise wortex. The location of the vortex are also approximate under the two wall heat transfer conditions, but the position of the large scale spanwise vortex shedding from separated laminar boundary layers moves upstream under the cooled isothermal wall condition, and the transition process is more rapid than that of the adiabatic wall condition.
{"title":"Large Eddy Simulations of Separated Boundary Layer With Pressure Gradient and Heat Transfer","authors":"Yifei Wu, Weihao Zhang, Z. Zou, Jiang Chen","doi":"10.1115/GT2018-76338","DOIUrl":"https://doi.org/10.1115/GT2018-76338","url":null,"abstract":"Separated boundary layers of the low pressure turbine blade suction surface under wall heat transfer and pressure gradient conditions are investigated using large eddy simulations (LES) in this paper. The study constructed a converging-diverging channel with a flat plate as the bottom wall, and the pressure distribution of the bottom wall is similar to that of a high lift low pressure turbine blade suction surface. The boundary layer was investigated under different heat transfer boundary conditions of the bottom wall (i.e., the adiabatic wall and the isothermal wall with the wall temperature being 0.8 times of the inflow temperature). The time-averaged flow parameters and the separation bubble characteristics were analyzed and discussed. The evolution of coherent structure diagrams of the boundary layer was also obtained to study the evolution process of the vortex. The results show that the cooled isothermal wall condition can significantly suppress the separation bubble and reduce the frequency of the large scale spanwise vortex roll-up. Under the two wall heat transfer conditions, the scale of the near wall small scale spanwise vortex is similar as well as the scale of the large scale spanwise wortex. The location of the vortex are also approximate under the two wall heat transfer conditions, but the position of the large scale spanwise vortex shedding from separated laminar boundary layers moves upstream under the cooled isothermal wall condition, and the transition process is more rapid than that of the adiabatic wall condition.","PeriodicalId":388234,"journal":{"name":"Volume 2B: Turbomachinery","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128494428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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