Influence of Reynolds Number on the Unsteady Aerodynamics of Integrated Aggressive Intermediate Turbine Duct
|
摘要
The ultra-high bypass ratio turbofan engine attracts more and more attention in modern commercial engine due to advantages of high efficiency and low Specific Fuel Consumption(SFC). One of the characteristics of ultra-high bypass ratio turbofan is the intermediate turbine duct which guides the flow leaving high pressure turbine(HPT) to low pressure turbine(LPT) at a larger diameter, and this kind of design will lead to aggressive intermediate turbine duct(AITD) design concept. Thus, it is important to design the AITD without any severe loss. From the unsteady flow's point of view, in actual operating conditions, the incoming wake generated by HPT is unsteady which will take influence on boundary layer's transition within the ITD and LPT. In this paper, the three-dimensional unsteady aerodynamics of an AITD taken from a real engine is studied. The results of fully unsteady three-dimensional numerical simulations, performed with ANSYS-CFX(RANS simulation with transitional model), are critically evaluated against experimental data. After validation of the numerical model, the physical mechanisms inside the flow channel are analyzed, with an aim to quantify the sensitivities of different Reynolds number effect on both the ITD and LPT nozzle. Some general physical mechanisms can be recognized in the unsteady environment. It is recognized that wake characteristics plays a crucial role on the loss within both the ITD and LPT nozzle section, determining both time-averaged and time-resolved characteristics of the flow field. Meanwhile, particular attention needs to be paid to the unsteady effect on the boundary layer of LPT nozzle's suction side surface.
The ultra-high bypass ratio turbofan engine attracts more and more attention in modern commercial engine due to advantages of high efficiency and low Specific Fuel Consumption(SFC). One of the characteristics of ultra-high bypass ratio turbofan is the intermediate turbine duct which guides the flow leaving high pressure turbine(HPT) to low pressure turbine(LPT) at a larger diameter, and this kind of design will lead to aggressive intermediate turbine duct(AITD) design concept. Thus, it is important to design the AITD without any severe loss. From the unsteady flow's point of view, in actual operating conditions, the incoming wake generated by HPT is unsteady which will take influence on boundary layer's transition within the ITD and LPT. In this paper, the three-dimensional unsteady aerodynamics of an AITD taken from a real engine is studied. The results of fully unsteady three-dimensional numerical simulations, performed with ANSYS-CFX(RANS simulation with transitional model), are critically evaluated against experimental data. After validation of the numerical model, the physical mechanisms inside the flow channel are analyzed, with an aim to quantify the sensitivities of different Reynolds number effect on both the ITD and LPT nozzle. Some general physical mechanisms can be recognized in the unsteady environment. It is recognized that wake characteristics plays a crucial role on the loss within both the ITD and LPT nozzle section, determining both time-averaged and time-resolved characteristics of the flow field. Meanwhile, particular attention needs to be paid to the unsteady effect on the boundary layer of LPT nozzle's suction side surface.
The ultra-high bypass ratio turbofan engine attracts more and more attention in modern commercial engine due to advantages of high efficiency and low Specific Fuel Consumption(SFC). One of the characteristics of ultra-high bypass ratio turbofan is the intermediate turbine duct which guides the flow leaving high pressure turbine(HPT) to low pressure turbine(LPT) at a larger diameter, and this kind of design will lead to aggressive intermediate turbine duct(AITD) design concept. Thus, it is important to design the AITD without any severe loss. From the unsteady flow's point of view, in actual operating conditions, the incoming wake generated by HPT is unsteady which will take influence on boundary layer's transition within the ITD and LPT. In this paper, the three-dimensional unsteady aerodynamics of an AITD taken from a real engine is studied. The results of fully unsteady three-dimensional numerical simulations, performed with ANSYS-CFX(RANS simulation with transitional model), are critically evaluated against experimental data. After validation of the numerical model, the physical mechanisms inside the flow channel are analyzed, with an aim to quantify the sensitivities of different Reynolds number effect on both the ITD and LPT nozzle. Some general physical mechanisms can be recognized in the unsteady environment. It is recognized that wake characteristics plays a crucial role on the loss within both the ITD and LPT nozzle section, determining both time-averaged and time-resolved characteristics of the flow field. Meanwhile, particular attention needs to be paid to the unsteady effect on the boundary layer of LPT nozzle's suction side surface.
引文
[1]Miller R.J.,Moss R.W.,Ainsworth R.W.,Harvey N.W..The development of turbine exit flow in a Swan-Necked Inter-Stage diffuser.Proceedings of ASME Turbo Expo2003,Georgia,USA,GT2003-38174.
[2]Axelsson L.-U.,Johansson T.G..Evaluation of the flow in an intermediate turbine duct at Off-Design conditions,26th International Congress of The Aeronautical Sciences,Anchorage,Alaska,USA,2008.
[3]Axelsson L.-U.,George W.K..Spectral analysis of the flow in an intermediate turbine duct.Proceedings of ASME Turbo Expo 2008,Berlin,Germany,GT2008-51340.
[4]Wallin F.,Osso C.A.,Johansson T.G.Experimental and numerical investigation of an aggressive intermediate turbine duct:Part 1–Flowfield at Design Inlet Conditions.26th AIAA Applied Aerodynamics Conference,Honolulu,Hawaii,2008,AIAA 2008-7055.
[5]Osso C.A.,Wallin F.,Johansson T.G..Experimental and numerical investigation of an aggressive intermediate turbine duct–Part 2:flowfield under Off-Design inlet conditions.26th AIAA Applied Aerodynamics Conference,Honolulu,Hawaii,2008,AIAA 2008-7056.
[6]Marn A.,G?ttlich E.,Cadrecha D.,et.al..Shorten the intermediate turbine duct length by applying an integrated concept.Proceedings of ASME Turbo Expo 2008,Berlin,Germany,2008:1041-1051.
[7]Spataro R.,Santner C.,Lengani D.,et.al..On the flow Eevolution through a LP turbine with Wide-Chord vanes in an S-Shaped channel.Proceedings of ASME Turbo Expo 2012,Copenhagen,Denmark,2012:1011-1020.
[8]Chaluvadi V.S.P.,Kalfas A.I.,Benieghbal M.R.,Hodson H.P.,Denton,J.D..Blade-Row interaction in a highpressure turbine.AIAA J.Propul.Power,2001,17:892–901.
[9]Pullan G.,Denton J.D..Numerical simulation of vortexturbine blade interaction.Proceedings of the 5th European Conference on Turbomachinery,Prague,Czech Republic,2003.
[10]Stieger R.D.,Hodson H.P..The Unsteady Development of a turbulent wake through a downstream low-pressure turbine blade passage.ASME J.Turbomach.,2005,127:388–394.
[11]Hodson H.P.,Howell,R.J..Blade row interactions,transition,and high-lift airfoils in low-pressure turbines.Annu.Rev.Fluid Mech.2005,37:71–98.
[12]Schobeiri M.T.,€Ozt€urk B.,Ashpis D.E..On the physics of the flow separation along a low pressure turbine blade under unsteady flow conditions.Proceedings of ASME Turbo Expo 2003,Georgia,USA,GT2003-38917.
[13]Schobeiri M.T.,€Ozt€urk B..Experimental study of the effect of periodic unsteady wake flow on boundary layer development,separation,and re-attachment along the surface of a low pressure turbine blade.Proceedings of ASME Turbo Expo 2004,Vienna,Austria,GT2004-53929.
[14]Volino R.J..Effect of unsteady wakes on boundary layer separation on a very high lift low pressure turbine airfoil.ASME J,2011,134(1):011011-011011-16.
[15]Davis R.L.,Yao J.X.,Clark J.P.,Stetson G.,Alonso J.J.,Jameson,A.Unsteady interaction between a transonic turbine stage and downstream components.Proceedings of ASME Turbo Expo 2002,Amsterdam,The Netherlands,GT-2002-30364.
[16]G?ttlich E.,Malzacher F.J.,Heitmeir F.J.,Marn A..Adaptation of a transonic test turbine facility for experimental investigation of aggressive intermediate turbine duct flows.AIAA Paper,Munich,Germany,ISABE-2005-1132.
[17]G?ttlichE.,Marn A.,Malzacher F.,Heitmeir F..On flow separation in a super-aggressive intermediate turbine duct.Proceedings 8th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics,Graz,Austria,2009.
[18]Marn A.,G?ttlich E.,Malzacher F.,Heitmeir F.,Santner C..Comparison between the flow through an aggressive and a super-aggressive intermediate turbine duct.ISABE,Montrel,Canada,2009-1259.
[19]Mahallati Ali.Aerodynamics of a low pressure turbine airfoil under steady and periodically unsteady conditions.Ph.D.Thesis,Carleton University,Ottawa,Canada,2004.
[20]Pfeil H.,Herbst R.,Schro¨der T..Investigations of the laminar-turbulent transition of boundary layers disturbed by wakes.ASME J.Eng.Power,1983,105:130–137.
[21]Schlichting H,Gersten K..Boundary layer theory,Springer,Berlin,Germany,2000.
[2]Axelsson L.-U.,Johansson T.G..Evaluation of the flow in an intermediate turbine duct at Off-Design conditions,26th International Congress of The Aeronautical Sciences,Anchorage,Alaska,USA,2008.
[3]Axelsson L.-U.,George W.K..Spectral analysis of the flow in an intermediate turbine duct.Proceedings of ASME Turbo Expo 2008,Berlin,Germany,GT2008-51340.
[4]Wallin F.,Osso C.A.,Johansson T.G.Experimental and numerical investigation of an aggressive intermediate turbine duct:Part 1–Flowfield at Design Inlet Conditions.26th AIAA Applied Aerodynamics Conference,Honolulu,Hawaii,2008,AIAA 2008-7055.
[5]Osso C.A.,Wallin F.,Johansson T.G..Experimental and numerical investigation of an aggressive intermediate turbine duct–Part 2:flowfield under Off-Design inlet conditions.26th AIAA Applied Aerodynamics Conference,Honolulu,Hawaii,2008,AIAA 2008-7056.
[6]Marn A.,G?ttlich E.,Cadrecha D.,et.al..Shorten the intermediate turbine duct length by applying an integrated concept.Proceedings of ASME Turbo Expo 2008,Berlin,Germany,2008:1041-1051.
[7]Spataro R.,Santner C.,Lengani D.,et.al..On the flow Eevolution through a LP turbine with Wide-Chord vanes in an S-Shaped channel.Proceedings of ASME Turbo Expo 2012,Copenhagen,Denmark,2012:1011-1020.
[8]Chaluvadi V.S.P.,Kalfas A.I.,Benieghbal M.R.,Hodson H.P.,Denton,J.D..Blade-Row interaction in a highpressure turbine.AIAA J.Propul.Power,2001,17:892–901.
[9]Pullan G.,Denton J.D..Numerical simulation of vortexturbine blade interaction.Proceedings of the 5th European Conference on Turbomachinery,Prague,Czech Republic,2003.
[10]Stieger R.D.,Hodson H.P..The Unsteady Development of a turbulent wake through a downstream low-pressure turbine blade passage.ASME J.Turbomach.,2005,127:388–394.
[11]Hodson H.P.,Howell,R.J..Blade row interactions,transition,and high-lift airfoils in low-pressure turbines.Annu.Rev.Fluid Mech.2005,37:71–98.
[12]Schobeiri M.T.,€Ozt€urk B.,Ashpis D.E..On the physics of the flow separation along a low pressure turbine blade under unsteady flow conditions.Proceedings of ASME Turbo Expo 2003,Georgia,USA,GT2003-38917.
[13]Schobeiri M.T.,€Ozt€urk B..Experimental study of the effect of periodic unsteady wake flow on boundary layer development,separation,and re-attachment along the surface of a low pressure turbine blade.Proceedings of ASME Turbo Expo 2004,Vienna,Austria,GT2004-53929.
[14]Volino R.J..Effect of unsteady wakes on boundary layer separation on a very high lift low pressure turbine airfoil.ASME J,2011,134(1):011011-011011-16.
[15]Davis R.L.,Yao J.X.,Clark J.P.,Stetson G.,Alonso J.J.,Jameson,A.Unsteady interaction between a transonic turbine stage and downstream components.Proceedings of ASME Turbo Expo 2002,Amsterdam,The Netherlands,GT-2002-30364.
[16]G?ttlich E.,Malzacher F.J.,Heitmeir F.J.,Marn A..Adaptation of a transonic test turbine facility for experimental investigation of aggressive intermediate turbine duct flows.AIAA Paper,Munich,Germany,ISABE-2005-1132.
[17]G?ttlichE.,Marn A.,Malzacher F.,Heitmeir F..On flow separation in a super-aggressive intermediate turbine duct.Proceedings 8th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics,Graz,Austria,2009.
[18]Marn A.,G?ttlich E.,Malzacher F.,Heitmeir F.,Santner C..Comparison between the flow through an aggressive and a super-aggressive intermediate turbine duct.ISABE,Montrel,Canada,2009-1259.
[19]Mahallati Ali.Aerodynamics of a low pressure turbine airfoil under steady and periodically unsteady conditions.Ph.D.Thesis,Carleton University,Ottawa,Canada,2004.
[20]Pfeil H.,Herbst R.,Schro¨der T..Investigations of the laminar-turbulent transition of boundary layers disturbed by wakes.ASME J.Eng.Power,1983,105:130–137.
[21]Schlichting H,Gersten K..Boundary layer theory,Springer,Berlin,Germany,2000.