振动凸包控制低雷诺数高负荷低压涡轮叶栅层流分离的数值研究
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摘要
为了抑制高载荷低压涡轮PAKB叶栅在低雷诺数2.5×104工况下的层流分离,在叶片吸力面布置振动凸包进行主动流动控制,凸包为半正弦型几何,以最大振幅1mm、频率200Hz垂直于壁面按正弦波形非定常振动,通过非定常数值方法研究了振动凸包位置、几何宽度对叶栅气动性能的影响。结果表明,最佳振动凸包位置位于峰值速度点上游附近,叶栅总压损失系数相较无控叶栅而言降低28.8%,而位于分离点下游以及峰值速度点远上游的振动凸包恶化了叶栅性能;当振动凸包置于吸力面最佳位置时,凸包几何宽度对叶栅损失的影响较小。振动凸包流动控制机理来源于附着于叶片吸力面的连续凸包脱落涡团,涡团通过增加主流与壁面低能流体之间的能量交换,将低能流体限制于壁面附近,有利于抑制大尺度流动分离。
To alleviate the laminar separation on high loaded low pressure turbine cascade of PAKB that operating at low Reynolds number of 2.5×104,a dynamic hump was arranged on the suction surface of the blade for active flow control. The hump,shaped as half sinusoidal,vibrated normal to the blade surface in sine wave,with maximum amplitude of 1 mm and frequency of 200 Hz. The effects of hump location and width on cascade performance were studied through unsteady numerical simulation. The cascade with dynamic hump located upstream and close to the peak velocity point has the lowest total pressure loss coefficient,which is reduced by 28.8% compared with uncontrolled cascade. When the hump is placed downstream of separation point or far upstream of peak velocity point,the cascade performance grows worsen. It is also revealed that the effects of hump width on cascade performance are small when putting the hump at the optimum location. The flow control mechanism of laminar separation comes from the continuous small laminar vortices that are detached from the dynamic hump and attached to the suction surface. Continuous vortices confine the low-energy fluid near the suction surface by energy exchange between the free flow and near-wall flow,which suppress the large-scale flow separation.
To alleviate the laminar separation on high loaded low pressure turbine cascade of PAKB that operating at low Reynolds number of 2.5×104,a dynamic hump was arranged on the suction surface of the blade for active flow control. The hump,shaped as half sinusoidal,vibrated normal to the blade surface in sine wave,with maximum amplitude of 1 mm and frequency of 200 Hz. The effects of hump location and width on cascade performance were studied through unsteady numerical simulation. The cascade with dynamic hump located upstream and close to the peak velocity point has the lowest total pressure loss coefficient,which is reduced by 28.8% compared with uncontrolled cascade. When the hump is placed downstream of separation point or far upstream of peak velocity point,the cascade performance grows worsen. It is also revealed that the effects of hump width on cascade performance are small when putting the hump at the optimum location. The flow control mechanism of laminar separation comes from the continuous small laminar vortices that are detached from the dynamic hump and attached to the suction surface. Continuous vortices confine the low-energy fluid near the suction surface by energy exchange between the free flow and near-wall flow,which suppress the large-scale flow separation.
引文
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[18] Popovic I,Zhu J,Dai W,et al. Aerodynamics of a Family of Three Highly Loaded Low-Pressure Turbine Airfoils:Measured Effects of Reynolds Number and Turbulence Intensity in Steady Flow[R]. ASME GT 2006-91271.
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[20]孙宇涛,任玉新.单级跨音速压气机内流场的非定常模拟及损失分析[J].清华大学学报:自然科学版,2009,5:759-762.
[21] Liu Xiaomin,Zhou Haiyang. Numerical Investigations of Flow Separation Control for a Low Pressure Turbine Blade Using Steady and Pulsed Vortex Generator Jets[R]. ASME GT 2010-22587.
[22] Dhakal T P,Jarnal T,Walters D K. Numerical Simulation of a PAK-B Airfoil Using Fully Turbulent and Transition-Senstive RANS Models[C]. Denver:Proceedings of ASME 2011 International Mechanical Engineering Congress&Exposition,2011.
[2]朱俊强,屈骁,张燕峰,等.高负荷低压涡轮内部非定常流动机理及其控制策略研究进展[J].推进技术,2017,38(10):2186-2199.(ZHU Jun-qiang,QU Xiao,ZHANG Yan-feng,et al. Research Progress on Unsteady Flow Mechanism and Control Strategies of High-Lift Low Pressure Turbine[J]. Journal of Propulsion Technology,2017,38(10):2186-2199.)
[3] Lake J P,King P I,Rivir R B. Low Reynolds Numbers Loss Reduction on Turbine Blades with Dimples and VGrooves[R]. AIAA 2000-0738.
[4]张波,李伟,卢新根,等.变工况下超高负荷低压涡轮叶片边界层被动控制[J].航空动力学报,2012,27(12):2805-2813.
[5] Volino R J. Passive Flow Control on Low-Pressure Turbine Airfoils[R]. ASME GT 2003-38728.
[6] Bons J P,Sondergaard R,Rivir R B. Turbine Separation Control Using Pulsed Vortex Generator Jets[J].Journal of Turbomachinery,2001,123:198-206.
[7] Bons J P,Sondergaard R,Rivir R B. The Fluid Dynamics of LPT Blade Separation Control Using Pulsed Jets[J]. Journal of Turbomachinery,2002,124:77–85.
[8] Volino R J. Separation Control on Low-Pressure Turbine Airfoils Using Synthetic Vortex Generator Jets[R].ASME GT 2003-38729.
[9]伊进宝,乔渭阳,孙大伟.低压涡轮叶栅流动分离主动控制实验研究[J].航空动力学报,2007,22(5):1055-1061.
[10] Volino R J,Kartuzova O,Ibrahim M B. Experimental and Computational Investigations of Low-Pressure Turbine Separation Control Using Vortex Generator Jets[R].ASME GT 2009-59983.
[11] Volino R J,Kartuzova O,Ibrahim M B. Separation Con-trol on a Very High Lift Low Pressure Turbine Airfoil Using Pulsed Vortex Generator Jets[R]. ASME GT 2010-23567.
[12] Rizzetta D P,Visbal M R. Plasma-Based Flow-Control Strategies for Transitional Highly Loaded Low-Pressure Turbines[J]. Journal of Fluids Engineering,2007,130(4).
[13] Marks C,Sondergaard R,Wolff M,et al. Experimental Comparison of DBD Plasma Actuators for Low Reynolds Number Separation Control[R]. ASME GT 2011-45397.
[14] Sinha S K,Wang Heng. Improving the Efficacy of an Active Flexible Wall for Controlling Flow Separation[R]. AIAA 99-0923.
[15] Weddle A,Zaremski S,Zhang Lucy,et al. Control of Laminar Separation Bubble Using Electro-Active Polymers[R]. AIAA 2012-2682.
[16] Gall P D. A Numerical and Experimental Study of the Effects of Dynamic Roughness on Laminar Leading Edge Separation[D]. West Virginia:West Virginia University,2010.
[17]张波,李伟,黄恩量,等.超高负荷低压涡轮叶型边界层被动控制[J].推进技术,2012,33(5):747-753.(ZHANG Bo,LI Wei,HUANG En-liang,et al,Boundary Layer Passive Control of an Ultra-HighLift Low-Pressure Turbine Blade[J]. Journal of Propulsion Technology,2012,33(5):747-753.)
[18] Popovic I,Zhu J,Dai W,et al. Aerodynamics of a Family of Three Highly Loaded Low-Pressure Turbine Airfoils:Measured Effects of Reynolds Number and Turbulence Intensity in Steady Flow[R]. ASME GT 2006-91271.
[19] Shyne R J. Experimental Study of Boundary Layer Behavior in a Simulated Low Pressure Turbine[R]. NASA TM-1998-208503.
[20]孙宇涛,任玉新.单级跨音速压气机内流场的非定常模拟及损失分析[J].清华大学学报:自然科学版,2009,5:759-762.
[21] Liu Xiaomin,Zhou Haiyang. Numerical Investigations of Flow Separation Control for a Low Pressure Turbine Blade Using Steady and Pulsed Vortex Generator Jets[R]. ASME GT 2010-22587.
[22] Dhakal T P,Jarnal T,Walters D K. Numerical Simulation of a PAK-B Airfoil Using Fully Turbulent and Transition-Senstive RANS Models[C]. Denver:Proceedings of ASME 2011 International Mechanical Engineering Congress&Exposition,2011.