叶片尾缘冷气喷射气动与传热性能分析

Analysis of Aerodynamic and Heat Transfer Performance of the Blade Trailing Edge Ejection

基于尺度自适应（Scale Adaptive Simulation,SAS）湍流模型,对叶片尾缘偏开缝射流尾迹结构、尾迹掺混损失和壁面冷却有效度在不同射流/主流速度比（VR）条件下的变化规律进行数值模拟研究。结果表明：VR为1.0时冷气对尾缘壁面的冷却效果总体较好;上、下板尾缘脱落涡的主导结构均为卡门涡,随着VR的增大,其脱落频率与旋涡强度增大,导致涡量和剪切应力升高,而尾迹掺混损失由湍流脉动能量和板后回流区长度共同决定;VR为0.5和1.0时尾迹掺混损失相差不大,VR为1.5时相比0.5时增大了4.53%。

The effect of trailing edge coolant ejection on the film-cooling effectiveness,mixing loss and wake flow characteristics of the subsonic turbine blade was numerically studied.The Scale Adaptive Simulation（SAS） turbulence model was selected to solve the unsteady RANS equation.The three different velocity ratios（VR） ranging from 0.5 to 1.5 were chosen to analyze the effect of coolant ejection on the aerodynamic and heat transfer performance.Results showed that the film-cooling effectiveness is generally higher than other cases when VR is 1.0.The mixing loss coefficient is basically same when VR is 0.5 and1.0,but increases significantly at VR of 1.5.The mixing loss in the wake depends on both the turbulent fluctuation energy and the recirculation zone length in flow direction.The main structures of shedding vortex behind upper and lower plates are Karman vortex.The frequency and amplitude of shedding vortex constantly increase with VR,leading to increased vorticity and shear stress.