弯曲叶片降低能量损失的涡动力学机制

Reduction of energy loss by bowed blades

采用实验与数值模拟相结合的手段 ,从涡动力学的角度阐述了弯叶片降低能量损失的机理 .研究了在不同攻角、不同出口马赫数、不同弯角条件下涡轮叶栅流场内主要旋涡的生成与发展 ;并通过与直叶栅的对比 ,研究了叶片弯曲对马蹄涡起始分离点位置及对通道涡位置强度的影响 ,从截面涡结构入手 ,分析了叶片弯曲这种边界条件的改变方式对通道涡稳定性的影响 ;通过分析在不同气动条件下通道涡对损失贡献的差异指出了在通道涡强度与尺度较大的叶栅 ,叶片弯曲不但会直接通过改变通道涡的强度 ,减少通道涡本身的损失来影响损失的大小 ,同时也会通过对通道涡位置的改变来影响损失的分布与大小 .

The origination and development of major vortexes in turbine cascade were investigated at different attack angles and outlet mach numbers and bowed angles by combining experiments with numerical simulations. By comparing the difference of flow field in bow and straight blade cascade, the effects of blade bowing on the position of saddle point of horseshoe vortex and on the strength and position of the passage vortex were investigated. The effect of blade bowing on the stability of passage vortex was also studied through the analysis of section topology. By analyzing the difference of the contribution of passage vortex to the energy loss under different aerodynamic conditions, it was pointed out that for a cascade with strong passage vortex, the reduction of energy loss was the result of not only the decrease of passage vortex strength due to blade bowing but also the redistribution of boundary layer.