端壁凹槽控制扩压叶栅角区分离的数值研究

Numerical Study of Corner Separation Control on Compressor Cascade With Endwall Groove

为揭示端壁凹槽控制高速扩压叶栅角区分离、降低叶栅气动损失的物理机制,采用数值方法研究了高速扩压叶栅NACA65-K48附加具有不同轴向位置和横向长度的端壁凹槽时叶栅的流场结构和气动特性。结果表明:叶栅出口总压损失系数最大降低8.08%,静压升约提高0.67%。近端壁气流在凹槽内部诱导出复杂旋涡结构,该旋涡结构反过来为凹槽附近的气流注入了径向动量,促进了低能流体在凹槽附近的径向迁移,减轻了低能流体在角区的堆积。当凹槽位于分离点处且横向宽度较小时,能够在一定程度上降低总压损失;凹槽距前缘0.78弦长、宽度为4mm时可获得最佳控制效果,叶片吸力面螺旋分离点弱化为一小段分离线;随着凹槽位置进一步向尾缘方向移动,凹槽对角区流动的控制能力减弱。

In order to reveal the physical mechanism of endwall groove treatment on controlling the flow separation in corner region and reducing the aerodynamic loss of high-speed compressor cascades,the flow field structure and aerodynamic characteristics of high-speed compressor cascade NACA65-K48 with different axial position and transverse length of endwall grooves were studied by numerical method.The results showed that,a maximum total pressure loss coefficient reduction of 8.08%together with a static pressure coefficient increase of 0.67%were gained.Airflow close to the endwall induced complex vortexes in the groove,which in turn injected radial momentum into the near endwall airflow close to the groove,promoting the radial migration of low-energy fluid close to the groove,reducing the accumulation of low-energy fluid in the corner region.The flow loss could be reduced by a certain extent,while the groove is located at the separation point with a small transverse width.The optimal flow control effect was obtained and the spiral separation point on suction surface weakened into a separation line,when the groove was located at 0.78 chord length from the leading edge with a 4 mm width.As the groove moved further towards the tailing edge,its control ability on corner flow would be weaken.