被动射流旋涡对高速扩压叶栅气动性能的影响

Effects of Passive Vortex Generator Jet on Aerodynamic Performance of a High-Speed Compressor Cascade

关键词:  被动射流旋涡  高速扩压叶栅  气动性能  总压损失

Key words:  Passive vortex generator jet  High-speed compressor cascade  Aerodynamic performance  Total pressure loss

摘要:

提出了一种利用压力面与吸力面间压差产生射流旋涡的被动流动控制技术以改善压气机叶栅的气动性能，在进口马赫数Ma=0.67的高速扩压叶栅上验证了其有效性。结果表明，射流旋涡可有效增强吸力面附面层与主流间的能量交换，改变下游壁面涡的结构和尺寸，推迟流动分离，减小角区损失。当射流距分离线或端壁较近时，当地较厚的附面层使得旋涡上洗区的掺混损失增加；而射流距分离线或端壁过远时均会减弱下洗区能量注入对角区低能流体的影响；指向端壁的射流会增加壁面涡强度，而沿远离端壁方向过大的偏角则会减弱射流旋涡强度，从而减弱其控制效果。当射流轴向距叶片前缘[xj/cx]=40%、沿叶高距端壁h/H=15%、射流偏角β=60°时，其改善栅内流动的效果最佳，总压损失减小可达5.2%，而射流流量仅相当于主流的0.27‰。

Abstract:

To improve the aerodynamic performance of compressor cascades，a flow control technique using the pressure difference between the pressure surface and the suction surface to generate passive vortex generator jet (PVGJ) is proposed，and the effectiveness of the method is validated on a high-speed compressor cascade at Ma=0.67. Results show that the vortex jet is able to strengthen momentum exchange between the boundary layer and the main flow and to change the structure and size of wall vortex significantly. As a result，the separation line is shifted downstream and the loss is decreased. It is found that jets close to the separation line or the end-wall would increase the mixing losses in the up-washed side of the vortex because of the thick boundary layer in these areas. Besides，an excessive distance between the jet and the end-wall would decrease the effect of momentum transition in the down-washed side on the low energy fluid in the corner region. As for the effect of the skew angle，jets pointing towards the end-wall would strengthen the wall vortex while jets with too large skew angles would reduce the induced vortex，thus weakening the performance of PVGJ on the loss reduction. The optimum jet location is around 40% axial chord length and 15% blade height with a skew angle of 60°. The maximum total pressure loss reduction is up to 5.2%，whereas the jet-to-inflow mass flow rate is only 0.27‰.