仿生人字形小肋阵列对压气机叶栅角区分离的控制

Control of corner separation for compressor cascade with bio-inspired herringbone riblets

通过数值模拟的方法探究了一种新型被动控制结构——仿生人字形小肋阵列,对压气机叶栅角区分离的控制效果及作用机理。人字形小肋阵列被布置在叶栅前缘端壁处,并探究了肋条高度和偏转角对角区分离控制效果的影响规律。研究表明:人字形小肋阵列在叶栅整个稳定工作范围内均能有效改善角区的流动,高度仅为0.08附面层厚度且偏转角为30°的小肋阵列,最高可以使总压损失降低9.89%,静压系数提升12.27%。流场细节表明:小肋通道内的小尺度涡流可以通过积聚效应,在下游形成紧贴附面层底部的高强度大尺度涡流,相较于传统微型涡流发生器有效降低了附加损失;诱导涡增强了附面层与主流的掺混,抑制端壁附面层内低能流体的横向迁移,进而延缓了分离涡的形成,消除了端壁角区的涡环,有效改善了叶栅角区的流动。

A novel passive control method for bio-inspired herringbone riblets was applied to relieve the flow near the blade endwall in a linear cascade,and its effectiveness and mechanism in controlling corner separation were investigated through numerical simulations.The herringbone riblets were placed at the upstream endwall of the blade,and the influence of riblet height and deflection angle on corner separation control was investigated.The results showed that the herringbone riblets can effectively relieve the flow near the blade endwall over the operating range,and the implementation of herringbone riblets with a height of only 0.08 boundary layer thickness and a deflection angle of 30 degrees can reduce the total pressure loss by up to 9.89% and increase the static pressure coefficient by 12.27%.Flow details indicated that small-scale vortices in the riblet channel can accumulate and form high-intensity large-scale vortices close to the bottom of the boundary layer downstream,which effectively reduced additional losses compared with traditional micro vortex generators.Furthermore,the induced vortices enhanced the mixing of the boundary layer and main flow,inhibited the lateral migration of low-energy fluid in the endwall boundary layer,and delayed the formation of separation vortices,eliminating vortex ring in the corner region and effectively improving the flow near the blade endwall.