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