FLOW VISUALIZATIONS OF FLOW FIELD IN ENDWALL REGION OF A COMPRESSOR CASCADE

This paper describes flow visualizations of the flow field in the endwall region of a compressor cascade. Within the cascade passage without radial clearance,it was found that many low-energy fluids exit in the corner between the suction surface and the endwall, and some vorticities of the corner vortex come from the leading edge horse shoe vortex.Tangential migration of the pressure-side horse-shoe vortex leads to flow mixing among the endwall boundary layer, suction surface boundary layer and the horse-shoe vortex.Small radial clearance leads to a weak leakage vortex that is far away from the suction surface,while large radial clearance leads to a strong one closer to the suction surface.The corner vortex is not obvious due to blowing of the leakage flow.In the endwall region, reaction among the vortexes and the boundary layers result in much more flow mixing and unsteadiness.