THREE-DIMENSIONAL FLOW FIELD INSIDE A COMPRESSOR ROTOR TIP REGION

An experimental study of the three-dimensional flow field inside the tip region of a low-speed,large-scale axial-flow compressor rotor has been completed.With the help of a rotating four-coordinate probe traverse mechanism,the measurements were conducted with a five-hole conical probe in both design condition and near stall condition.The results indicate that the tip leakage vortex plays a decisive role in the tip region flow in the design condition,leading to substantial flow loss and blockage in the passage.In near stall condition,flow separation occurs on the blade suction surface while radial migration of the boundary layer on the suction surface is strong,which makes more low-energy fluid accumulate at the corner between the casing annual wall and the suction surface.A corner vortex is induced by the tip leakage flow, and the low-energy fluid migrates to the pressure side due to the effect of the leakage vortex.Strong flow mixing among the corner vortex,the leakage vortex,the boundary layer on the casing wall and the main flow occurs at median part of the passage,which leads to substantial deficiencies of relative total pressure and relative velocity.