Endwall boundary layer separation in a single-stage axial-flow low-speed compressor and a high-stagger compressor cascade

The paper describes an investigation of the overtip endwall flow in a single-stage axial-flow low-speed compressor (absolute flow) and in a corresponding compressor cascade (simulated relative flow) with a tip clearance on one side. The clearance to chord ratio is 3% in both cases. Oil flow pictures of the rotor casingwall and cascade endwall are used to visualize and analyse the boundary layers on the walls at various flow rates and corresponding inlet angles, respectively. The results enable the different sources of endwall blockage to be identified and changes with flow rate or inlet angle to be determined.