Experimental and numerical investigation of stepped tip gap effects on an axial-flow compressor

The effects stepped tip gaps on the performance and flow field of a subsonic axial flow compressor rotor were experimentally and numerical investigated. Three different casing configurations were designed and tested on a subsonic axial compressor. Experiments were taken under both 5059 r/min and 8013 r/min conversion speeds. The experimental results showed that the inclusion of stepped tip gaps gave increased pressure ratio, efficiency, and stall margin throughout the mass flow range at both speeds if compared with the baseline case with design tip clearance level. Numerical simulation was performed for the compressor rotor with stepped tip gaps to uncover the complexities of stepped tip gaps flow phenomena.