Effect of axially non-uniform rotor tip clearance on the performance of a high speed axial flow compressor stage

An axially nonuniform type of rotor tip clearance was conceived and tried on a single stage compressor. This concept is based on the advantages of a smaller tip clearance in the front portion of the blade and a larger clearance in the rear portion, which allows a higher tip leakage flow to interact with the passage secondary flow, casing wall boundary layer, separated flow on the blade suction surface and the scraping vortex, which are more prominent at the rear portion of the blade. Experimental results indicate that an axially nonuniform clearance can provide improved performance of a compressor stage. Providing the tip clearance in the compressor casing instead of at the blade tip indicates certain advantages. An optimum value of rotor tip clearance was noticed for this compressor stage, both for axially uniform and axially nonuniform clearance