Abstract:

From the analysis of the shape of the end wall boundary layer at the entrance of a rotor blade tip, the discrepancy in the boundary layer, between a linear cascade without end wall motion (denoted here situation No.1) or a linear cascade only with end wall motion (situation No.2) and real circumstances, is pointed out. From the relative motion concept of rotor fixing and stator rotating, the experimental device (situation No.3) for simulating the rotor blade tip clearance flow is designed. In the above three situations, the pressure distribution on the blade surfaces and blade tip leakage flows are measured. The experiments show that the tip leakage vortex in situation No.3 forms earlier and the leakage mass flow rate is larger than in situations No.1 and No.2. The leakage flow calculated using the Rains' model, is satisfactorily agreeable to the experiments over rear part of the blade, but toward the leading edge there is a tendency for the model to overpredict the leakage flow, due to the large streamwise pressure gradient comparable to that across the tip.

Key words: compressor, compressor rotor, tip leakage flow, cascade, end-wall boundary layer