Effect of moving end wall on tip leakage flow in a compressor cascade with different clearance heights

Numerical simulations have been carried out to investigate the effect of the moving end wall on the tip leakage flow structure in a compressor cascade with four different tip clearance heights. A detailed comparison of the leakage flow’s loss; mass flow rate; and the tip leakage vortex and its roll-up, trajectory, size, and interaction with the passage flow was made. The results show that the performance of the cascade changes more severely as the tip clearance height increases with the moving end wall than with the stationary end wall. The roll-up of the tip leakage vortex has been studied by analyzing the pathline structure and vorticity distribution. An alternative explanation is proposed for the initial roll-up mechanism of the tip leakage vortex. The vorticity transport is responsible for the initial roll-up of the vortex, whereas the leakage jet/passage flow shearing is responsible for the vortex development. The smaller the clearance height is, the easier it is for the moving end wall to alter the vorticity transport from the gap to the tip leakage vortex.