Analysis of leakage flow and loss in a linear compressor cascade with moving endwall

In order to alleviate the efficiency penalty of the leakage flow, especially for large relative clearance in the rear stage of high-pressure compressors, numerical simulations were carried out to investigate the effect of the moving endwall on a compressor cascade with particular emphasis on revealing the loss mechanisms of large clearances. The flow field, loss characteristics, and entropy generation rate were analyzed. The results show that the boundary layer skew induced by the upstream moving endwall significantly improves the corner separation for the datum case without clearance. For the cases with clearances, the moving endwall not only increases the leakage loss but also enhances the loss sensitivity to the clearance size. The large turn of the streamlines causes the large spanwise gradient of the axial and pitchwise velocity components, which is the major cause of the high loss. Therefore, the leakage loss can be reduced by changing the ∂ Vy/∂ z and ∂ Vx/∂ z terms in the middle and downstream regions of the blade passage.