Hub clearance effects of a cantilevered tandem stator on the performance and flow behaviors in a small-scale axial flow compressor

Abstract

The impacts of the increased hub clearance size (HCS) in the cantilevered tandem stator on the overall performance and flow behaviors have been investigated based on numerical simulations in a small-scale axial flow compressor stage. The results indicate that the HCS variation in the front blade of the tandem stator has a more significant effect on the compressor peak efficiency and stall margin. However, there is no obvious change of the compressor performance with the increase of the HCS in the rear blade. Detailed flow analysis shows that the increase of the HCS in the front blade has remarkable impacts on the flow fields in the front blade, while it has an only slight influence on the hub flow fields in the rear blade. It is found that the compressor efficiency penalty is due to the increase of the loss generation near the hub caused by the larger extent of hub leakage flow, while the stall margin improvement is due to the redistribution of the mass flow rate along the spanwise direction. As a result, the inlet flow condition within the upper blade span is improved and the flow blockage is reduced. The resulting influence of the increased HCS in the rear blade is mainly located near the blade leading edge of the rear blade, and there is no remarkable effect on the flow field in the front blade passage.