Experimental study of the impact of hole-type suction on the flow characteristics in a high-load compressor cascade with a clearance

In a low-speed linear cascade wind tunnel, effects of boundary layer suction on the flow characteristic in a highly-loaded compressor cascade with a stator clearance are studied experimentally, and two types of clearance including "long clearance" and "short clearance" are considered separately. In particular, hole-type suctions with different locations and distributions on the endwall are applied to control clearance flow and loss. The nature of flow separation is described by analyzing the properties of the limiting streamlines, based on the ink-trace flow visualizations on the cascade surface and lower endwall. The configuration of suction holes was associated with the kinetic energy of a clearance flow and the interaction of tip clearance flow with the endwall boundary layer and the suction surface boundary layer. The separation line and reattachment line form the base of a separation structure for corners with clearance. The results show that the clearance flow can be greatly improved and the losses reduced to some extent when boundary layer suction is adopted appropriately. The maximum amplitude of the loss reduction in different schemes with clearance is 32%.