Effects of holes-type suction on performance in a high-load compressor with a clearance

The effects of endwall-hole-type boundary layer suction on the airfoil flow characteristic and aerodynamic performance in a highly loaded compressor linear cascade with a clearance was studied experimentally. Through a comparative analysis of three different suction schemes and the prototype scheme, the mechanism of boundary layer suction inhibiting the clearance flow, reducing the loss was discussed. The ink-trace flow visualization on the airfoil surface and the lower end-wall was carried out and the parameters at outlet were measured by a five-hole probe to comparatively analyze a distribution of the loss and the flow characteristics. The results show that the suction can effectively reduce the kinetic energy of the clearance flow so as to reduce the blending effect between the clearance flow and the main stream and weaken the flow separation induced by clearance on end-wall when suction holes are arranged in the clearance. Thus, three-dimensional flow separation can be controlled effectively and the loss decreases a lot with a maximum reduction of 16.7%. The flow separation and the loss induced by clearance flow are dominated in the flow path. Although the suction could effectively suppress the development of boundary layer and secondary flow on end-wall when suction holes are arranged along pitch-wise, the local effect may not significantly affect the overall performance of the cascade. To some extent, the unreasonable layout of suction holes may have a negative influence on the mainstream, leading to a rising total loss. It is worth noting that the loss in scheme 4 increases by 3% approximately.