Passive Separation Control with Blade-End Slots in a Highly Loaded Compressor Cascade

The proposed passive control method, blade-end slots, is implemented to reorganize the blade-end flow in a highly loaded compressor cascade under a wide incidence range at Ma=0.59. Both experimental and numerical investigations are conducted to validate the control effect and reveal the control mechanism. Experimental results show that the proposed method can effectively suppress the corner separation and broaden the effective operating range. The total pressure loss in the measurement plane is significantly reduced, ranging as high as 18.4, 20.6, 24.3, and 39.4% under the incidence angle of -1.69 degrees, 0 degrees, 2 degrees and 4 degrees, respectively. Flow details indicate that the blade-end slots can generate self-adaptive high-momentum jet flows through the pressure difference between blade pressure and suction surface. The self-adaptive jet flow reenergizes the local low-momentum fluid to reduce separation, and restrain its migration toward midspan. The low-momentum flows near the endwall on the pressure side are aspirated, thus weakening the cross-passage migration of low-momentum endwall flow into suction surface corner. Proportion of unseparated regions in the blade midspan is enlarged; consequently, flow capacities are improved. The attachment at the blade-end regions is enhanced, and the insufficient circulation originally found at the blade extremity is improved.