Experimental study on unsteady wake impacting effect in axial-flow compressors

In the present study, the specific wake impacting effect (WIE) in compressors was used to control unsteady separated flows inside axial-flow compressors. Time-averaged performances were analyzed, key factors affecting the positive effects of WIE were studied and perspectives of engineering applications were discussed. Experiment results showed that when the compressor was working under near stall conditions, separated flows over rotor blade rows could be remarkably suppressed by utilizing WIE and properly adjusting two important parameters of impacting frequency and impacting intensity (wake defect). Under near stall condition, the flow-field structure inside the compressor was significantly improved and time-averaged performances were boosted, e.g. when over(n, -) = 85 % n₀ the total pressure increment was increased by 5.4%, the efficiency of the compressor was increased by 5.5% and the stall margin was increased by 30.7% under the condition of optimal impacting frequency and optimal impacting intensity.