Experimental investigation of stall margin enhancement using novel casing treatment under the rotating inlet distortion

This paper carries out an experimental investigation of a new type of casing treatment to improve axial flow fan/compressor stall margin. The main work is, simulating the rotating inlet distortion on a low-speed fan, describing the pressure rise curve and efficiency curve under different conditions with the experimental data so as to analyze the compressor's performance under distortion inlet conditions on the fan and study the novel casing treatment's ability of stability enhancement. The experimental results show that when the pressure rise curve moves to the lower-right direction under inlet distortion, the stall margin is significantly decreased under the condition of different distortion degrees; the new type casing treatment has a significant effect on expanding the stability of compressor under the rotating inlet distortion; when the distortion speed is low (200, 500 r/min), the expansion of stabilizing effect is obvious, the stall margin enhancement is about 10% to 20%, and the efficiency loss caused by the casing treatment is small; when the distortion speed is 800 r/min, the enhancement of stability is not obvious, but the efficiency can be increased by 1%-2%; under the higher distortion speed condition, the different rotating directions of the distortion plates result in different effects on stability enhancement; the co-rotation distortion can enhance the stall margin by about 3%-10% with a efficiency increase about 1%; the counter rotation distortion can enhance the stall margin by more than 10%, even to 20% with a efficiency loss about 1%.