Experimental investigation on characteristic of rotating stall in a low-speed axial compressor

The full flow characteristic of a 2-stage low-speed axial compressor was investigated with uniform inlet flow.The emphasis of this work was put on the characteristic of rotating stall at different flow coefficient and the stall inception.The results indicate that the modal wave will appear before stall about 30 rotor revolutions,and the rotary speed of modal wave is about 40% rotor speed.The modal wave can be detected across the compressor.The second stage comes into rotating stall first under the effects of the disturbance of the modal wave.The rotary speed of the early stall cell is about 83.3% rotor speed,and the speed will decrease as the stall cell spreads to the first stage,at last about 41.9% rotor speed.As the flow coefficient reduces,the frequency of the stall cell will decrease,and the scope of the stall cell will extend accordingly.