According to analysis of the characteristics of frequency and propagation of the sound generated by the rotating stall

an acoustic measuring method is developed

in which the characteristic parameters

such as the number and propagation speed of stall cells

are measured.Compared with existing methods

this method is a untouched measurement so as to avoid not disturb ance of the flow field.The primary experimental results obtained on a transonic axial-flow compressor facility demostrate the feasibility of this method.