INITIAL DISTURBANCE FORMS OF ROTATING STALL IN AXIAL FLOW COMPRESSOR

The process of rotating stall developing in a single-stage axial-flow compressor was investigated experimentally.By means of eight dynamic pressure transducers equally located circumferentially in the inlet section of the compressor,the dynamic pressure signals of the rotating stall developing process were measured.The data have been analyzed with the SFC (Spatial Fourier Coefficient) method and the variation of the circumferential phase of initial disturbance signals with time have been obtained.So,it was found that there are two initial disturbance forms of rotating stall,rotating waves and small stall cells.In order to study the factors influencing the initial disturbance forms,the compressor was tested under 55 conditions combining four types of compressor configuration,two solidities of rotor,three rotation speeds,different IGV outlet angles .According to the experimental results,the initial disturbance form of single-stage compressor without IGV was rotating waves.For the isolated rotor without IGV,the forms were rotating waves at high rotor speeds,and small stall cells at low rotor speed.For the compressor with IGV,negative prewhirl angles of IGV enhanced the rotating waves,and increased the pretelling time of stall.Decreasing the solidity of rotor almost did not affect the form of stall initial disturbance.