Study on Circumferential Propagation Characteristics of Self-induced Unsteady Pulsations in Centrifugal Compressors

The self-induced unsteady pulsation characteristics and stability have directly influence on the performance and safety of the compressor. Based on a stage of a centrifugal compressor adopted in a compressed air energy storage system, computational fluid dynamics method was used to obtain unsteady numerical simulation results, and the circumferential propagation characteristics of the self-induced unsteady pulsation were studied and extracted. Results show that within the frequency range of 0.3~0.5 times of the blade passing frequency, the circumferential-scale characteristics of self-induced unsteady pulsation are significant. And as the flow rate increases, the number of modes increases from 15 to 19, while the mode speed decreases from -0.65 times of the blade speed to -0.56 times of the blade speed. The number of modes and speed of the circumferential disturbance group determine the self-induced unsteady pulsation frequency of the blade tip. The key parameters for the circumferential propagation of self-induced unsteady pulsation have been determined, and it has been found that the phase difference of pulsations among different channels is the fundamental cause of circumferential disturbances.