Frequency-domain analysis of unsteady flow in multi-stage transonic compressor

Three-dimensional unsteady solver has been developed based on three-dimensional Denton steady solver. Steady and unsteady numerical simulation have been conducted on multi-stage transonic compressor near stall point, and then frequency-domain analysis of unsteady flow field have been conducted on some typical radial sections. Frequency-domain research makes us analyze the unsteady flow field from a new perspective, and we can see some of the phenomena that are difficult to see in the time domain. The effect of the wake on axial velocity is very large, and in the developing process along the flow, with the increase of harmonic order, axial oscillation amplitude reduces, and the attenuation speed of the amplitude is also accelerating. The distribution of the 1st harmonic amplitude in the S3 plane is disturbed by the potential interference of the downstream blade row, and the maximum value point in the circumferential direction along the radial direction shaped as the blade profile. The effect of the wake on flow density, static pressure and total pressure is small, while the air static temperature and total temperature are greatly affected by the wake.