基于声学信息的航空发动机压气机旋转失速空间特征实验研究

Rotating stall in aero-engine compressor is a serious aerodynamic instability phenomenon，the current research is mainly based on the time-frequency analysis of the signal measured by intrusive pressure sensors，and its spatial characteristics are not sufficiently studied. In this paper，a forced surge experiment on a realistic aero-engine compressor with 3.5 stages was conducted by closing the throttle valve at a uniform speed in 9800 r/min，32 acoustic array sensors were arranged uniformly around the circumference of the inlet casing，and the acoustic signals during the experiment were measured. Frequency spectrum analysis，cross power spectral density and short-time Fourier transform methods are used to identify rotating stall and its precursor features. The results show that there are non-synchronous pressure pulsation at frequencies of 7.73EO and 8.48EO（EO is rotational frequency）before the rotating stall，and its circumferential propagation speed is greater than the rotational speed. A modal wave precursor occurs at 65 rotations before the rotating stall，which was spatially characterized by a low-pressure region propagating steadily in the circumferential direction at a speed of 0.67 times the rotational speed. After the onset of the rotating stall，the stalled air mass propagated in the circumferential direction at a speed of 0.45 times the rotational speed，and the spatial characteristic of the modal wave is the same as the stalled air mass，which both occupy half of the blade channel. By monitoring the rotating stall precursors，the prediction of the characteristics of the stalled air mass can be realized.