*Rotating stall is an unsteady flow phenomenon* *occurring in the* *flow* *rate* *reduction process of* *axial compressor. Single or multiple stall* *cells* *can be found in the blade passage,* *rotating circumferentially* *at a* *frequency ranging from 20% to 80% of compressor rotational frequency. Rotating* *stall may further* *lead to* *serious surge phenomenon, then the mass flow and pressure ratio of the compressor decrease rapidly while the vibration amplitude of bearing fulcrum increases significantly, which would* *affect safety operation of the* *aero-engine. The* *midline of meridion flow path of axial compressor is usually parallel or nearly* *parallel to the rotating shaft* *axis. Numerous previous studies on rotating stall and surge are based on this conventional type.* *However, few reports have* *concentrated on* *such studies of multistage compressor with special-shaped aggressive flow* *path. *

*To study the* *rotating stall and surge characteristics of multistage compressor with* *inlet distortion, this paper takes a 4.5-stage axial compressor as the research object which has* *a* *special S-shaped meridian* *flow path.* *On SJTU large-size compressor test facility,* *the author carries out compressor transient performance* *tests of several subjects (measuring* *stator LE/TE* *and inter-stage* *wall fluctuating pressure by blade type fluctuating pressure transducers, measuring bearing fulcrum vibration by* *acceleration transducers,* *and measuring dynamic stress* *by* *pasting strain transducers on the surface of stator blade). And in the subsequent* *surge experiment, several stall phenomenons and its induced surge signals at different rotating speeds are* *successfully captured . With the above test data, time domain analysis,* *frequency domain fast Fourier transform* *and auto-correlation analysis are used to preliminarily analyze the signal evolution process from rotating stall to surge, circumferential and axial propagation law and stall characteristic prediction. Meanwhile, the instantaneous frequency of stall process signal is extracted by estimating the optimal kernel parameters, parameterized time-frequency analysis method* *is further adopted to capture the changing rules of the signal instantaneous frequency in above process, and the transient performance characteristics of multistage compressor with special S-shaped flow* *path from* *rotating stall to surge conditions are analyzed in detail. The results indicate that, compared with traditional methods, the parameterized time-frequency method* *are more effective in characterizing the strong time-varying signals such as* *rotating* *stall and surge.*


The Investigation of Axial Compressor With Aggressive Flow Path Near Stall Condition

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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