Analysis of flow characteristics and flow stability on an axial compressor with inlet temperature ramp distortion

This paper concentrates on the effect of inlet temperature ramp distortion on the compressor flow field, characterized by a rapid rise and quick recovery of the compressor inlet total temperature. RANS, URANS, and harmonic balance method are used to accurately calculate the compressor flow field under temperature ramp distortion conditions. An analytical model based on small perturbation theory is employed to predict the compressor stall point. This model approximates the time-varying inlet distortion as periodic flow and uses a time-spectral matrix to assemble flow field data at different time points into a system eigenvalue matrix to assess the compressor stability. The single-stage subsonic compressor TA29 is used as the research subject. Based on URANS (Unsteady Reynolds-Averaged Navier-Stokes) calculations, compressor stall occurs when the temperature ramp rate reaches 300-320 K/s. The analytical model predicts a stall point at 295 K/s, showing a relative difference of approximately 5 % compared with URANS results. This indicates reasonably good agreement between the two methods. Simulation results reveal that elevated inlet total temperature triggers rapid load accumulation near the blade tip leading edge, ultimately inducing stall. Analysis of near-stall operating points demonstrates a positive correlation between temperature ramp rate and inlet total temperature. However, simple empirical fitting fails to accurately determine the critical temperature threshold. Instead, stall inception is governed by two integral factors: the inlet total temperature and the cumulative effect of exposure duration exceeding the critical temperature threshold.