Method for analyzing pressure fluctuation signals based on wavelet transform

Dynamic pressure fluctuation signals were acquired in the high-temperature and high-pressure experiments of aero-engine combustors. The non-stationary characteristics of signals transitioning from stable to unstable states are analyzed using the discrete wavelet transform (DWT) and continuous wavelet transform (CWT). The results indicate that the pressure fluctuation exhibits a switching between two oscillation modes. The wavelet analysis method effectively identifies the dynamic transition process of combustor pressure fluctuation. After the transition, the pressure fluctuation manifests as limit cycle thermoacoustic oscillations at acoustic modal frequencies, while before the transition, the pressure fluctuation exhibits frequency modulation characteristics, with instantaneous oscillation frequencies varying periodically over time. Additionally, the discrete wavelet transform achieves superior early warning performance compared to the Fourier transform.