Influence of transverse structural vibration on the nonlinear dynamics of Rijke-type subcritical thermoacoustic system

This study numerically investigates the impact of external transverse structural vibration on the nonlinear dynamics of a subcritical thermoacoustic system. A comprehensive analysis is conducted using various methods, including time series analysis, reconstructed phase portrait, spectrum analysis, and wavelet analysis to characterize the system's response. When the thermoacoustic system operates in the globally stable region, the acoustic pressure amplitude exhibits a monotonic increase with the vibration amplitude, with resonant conditions leading to significantly higher system responses compared to non-resonant cases. In the hysteresis region, high-amplitude vibrations are found to trigger thermoacoustic instability at any frequency, with lower heater temperatures requiring higher vibration amplitudes. Under non-resonant conditions, low-frequency vibrations require lower amplitudes to trigger instability compared to high-frequency vibrations. Once the system becomes unstable, external structural vibrations exert a modulating effect on the high-amplitude limit cycle oscillations. The present findings provide valuable insights into the complex interaction between structural vibration and thermoacoustic instability in thermoacoustic systems, advancing the understanding of these phenomena and their implications for the design and operation of practical combustion devices.