Volume 16: Low Carbon Cities and Urban Energy Systems: Part V

Investigation on Oscillations Characteristics of Self-Excited Thermoacoustic System Forced by Acoustic Wave Lulu Hu, Yingwen Liu

Abstract

Self-excited thermoacoustic oscillations usually occur in many practical systems such as rocket motors, gas turbines and cryogenic distribution systems. We study the dynamics of a self-excited cryogenic thermoacoustic system subjected to acoustic forcing. The effect of the driving phase on the amplitude of forced oscillation is analyzed. The results show that the variation of driving phase has not affected the maximum amplitude of pressure oscillation. The coupling oscillation characteristics are clarified through the phase portraits. By analyzing the data with Poincare map, we found a range of nonlinear dynamics, including (i) a shifting of the 1-period oscillation towards k-period oscillation as the forcing phase increases; (ii) an accompanying transition from single-frequency model to two-frequency model. The results suggest that such oscillators can be used to represent thermoacoustic selfexcited systems subjected to similar forcing.

Keywords Thermoacoustic oscillation, Instability, Heatto-sound conversion, Active control