Amplification and saturation of the thermoacoustic instability in a standing-wave prime mover
Résumé
In this paper, a thermoacoustic standing-wave device is studied, which consists of a quarter-wavelength straight resonator equipped with a 600 CPSI ceramic stack. Transient regimes leading to steady state acoustic pressure are measured under various heating conditions and for several locations of the stack inside the resonator. Experiments show interesting behaviours such as an ''overshoot'' for the acoustic pressure before its final stabilization, or a periodic ''on-off'' of the wave. A discrete time model is proposed to reproduce these transient behaviours. For each time step, the temperature distribution along the device is computed first by solving non-linear diffusion equations, then the amplification rate of the acoustic wave is calculated from the imaginary part of the resonant frequency of the system. Nonlinear saturating acoustic effects such as the thermoacoustic heat flow inside the stack and the Rayleigh's streaming in the resonator are introduced in the model, and their impact on the dynamics of wave amplitude growth are quantified. The results show good agreement between the experiments and theory, in terms of amplification process and final stabilized pressure amplitude.
Domaines
Acoustique [physics.class-ph]Origine | Fichiers éditeurs autorisés sur une archive ouverte |
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