Investigation on transient process of thermoacoustic oscillation in a gas–liquid standing-wave thermoacoustic engine

This work focuses on the transient process of thermoacoustic oscillation in a standing-wave thermoacoustic engine with gas–liquid coupling oscillation. Observing the transient evolution of the pressure amplitude shows that the on-off phenomenon can occur through adjusting the location of the stack in the acoustic field, and there exists a critical distance from the stack center to the pressure antinode for this phenomenon to occur. The analysis from the perspective of energy balance indicates that energy dissipation induced by liquid surface instability is a key factor contributing to the occurrence of on-off phenomenon. Through installing a submerged float into the liquid column to stabilize the liquid surface, the on-off phenomenon can be suppressed. Besides, the temperature difference for achieving steady thermoacoustic oscillation is decreased and the steady-state pressure amplitude is increased. In this work, the significance of liquid surface instability on the transient process of thermoacoustic oscillation is revealed and should be considered for better characterizing the dynamics of gas–liquid thermoacoustic engines.