Effect of external sound superimposed on the self-excited oscillation in loop-tube thermoacoustic system

Abstract

Abstract The influence of application of external sound to loop-tube type thermoacoustic system on the energy conversion efficiency is experimentally examined. The investigation is carried out by paying attention on the effect of loudspeaker (SP) set as external sound source. As a result, it is found that the setting of SP affects the sound field in the system and the amount of energy generation increases or decreases. The increasing or decreasing effect differs depending on the setting position of SP. Furthermore, it is confirmed that, provided SP is set near the node of particle velocity, the sound energy can be increased by more than the input power to SP, without changing the sound field in the tube. From these results it can be confirmed that, similar to straight-tube type thermoacoustic system, the energy conversion efficiency can be enhanced by setting SP at suitable position even in loop-tube type without end surfaces.