Resonance control by setting a phase adjuster or expanding phase adjuster for improving the performance of coaxial-type thermoacoustic system

Sound field control to suppress resonance transition from fundamental mode to secondary mode, that was a significant problem in coaxial-type thermoacoustic system, is examined by modifying the acoustic tube. The experiments are carried out by applying a phase adjuster (PA) or an expanding phase adjuster (EPA) which has been used for a different thermoacoustic system. The position for installing PA or EPA is determined based on the experimental results for the sound field. It is demonstrated that the suppression effect of the secondary mode is enhanced as the thickness of PA or the inner diameter of EPA increases and PA and EPA then affect the phase of the sound field in the tube. Furthermore, an advantage for actual application that the phase at the setting position of HP approaches the phase of traveling wave and the system performance is improved by the increased traveling wave component is also confirmed.