Nonlinearity Suppressed by Applying Phase Adjuster in Thermoacoustic System

Abstract

A phase adjuster (PA) has been proposed to improve the energy conversion efficiency of a loop‐tube‐type thermoacoustic system. A PA is a device for increasing the particle velocity of the sound by narrowing part of the loop tube. In this experiment, we present a discussion of the efficiency of heat‐to‐sound energy conversion in a loop‐tube‐type thermoacoustic prime mover, emphasizing the nonlinearity suppressed by PA. It is found that the sound intensity with PA is greater than that without PA. This means that the efficiency of heat‐to‐sound energy conversion is improved with PA. Results obtained in this experiment reveal that the nonlinearity of the self‐sustained sound generated in the loop tube is suppressed by placing PA. It is known that the acoustic streaming induced by the nonlinear effect decreases the energy conversion efficiency. It is considered that the suppression of nonlinearity results in the suppression of acoustic streaming, and consequently the energy conversion efficiency is improved.