Open-air traveling-wave thermoacoustic generator

Abstract

Taking the input and reflected waves into account, the relationship between the acoustic impedance at the end and the input of a system were theoretically analyzed. Closed and open acoustic configurations that influence the pressure, volumetric velocity, impedance and acoustic work were compared in detail. Based on the above investigation, an open-air traveling-wave thermoacoustic generator was designed and fabricated. It is composed of a looped tube, a resonator open at one end, a regenerator, and hot and cold heat exchangers. It is a small scale and simple configuration. The resonant frequency is 74 Hz at 1 bar in air. The maximum acoustic pressures at the open end and 0.5 m far away from the open end are 133.4 dB and 101 dB from a reference value of 20 μPa when the heating power was 210 W, respectively. Acoustic pressure is reasonable for practical application as a low-frequency acoustic source. In further work, we believe that the acoustic pressure at the open end can achieve 150 dB, which could be a solution to problems in existing acoustic generators. These problems include low acoustic pressure and system complexity. It can be used as a basic acoustic source for low frequency and long-range noise experiments, and as a supply for high acoustic pressures necessary for industrial sources.