Effects of temperature difference and operating pressures on heat-driven acoustic characteristics and nonlinear behaviors in a looped tube traveling wave thermoacoustic engine

Abstract

In this work, the output heat-driven acoustic characteristics and dynamic thermal-fluid flow fields in a looped-tube traveling-wave thermoacoustic engine (TWTAE) are numerically investigated. Emphasis is placed on optimizing acoustic power output from the TWTAE by varying its operating pressure and temperature difference across the regenerator. For this, a time domain full-scale 3-D traveling-wave TAE model is developed, and then validated by comparing with those results obtained from the experimental data available in the literature. The present results indicate that the acoustic pressure oscillations and the acoustic power are increased with increased operating pressure of the working gas. Furthermore, nonlinear acoustics and flow dynamics in the heat-driven acoustic and flow fields of the TWTAE such as vortex generation around the regenerator and Gedeon streaming are observed. Considering the comprehensive acoustic characteristics, the optimal heat-driven acoustic power output, and thermo-acoustics energy conversion efficiency are achieved, as the working air pressure is set to 0.4 MPa. Increasing the temperature difference across the regenerator can further improve the acoustic power output from the TWTAE. In summary, the present 3-D model can be used as a design tool for predicting and optimizing looped tube traveling-wave TAE performances with detailed thermos-fluid dynamics and acoustics characteristics.