Numerical and Theoretical Investigations on Twin Standing-wave Thermoacoustic Prime Movers

Abstract

In this work, we perform computational fluid dynamics investigations topredict the performance of the twin thermoacoustics engine (TAE) undervarious working gas/medium and at different charge pressures. The numerical model is validated by comparing with those of DeltaEC (Design Environment for Low-amplitude ThermoAcoustic Energy Conversion) predictions and previous experimental results. Additionally, the effects of (1) the geometry shape of the twin TAE and (2) different types of working gases on its performance are examined. The results indicate that the working gas/medium and charge pressure in the engine are critical to the twin thermoacoustic engine. Although the acoustic pressure amplitude is higher with air or nitrogen as the working gas, the acoustic oscillation frequency is higher with helium or argon and the value of the acoustic growth rate is larger, i.e., the limit cycle is observed growing faster in the twin TAE. Furthermore, the pressure-ratio is increased in the tapered resonator, because its velocity amplitude is decreased. It means the tapered resonator is the best choice for the twin TAE. The acoustic characteristics predicted are much closer to the experimental results than those of DeltaEC estimations, which provides a design tool for designing and predicting performances of twin TAEs.