Abstract

Thermoacoustic engines are device that converts heat energy into work in the form of acoustic energy. The energy conversion using thermoacoustic techniques has the ad-vantages of constructional simplicity, absence of moving parts, reliable operation, long ser-vice life and no environmental pollution. However, efficiency of thermoacoustic systems still needs to be improved (which is typically 40% of the Carnot coefficient of performance). To improve the efficiency of thermoacoustic engine, a thorough understanding of the flows in machines, onset temperature, acoustic velocity and streaming velocity is necessary. In this study, numerical simulation of a thermoacoustic heat engine is performed. The possibility of using Implicit Large Eddy Simulation (ILES) to simulate the flows in the thermoacoustic en-gine has been examined by using COMSOL Multiphysics. Unlike the Large Eddy Simulation (LES), ILES is neither explicit filtering nor explicit subgrid model: small-scale fluctuations are damped by the numerical diffusion, which acts both as an implicit filter and an implicit built-in subgrid model for a given grid. As the grid is refined, the simulation converges to a DNS. The results show that the ILES has predicted flows in the thermoacoustic engine and especial-ly time-averaged flow called acoustic streaming, which can lead to undesired heat convection and loss of efficiency.

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