Assessment of the jet pump impact on thermoacoustic prime mover operation

Abstract

International audienceDuring recent decades, research institutions and industries showed an important interest to systems that perform energy conversion with high environmental and energetic performances. Thermoacoustic devices can reciprocally convert thermal energy into acoustic energy and use non-polluting fluids, nitrogen, helium or air. Due to their high environmental performances, they can potentially answer to this challenge. These machines can easily reach a coefficient of performance of about 20 % of the Carnot coefficient and few devices have achieved 40%. The results of the research proposed to the Icom18 conference deals with the study of the energy losses that occur in systems using oscillating flow under high mean pressure. The phenomenon of acoustic streaming has been identified as one of the major source of energy dissipation in thermoacoustic devices. This secondary flow which is superimposed to the first-order oscillating flow is generated by the nonlinear propagation of the high-amplitude waves occurring in thermoacoustic system. From energy consideration and despite its low level, this second-order phenomenon involves undesirable loss mechanisms. The experimental investigations on acoustic streaming, firstly qualitative became more quantitative with the development of laser measurement techniques such as Particle Image Velocimetry (PIV) and Laser Doppler Velocimetry (LDV). Theoretical linear model will be presented and experimental results of acoustic pressure and velocity will enable the validation of the different assumptions