Load Effect on the Starting Performance of a Standing Wave Thermoacoustic Engine

Introduction A thermoacoustic engine is a device absorbing heat at the hot heat exchanger and releasing heat at the cold heat exchanger while producing acoustic work as an output. Engines are built to carry a load, which in the case of an acoustic device, might include a thermoacoustic refrigerator [4], a (possibly linear) electric generator [2] etc. Coupling between the engine and the load influences both starting performance and steady operation. The aim of the current work is to study the influence of a variable load on the onset conditions of a standing-wave thermoacoustic engine, through direct numerical simulation of the starting phase. Unstable acoustic modes develop spontaneously in the system. The computed acoustic pressure signal in the active cell is analyzed in order to extract the growth rate and frequency of the dominant modes. Therefore the critical hot exchanger temperature and frequency of the associated mode allowing the engine to start can be determined.