Numerical study of a thermoacoustic impulse turbine

Thermoacoustic engines represent a new and ecofriendly way to extract energy from a heat source at high efficiency. These heat sources can be combustion, solar or low temperature sources. Depending on configuration these engines can work either based on closed Brayton cycle or on Stirling cycle which makes them theoretically (Stirling case) as efficient as Carnot cycle. They transform thermal power in acoustic power which is then converted into mechanical power using an extraction device. Apart from the extraction device the rest of the thermoacoustic engine has no moving parts which makes it extremely reliable. Energy extraction device is a critical part of this engine and several solutions have been proposed. The most interesting and the newest is the turbine proposed by Aster Thermoacoustics in 2012. This paper investigates through CFD and FEM numerical simulations the performances in transforming acoustic power in mechanical power of such bidirectional impulse turbine for different input values like frequency, gas type and gas density. The study completes previous research and helps for a better understanding of such turbine working in an acoustic field.