Impact of cross-sectional area ratio on time-averaged pressure drop induced by jet pump for thermoacoustic engine

Gedeon streaming, a time-averaged mass flow circulating throughout the loop configuration in the oscillating flow, can considerably deteriorate the thermal efficiency of traveling-wave thermoacoustic engine. Jet pump is characterized by a tapered channel with different inlet and outlet areas. It can produce a time-averaged pressure drop to suppress Gedeon streaming. In this study, the suppression mechanism of the jet pump in oscillatory flow is investigated, and the emphasis is put on the effect of cross-sectional area ratio on the performance of jet pumps with different taper angles. An experimental apparatus has been built to measure the time-averaged pressure induced by the jet pump. When the taper angle ranges from 3° to 9°, the time-averaged pressure drop and working efficiency can be improved by increasing cross-sectional area ratio, and the change of taper angle has little effect on the performance of jet pumps. However, as the taper angle increases beyond 9°, the performance of jet pump with a large cross-sectional area ratio degrades considerably. In addition, the time-averaged pressure drops induced by the jet pumps with different cross-sectional area ratios are similar, and the taper angle becomes more dominant for jet pump's performance.