The angle between high pressure port and middle pressure port is one of the most important structure parameters for gas wave ejector. In this study

the influence of this angle on the performance of gas wave ejector is analyzed by numerical simulation and experiment. The prediction method for the optimal angle is proposed. For any given conditions

there is an optimal angle ψopt. When the angle is greater than the optimal one

a reflected shock wave is generated and the isentropic efficiency of gas wave ejector decreases significantly; While the angle is less than the optimal one

the efficiency declines slightly for the case of lower middle pressure. However

if the middle pressure is higher than pM-extra

the pressure inside the channel after a cycle is lower than that at the middle pressure outlet. A compression wave is produced when the channel is exposed to the outlet

so the efficiency drops sharply as the port angle decreases. The calculation results agree well with the experiment data

so the model could predict the optimal angel effectively. When the temperature and pressure of the inflows are constant

the optimal angels at different middle pressure are almost the same

but increase linearly with the rotation speed. The above conclusions provide guidance for gas wave ejector design and optimization.