Experimental and Numerical Studies on the Performance and Mixing Characteristics of Supersonic Annular Ejector

The performance of the supersonic annular ejector is affected by the mixing characteristics between the primary and the secondary flows. In this work, experimental and numerical methods are used to study the ejector performance and mixing characteristics of the annular ejector. The annular ejector has an equal-area mixing chamber (EAM) and a conical mixing chamber (CMC) with the convergence ratio of 0.7, and the Mach number of the primary flow is 4.2. The experimental results verify the accuracy of the numerical simulation, and they also show that the minimum startup pressure of the annular ejector is inversely proportional to the convergence ratio. Meanwhile, due to the presence of hysteresis characteristics, reducing the primary total pressure after startup allows the ejector to maintain a high ejector performance. In the CMC, the mixing develops faster for the more intense turbulent motion. Variations in entrainment ratio (ER) and total temperature ratio (TR) alter the spatial location distribution and the turbulent kinetic energy of the mixing layers, which in turn affects the rate of mixing development. Lower ER and TR result in faster mixing development. However, since the mixing layer in the annular ejector is confined by the wall, the change of mixing rate is non-linear with the change in ER and TR.