Abstract: In the field of aerospace engineering, supersonic ejectors find extensive applications, typically for suctioning second-ary flows and generating low-pressure environments. This paper proposes a novel design of a precooled supersonic ejector to enhance its performance. The ejector adopts a dual-nozzle structure with sturt and incorporates a precooler to precool secondary flows with temperatures exceeding 1100 K. Through a combined approach of experimental and numerical methods, the starting characteristics, operating characteristics, and the influence of precooling secondary flows on the performance of the precooled supersonic ejector are analyzed. The research findings indicate that when the total pressure of the primary flow exceeds 3.0 MPa, the precooled supersonic ejector can start completely, with the suction chamberpressure stabilizing at 3.4 kPa. However, in the critical starting state, the ejector flow channels do not achieve full supersonic flow, and shock trains affect the suction chamber. In the fully starting state, the two jets collide after accelerating out of the nozzles, leading to an initial rise followed by a decrease in static pressure near the nozzle exit. Conversely, when the ejector is under operating mod, there is an initial decrease followed by an increase in static pressure near the nozzle exit. Additionally, regardless of starting or operating conditions, shockwave intersections and reflections exist in the ejector flow channels, forming diamond-shaped regions, which gradually disappear with an in-crease in secondary flow rate and its temperature. Under conditions of low entrainment ratio, precooling secondary flows effectively enhance the mixing efficiency of the primary and secondary flows, but this advantage diminishes at high ejector coefficients. Furthermore, precooled passive flows can effectively increase the compression ratio of the ejector, with enhancement exceeding 33.3%.

Key words: Supersonic ejector, precooler, flow field, mixing, shock waves