Design Theory, Method And Experimental Investigation Of High Compression Ratio Multi-Nozzle Supersonic Ejector

The theory and methods for designing a supersonic ejector were comprehensively examined, a quasi-two-dimensional flow model was established to analyze the start and eject performance of supersonic ejector with a fixed second throat; a high compression ratio multi-nozzle supersonic ejector was designed and constructed; and start and load matching characteristics of the multi-nozzle supersonic ejector were investigated systematically with experimental and numerical methods.With a nozzle configuration factor introduced, the control volume equations for center injection, annular injection and multi-nozzle injection were consolidated; parameter optimization models were established for constant area ejector, and constant pressure ejector and second throat adjustable perfect ejector, respectively. Furthermore, the influences of design parameters on ejector performance were studied.A quasi-two-dimensional flow model was presented to analyze the start and eject performance of an ejector with a fixed second throat, and the influences of design parameters on the start and eject performance were studied. In this model, method of characteristics and Korst recompression criterion were combined to calculate the cell pressure; one dimensional control volume analysis was integrated to iterate the second throat contraction ratio limit and the minimal start pressure ratio; constant pressure turbulent mixing model was used to analyze the mixing effect, and an alternative method was brought up to simplify the calculation for high compression ration ejector.A model ejector with variable geometrical throat was designed, then, the processes of start and unstart were investigated, and a criterion was proposed for the condition that second throat is too small to start. Several resolutions were presented to settle the unstart problem, and the relative merits and the applicability of each resolution were analyzed.A high compression ratio modular multi-nozzle supersonic ejector was designed, and a test facility was established. On the test facility, start performance was researched experimentally, with rocket exhaust being used as primary working medium. The influences of nozzle assemble configuration, nozzle profile, second throat contraction ratio and the coupling of nozzle assemble configuration with ejector duct on the start performance were investigated experimentally and numerically. The results showed that: nozzle profile and the coupling of nozzle assemble configuration and ejector duct have great influence on the ejector start performance.With hot rocket exhaust produced by simulator being used as secondary flow, plentiful experiments were carried out to investigate the characteristics of load matching of the multi-nozzle supersonic ejector, and the results showed that the requirements of secondary flow on the capability of entrainment and pressure matching can be fulfilled by the multi-nozzle supersonic ejector. The effect of primary flow total pressure and total temperature on the eject performance, the influences of secondary flow inlet condition on the requirement of eject performance, and the influences of geometric parameters on the capability of entrainment and pressure matching were investigated. Finally, Secondary flow was suggested to be a booster to improve the start performance under lower operation condition creatively.