Research On Flow Process And Design Optimization Of HYLTE Nozzle

This research mainly studies the hypersonic low temperature (HYLTE) nozzle used in the DF/HF chemical laser system. Using a combination of theoretical analysis, numerical simulation and experimental observation, with introducing advanced design optimization method, the mixing characteristics of the injection jet into supersonic flow, the flow patterns and mixing process of the HYLTE nozzle, the design and the optimization technique of the HYLTE nozzle are investigated systematically and comprehensively.The performance evaluation method for HYLTE nozzle was established. The mixing performance of the nozzle was evaluated with introducing relative unmixedness and a synthesized performance target was proposed. The hybrid RANS/LES method available for calculations of injection crossing into supersonic flows was developed.Using a combination of various flow-displaying technique and numerical methods, the flow patterns and the mixing characteristics of injection crossing into supersonic flow were investigated and analyzed comprehensively. The change tendencies of the mixing characteristics with the change of injection stagnation pressure and the injection angle were studied. The flow patterns and mixing characteristics of fuel injection with tandem multi-orifices and parallel multi-orifices in a supersonic flow were investigated. With varying the distance among the tandem multi-orifices and that among the parallel multi-orifices, the change tendencies of the flow patterns and mixing characteristics of injection into supersonic flow were studied systematically.The structure design method of the HYLTE nozzle was proposed. The number of single nozzles, the surface parameters, the position parameters and the base configuration parameters were designed using element design method. The contrived HYLTE nozzle could fulfill basically the requirements of needs for laser structures.The numerical simulation program of HYLTE nozzle and optical cavity was developed, mainly based on the hybrid RANS/LES method. The flow and mixing patterns were calculated and analyzed. The results showed that the reactant-surface stretching and distorting are the main characters of the flow in injection-type HYLTE nozzle.The effects of the stagnation pressure in the oxidizer nozzle, the diluter nozzle and the fuel nozzle on the performance of HYLTE nozzle were studied systematically. Through changing the number of single nozzles, the surface parameters of single nozzle, the position parameters of singe nozzle and the base configuration parameters, the effects of the above parameters on the performance of HYLTE nozzle were investigated and compared comprehensively.The parameterized design method was established. The dependency-relation and the sensitivity of the key parameters of HYLTE nozzle were analyzed. The adaptive polynomial response-surface method was chosen as a substitute method and the configuration of HYLTE nozzle was optimized in the design space which is determined by the parameterized design method. Contrast to the fundamental configuration, the synthesized performance of the optimized configuration I and II is improved 65.5% and 72.3% respectively under the design operation condition. Using the parameter effecting analysis method, the effects of the configuration parameters of HYLTE nozzle on various performance parameters were studied. The results showed that the factor which affects most obviously on the nozzle performance is the injection angle of the secondary nozzles, and the distance among the secondary nozzles takes the second place.