Study On Three-Dimensional Flow And Photo-Thermal Radiation Effect Of Rocket Engine

For the engineering application requirements of rocket engine flame infrared detection and base radiant heating,the research theme of the three-dimensional flow and photo-thermal radiation effect of the flame is established,and the general purpose of the three-dimensional flow,radiation modeling and algorithm of the flame is established.The type of flame radiation signal and the flame radiation is based on heating calculation model and algorithm.Analyze the influence law of the three-dimensional effect on the flame flow,radiation signal,substrate heating,infrared detectability and other issues,thus providing a model for related engineering applications and data support.A computational and analytical model for the coupling of aerodynamic flow and jet flow is established.The typical characteristics and generation mechanism of three-dimensional jet flow are studied and clarified.Starting from the problem of the coupling between the jet flow and the aerodynamic flow in the engine under flight conditions,a computational and analytical model of the coupled flow around the missile body and the jet is established.The model considers complex boundary type,boundary state,flow around,flame wave structure,reactions of afterburning,non-equilibrium effects of particles,etc.In the coupled model,the wave structure of aerodynamic flow and jet flow is simulated by k-ε-Rt three-equation turbulence model and high-precision TVD numerical scheme.Multi-component mixed flow and finite-rate chemical reactions were used to simulate the reactions.Equivalent continuous phase model is used to deal with the non-equilibrium effect of particles.The far-field boundary model is used to deal with the complex boundary conditions.The calculation model is checked and analyzed by combining the engine mooring experiment of jet flow with the published literature data.The typical state of jet flow,the reactions of afterburning,the coupling of pneumatic jet and the three-dimensional distribution of multi-nozzle flow are calculated and analyzed in detail.The results show that the temperature distribution and composition distribution of the jet flow are significantly changed by the reactions and the three-dimensional state,and then the heating effect at the bottom of the jet and the radiation effect of the jet are also significantly affected.An algorithm of radiation characteristics of three-dimensional jet based on narrow-band model is established.The influence of three-dimensional effect of jet on radiation characteristics was found and analyzed.Based on the theory of radiation and scattering transmission of high temperature gas and particles,the reliable calculation of flame radiation signal can be realized by using narrow-band model combined with optic ray method.The problem of flame radiation produced by liquid rocket engine or mixture of gas and carbon black particles is solved.A Monte Carlo method based on the idea of radiation splitting is proposed for calculating the radiation physical parameters and radiation transfer of gas-solid two-phase jet produced by solid rocket motor.For the radiation heating problem of the jet base,a reverse Monte Carlo algorithm for the radiation heating of the base is presented by combining the combined narrow-band k-distribution model with the reverse Monte Carlo method,so as to improve the computational efficiency.Calculating model is checked and analyzed by using foreign open data and laboratory flame measurement data.Based on this model,the spectral characteristics,spectral energy characteristics and spatial distribution characteristics of axisymmetric nozzle plume radiation,the three-dimensional effect of multi-nozzle plume radiation signal and the three-dimensional effect of plume radiation basement heating are analyzed and studied.The variation of infrared radiation of engine exhaust flame with altitude and spectral band is obtained.In order to analyze the influence of infrared radiation from complex earth atmosphere background on the detectability of engine exhaust flame in flight state.Based on JHU terrain spectral database,spectral radiation characteristics of vegetation,water,rock and other terrain objects are analyzed,and spectral correlation based conversion model of terrestrial radiation band is established.Using MODIS remote sensing data products and MODTRAN software,the infrared images of the earth’s atmospheric background radiation under different detection conditions are simulated.According to the detection angle of the sensor,the infrared radiation of the engine exhaust flame and the background radiation are superimposed according to the angle,and the infrared radiation image of the exhaust flame and the background is generated.From the point of view of image quality,the image quality evaluation parameters such as information entropy,variance and signal-to-noise ratio are determined,and the detectability of the flame is analyzed.