Numerical Simulation Of Micro-scale Combustion Characteristics Of AP/HTPB Propellant

To study the micro-scale steady combustion process under various pressure and different AP mass fraction conditions as well as the micro-scale unsteady combustion under initial 480MPa/s depressurization rate of the AP/HTPB composite propellant,a simplified 2D periodic sandwich unit was established and.numerical simulated based on the background of combustion of solid rocket engine The combustion characteristics such as flame temperature,AP/HTPB mass ratio,heat release rate and burn rate was analyzed,the results are:(1)Numerical analysis of AP/HTPB composite propellant combustion under different pressure conditions.Pressure is one of the dominant factor of propellant combustion and influences their burning characteristics.ICEM and Fluent was used as the tools to investigate the influences,the main parameters are as follow,the pressure are range from 0.3MPa to 7.2MPa,the AP mass fraction are 76%,furthermore,the diameters of the AP/HTPB model are 110μm.Results show that there are three kinds of flame structure when the pressure ranges from 0.3MPa to 7.2MPa,they are 1)pre-fixed flame during 0.3MPa to 0.4MPa,2)both pre-fixed flame and diffusion flame during 0.4MPa to 2.4MPa,3)diffusion flame during 2.4MPa to 7.2MPa,moreover,the temperature of the interface between solid and gas increases as the pressure is increasing,which means the higher of the pressure,the bigger thermal feedback from gas phase to solid phase,the burning rate is soar as the higher pressure(2)Numerical analysis of AP/HTPB composite propellant combustion under different AP mass fraction ratio.The influence of AP mass fraction on the AP AP/HTPB composite propellant steady combustion was obtained by fluent simulation,during the simulation process,the pressure was constant and equaled 2.4MPa,and the only factor-AP mass fraction was changed from 0.76 to 0.95.According to the results,we can learn that with the increasing AP mass fraction,the separated flame band above the AP/HTPB interface diffusese through the gas interaction zone and becomes a whole,moreover,the heat feedback of the interface between solid and gas decreases as the AP mass fraction ratio increasing,and the burning rate as well as the combustion gas velocity is decreased as the higher AP mass fraction ratio.(3)Numerical analysis of AP/HTPB composite propellant combustion under initial 480MPa/s depressurization rateIn order to obtain the characteristic parameters such as flame temperature,species heat release and burning rate during the unsteady combustion of the AP/HTPB composite propellant,the Fluent is used to numerically simulate the combustion process under 480MPa/s depressurization rate The results show that during the unsteady depressurization process,the inhomogeneity of flame temperature distribution in the gas phase region decreases gradually,and the temperature deceased along the process,moreover,the components of the combustion process diffuses with each other,compared with the diffusion of the pyrolysis,chemistry reaction of the decompositions of the AP/HTPB was the dominate factor during the combustion process.The heat release decreased while it’s influences regional among the gas domain increased,and the average burning surface temperature as well as the average burning rate show three different decreasing trends and finally tend to be stable.