Numerical Simulation Study Of Thermal Ablation And Protection Of The Matrix Material Of Rocket Launcher’s Directional Tube

With the improvement of the performance of the rocket artillery weapon system,the ablation problem of the directional tube has become increasingly serious,which affects the firing accuracy of the rocket artillery system.In this paper,epoxy resin,which is the base material of the directional tube,was used as the research object to study its ablation characteristics under aerodynamic heat and understand the ablation mechanism of the directional tube.The epoxy resin will appear obvious layering phenomenon in the ablation process,which are ablation layer,char layer,pyrolysis layer,and virgin layer.As the temperature of the material increases,the epoxy resin will first be thermally decomposed and generate pyrolysis gas,which will be induced to the gas boundary layer through porous char layer,and the ablation wall will be receded.Complex heat transfer and mass momentum exchange occur on the surface and the interior of the material under the coupling effect of surface ablation and volume ablation.The ablation mechanism of epoxy resin under aerodynamic heating was analyzed in terms of both energy conversion and mass conversion,then a mathematical model of macroscopic materials including thermal decomposition and thermal blocking effects was established.The thermal response model of the control body was established based on Fourier’s Law,the pyrolysis kinetics model was established by Arrhenius equation,and the flow model of pyrolysis gas in porous carbon was established based on Darcy’s Law.The finite element simulation analysis was then performed based on the mathematical model,and the simulation results of the epoxy resin in aerodynamic heating process were compared with the results of nonlinear analysis of thermal properties based on finite difference method to verify the feasibility of the mathematical model.Subsequently,the influences of chemical kinetics,external heat flux,material thickness,and heating time on ablation characteristics of charring thermal protection materials were analyzed.The ablative coating was used to improve the thermal protection of the directional tube,mainly considering its oxidation and volatilization mechanism under the high-temperature gas,which further provides the theoretical basis for the selection and design of the directional tube material.