基于流固耦合的固体发动机复合喷管烧蚀型面演变

Due to the different ablation properties of the materials， ablation steps are common in composite nozzles of solid rocket motors， which seriously affects the structural integrity of the nozzle and reduces the nozzle performance. In order to predict the evolution of the ablation step pattern at the intersection of different thermal protection materials in the composite nozzle of a solid rocket motor， a fluid-solid coupling calculation method was developed to reflect the ablation process of thermal protection materials in the two-phase flow environment of the nozzle. Based on the mechanism of thermochemical ablation and particle erosion， the evolution process of the ablative surface of graphite-high silica phenolic compound nozzle was simulated by considering the regression of the ablative surface in the transient calculation， and the effectiveness of the calculation method was verified. The simulated ablative step of convergence section was in good agreement with the experimental results， while the calculated step depth of expansion section was lower than the experimental value. Simulation results show that： the convergent section is subjected to a combination of thermochemical ablation and particle erosion， the difference in particle erosion rate between the two materials up to 0.36 mm/s， which is the main reason for the formation of ablation steps in the convergence section. The generation of ablation steps in the expansion section is only affected by thermochemical ablation， the maximum difference in receding rate at the intersection is 0.044 mm/s. After the formation of ablation steps， the exposed graphite material at the corners will be subject to a strong particle scouring effect. The actual throat of the nozzle moves 1.96 mm towards the outlet due to ablation of the graphite material at the front of the nozzle throat.