高超声速飞行器在再入大气层的过程中面临着极端的气动热环境，目前工 程上广泛使用烧蚀材料设计热防护系统，通过材料的烧蚀反应吸收带走热量实 现飞行器结构的热防护。准确地计算再入过程中飞行器表面的烧蚀量及传入飞 行器结构的净热流，对于热防护系统的设计有重要意义。飞行器表面的材料烧 蚀不仅与材料的烧蚀性能相关，还与飞行器表面的气动参数以及再入飞行的轨 道相关。烧蚀反应过程复杂，涉及气动、烧蚀、结构热传导多物理场耦合。飞 行器表面随着烧蚀的进程实时地发生后退，在飞行器表面数值模拟中涉及动边 界的处理，是计算过程中的一个难点。 国内外学者对于烧蚀问题中的边界移动问题展开了许多研究，解决方案主 要集中在网格型数值计算方法，有生死单元法[1]、ALE网格自适应法[2]、网格重 构法[3]、边界元法[4]等。这些方法存在一些问题，ALE方法在处理大烧蚀量的问 题时，网格会变得狭长，产生网格畸变，导致计算终止。生死单元法可以模拟 大烧蚀量问题，但是新形成的界面出现非物理性的凹凸不平，影响热流边界条 件的施加。网格重构法在每一个时间步都需要重新划分网格，需要将上一步的 计算结果插值到新的网格节点上，工作量增大且会积累计算误差。 基于以上各种方法的不足，本论文引入基于粒子的无网格计算方法——光 滑粒子流体动力学方法（Smoothed Particle Hydrodynamics, SPH），实现边界移 动和结构温度场计算。无网格通过支持域内粒子完成计算，不需要预设网格建 立联系，粒子之间没有相互约束，在处理动边界及大变形问题时存在天然优势。 对比三种 SPH 算法（CSPM、SPH2、CSPH2），选定 SPH2 算法编写程序实现温 度场计算和边界移动。 本文将 SPH 方法结构热传导/烧蚀边界移动模块和气动、烧蚀计算模块耦合， 形成一个完整的烧蚀模拟程序。本论文使用气动计算工程算法，编写简单钝头 体气动参数计算模块。烧蚀模块详细分析了碳基材料的烧蚀反应模型，基于化 学平衡假设和元素在壁面的相容方程，计算边界层内各烧蚀反应生成物的浓度， 计算得到输入结构的有效热流和边界烧蚀量，输出给 SPH2温度场计算模块实现 结构的表面后退和温度场计算。 运用开发的基于 SPH2算法的多学科耦合烧蚀计算程序，对某再入飞行试验 的飞行器端头烧蚀进行模拟。对比了 SPH 方法计算结果和 ALE 方法的计算结果， 二者吻合较好，表明本论文引入无网格 SPH 方法来模拟端头的烧蚀是可行的， 结果是可信的，本论文的工作为后续大变形烧蚀的模拟打下了理论基础。

Hypersonic vehicles face extreme aerodynamic thermal environments in the process of re-entry, and currently, ablative materials are widely used in engineering to design the thermal protection system, which realizes the thermal protection of the vehicle structure by absorbing and carrying away heat through the ablative reaction of the materials. Accurately calculating the amount of ablation on the surface of the vehicle during the re-entry process and the net heat flow into the structure of the vehicle are of great significance for the design of the thermal protection system. Material ablation on the vehicle surface is not only related to the ablative properties of the material, but also to the aerodynamic parameters of the vehicle surface and the trajectory of the re-entry flight. The ablation reaction process is complex, involving multi-physics field coupling of aerodynamics, ablation, and structural heat transfer. The real-time recession of the vehicle surface with the ablation process involves the simulation of the dynamic boundary problem, which is a difficult point in the computational process. Scholars at home and abroad have carried out many researches on the boundary moving problem in the ablation problem, and the solutions mainly focus on the gridtype numerical computation methods, such as the birth-death cell method[1], the ALE mesh adaptive method[2], the mesh reconfiguration method[3], and the boundary element method[4], and so on. There are some problems with these methods, and the ALE method, when dealing with large ablation quantities, the mesh becomes narrow and produces mesh distortion, which leads to the termination of the calculation. The birthdeath cell method can simulate the large ablation volume problem, but the newly formed interface appears unphysical unevenness, which affects the imposition of heat flow boundary conditions. The grid reconstruction method requires re-gridding at each time step, interpolating the calculation results from the previous step to the new grid nodes, which increases the workload and accumulates calculation errors. Based on the shortcomings of the above methods, this thesis introduces a particlebased meshless computation method ---- Smoothed Particle Hydrodynamics (SPH) method to realize the boundary movement and structural temperature field computation. The meshless accomplishes the computation by supporting particles in the domain without the need of a predefined mesh to establish connections. There is no mutual constraint between the particles, and there is a natural advantage in dealing with large deformation problems with moving boundaries. Comparing three SPH algorithms (CSPM, SPH2, and CSPH2), the SPH2 algorithm is selected to write a program to implement the temperature field calculation and boundary movement. In this thesis, the SPH method structural heat transfer/ablation boundary shift module is coupled with the pneumatic and ablation calculation modules to form a complete ablation simulation program. This thesis uses pneumatic computational  engineering algorithms to write a module for calculating the pneumatic parameters of a simple blunt head body. The ablation module analyzes the ablation reaction model of C-based materials in detail, calculates the concentration of each ablation reaction product in the boundary layer based on the assumption of chemical equilibrium and the compatibility equation of the elements at the wall surface, calculates the net heat flow and the boundary ablation amount of the input structure, and outputs it to the SPH2 temperature field computation module to realize the surface recession and temperature field calculation of the structure. The developed multidisciplinary coupled ablation calculation program based on the SPH2 algorithm is used to simulate the vehicle end ablation of a re-entry flight test. The calculation results of the SPH method are compared with those of the ALE method, which are in good agreement, indicating that it is feasible to introduce the meshless SPH method to simulate the ablation of the end head in this thesis, and the results are credible, and the work in this thesis lays a theoretical foundation for the simulation of the subsequent ablation with large deformation.