三维烧蚀内部热响应数值计算研究

对热解型碳化复合材料三维烧蚀内部热响应数值计算关键技术进行了研究。采用碳化层—热解面—原始材料层模型,将热解气体与碳化层之间的对流换热处理为源项,通过有限元法建立移动边界条件下温度场求解方程组,采用Gauss-Seidel迭代法计算热解气体质量流量和温度场。同时,研究和分析了三维烧蚀移动边界处理方法以及动网格生成方法。由于每个时间步都需要网格重划,烧蚀热防护数值计算对存储效率和计算效率要求较高,本文研究了内部热响应计算中影响存储效率和计算效率的主要因素,并提出了相应的压缩存储方案和求解方案。计算结果表明,移动边界处理方法准确合理;存储方案的存储效率较高;保持刚度矩阵和形函数矩阵正定对称性可以加快温度场计算的收敛速度。

Numerical Simulation Research on Three-Dimensional Internal thermal Response of Ablation Thermal Protection

The key technology of numerical simulation of internal thermal response of carbonized composite material with pyrolysis reaction was researched deeply.Charred layer-pyrolysis surface-original material model was applied and convection heat transfer between pyrolysis gas and charred layer was treated as heat source.The linear equations of three dimensional temperature field were built with finite element method under moving boundary condition.The temperature field and pyrolysis gas mass flux were calculated with Gauss-Seidel iteration method.At the same time,the method of dealing with moving boundary and dynamic mesh generation of three-dimensional ablation was researched and analyzed.Because the mesh need to be regenerated in every time step,numerical simulation of ablation thermal protection had high demand in data storage and calculation efficiency.This paper researched the main factors that affected the storage and calculation efficiency.The method of compression storage and solution was presented.It is demonstrated by calculation results that the method of dealing with moving boundary is correct and proper,the storage method has high efficiency and it can speed up convergence of temperature field calculation by keeping the conductance matrix and capacitance matrix positive definite symmetric.