基于有限元法的大气层外弹道式目标表面温度场分析

摘要

It is an important prerequisite to obtain surface temperature field on a target in the research on infrared characteris-tics. In this paper, a finite element (FE) model was developed to determine the surface temperature field of an exoatmospheric ballistic target. Radiation boundary condition was taken into account in the two-dimensional transient heat transfer FE model, which was built in the cylindrical coordinate system according to the axisymmetric distribution of the temperature field in the target. This paper strictly analyzed the radiation heat loss of nonisotbermal finite element, and derived the expression of the radiation heat loss off a three-node axisymmetric triangular element. In order to use the Galerkin method to solve the time differential equations set, the radiation heat loss was treated as a heat load term dependent on time. Using the Newton-Raphson method, the nonlinear equations set was solved iteratively. A simple nmnefical experiment demonstrates the effectiveness of the present method. In the end, the surface temperature fields of the exoatraospheric ballistic target was analyzed by the triangular element.%获取目标表面温度场是进行红外特征分析的重要前提.为确定大气层外弹道式目标的表面温度场分布,建立了有限元模型.根据目标温度场的轴对称分布特点,在柱坐标系内建立了二维瞬态热传递模型,从而降低了计算量.与当前大部分的有限元软件和文献不同,严格分析了温度非均匀性有限单元的辐射热损失,并推导出轴对称三结点三角形单元的辐射热损失公式.为了能够使用Galerkin法求解时间微分方程组,将辐射热损失视为与时间相关的热载荷项,并用Neon-Raphson法迭代求解处理后得到的非线性方程组.一个简单的数值实验表明了所提出方法的有效性,最后应用该法求解了目标飞行全程的表面温度场分布.