弹头包络目标辐射传递系数的蒙特卡洛计算

Monte Carlo Method for Calculating Radiative Heat Transfer Coefficient of Warhead Envelope Target

为了计算镜面反射的气球内表面和漫反射的导弹弹头外表面之间的辐射传递系数,建立了包络目标的面元剖分模型。然后,选取发射面元,利用蒙特卡洛方法生成发射光线并对光线进行路径追踪,获取线面碰撞发生时的面元吸热和光线反射信息,计算发射面元与全体面元之间的辐射传递系数,并在完全灰体条件下验证了方法的正确性。气球镜面反射率ρs=0.9、弹头漫发射率εc=0.8时的计算结果表明:气球内表面的某发射面元(面元中心天顶角55°、方位角55°)对气球全体面元的辐射传递系数存在两个明显的峰值,对弹头表面存在一个峰值区域;弹头表面的某发射面元(面元中心方位角55°,母线长度1.68m)对气球内表面和弹头表面各存在一个辐射传递系数峰值区域。

In order to calculate the radiative heat transfer coefficients between the specular and diffuse surfaces,a faceted geometry was setup to represent the gray missile warhead object inside a specular balloon. Rays emitted from one facet（ i. e.,emission facet） are generated by using Monte Carlo method.Multiple reflections for each ray are traced until it is totally absorbed. Energy absorbed at each ray-facet intersection is recorded to calculate the heat transfer coefficient between the emission facet and any other facet. The method is firstly validated in a gray-facet system,and then used to deal with the system composed of specular balloon and diffuse warhead,with specular reflectivity ρs= 0. 9,diffuse emissivity εc=0. 8. Results indicate that,here are two peak areas in the matrix of the radiative heat transfer coefficient for the specular inner surface of the balloon,and one peak area for the diffuse surface of the warhead when the emission facet（ the zenith and azimuth of the facet center are 55° and 55°） is selected from the balloon. However,there is only one peak area in the matrix of the radiative heat transfer coefficient for the specular inner surface of the balloon as well as the warhead when the emission facet（ facet center is at azimuth 85°, generatrix length1. 68 m） is selected from the diffuse surface of the warhead.