An improved model of the aircraft plume is proposed to analyze the effects of alumina particle clusters on ultraviolet (UV) radiation signature. In the simulation, the scattering effect of particle clusters rather than individual particles on the radiation characteristics in the plume is considered. The modified diffusion-limited aggregation (DLA) method is used to generate the geometry of the cluster example and the scattering characteristics of the particle clusters are calculated by multi-sphere T-matrix method (MSTM) at first. Then the average optical properties of the particle clusters are calculated and applied to improved spherical harmonic discrete ordinate method (SHDOM), together with a new source term about the chemiluminescence emission in the plume, the improved radiation model is constructed carefully. The simulation results show that at a small observation angle, alumina particle clusters can significantly enhance the radiance of the plume comparing to the individual particle model. Meanwhile, the radiance distribution of a more realistic three-dimensional(3-D) plume is presented when both the radial and axial property variation of a whole plume structure are concerned in this model.

提出了一种改进的飞机羽流模型，以分析氧化铝颗粒簇对紫外线辐射特征的影响。在模拟中，考虑了粒子簇而不是单个粒子对羽流中辐射特性的散射效应。改进的扩散限制聚集（DLA）方法用于生成团簇实例的几何形状，并且首先通过多球体T矩阵法（MSTM）计算粒子团簇的散射特性。然后，计算了粒子团的平均光学性质，并将其应用于改进的球谐离散离散纵坐标法（SHDOM），再加上有关烟羽中化学发光的新的源项，精心构建了改进的辐射模型。仿真结果表明，与单个颗粒模型相比，在较小的观察角度下，氧化铝颗粒簇可以显着增强烟羽的辐射度。同时，当在模型中同时考虑整个羽状结构的径向和轴向特性变化时，将呈现更逼真的三维（3-D）羽状体的辐射分布。