湍流对超音速导弹光学图像的影响数值仿真

Numerical Simulation of Turbulent Flows' Effect on Optical Images in Supersonic Missiles

利用大涡模拟得出湍流瞬态密度值 ,并根据Gladstone Dale关系计算出飞行器周围流场的折射率 ,从而为定量研究导弹导引头光学性能提供依据。首先依据大涡模拟理论对Navier Stokes方程进行滤波 ,建立可压缩湍流亚格子模型和大涡模拟方程。根据物理光学理论 ,计算了光学点扩散函数 (PSF)。数值仿真结果表明 :湍流对导弹光学系统图像将产生抖动、畸变和图像破裂等影响。这些影响与来流马赫数、飞行高度和攻角密切相关。定量得出的结果为下一步进行光学图像校正奠定了基础。

The transient density of turbulent flows is calculated by applying large eddy simulation (LES), and the index of refraction for fluid of interceptor is given, which provides data for the study of optical performance of the seeker quantitatively. Navier stokes equations are filtered based on the LES methods, then, the subgrid scale model and LES equations for compressible turbulence are built up. Based on physical optics theorem, point spread function (PSF) is calculated. The simulative results show that the effects of turbulent flows are jitter, distort and breakup on optical images, which relate with Mach number of free flow, altitude and attack angle. The quantitative results provide materials for correcting of optical images.\;