CFD grids-based transmission model of the rays propagating through the hypersonic flow field

Aero-optical aberration caused by hypersonic flight can hazard the imaging quality and lower the guidance accuracy, so it is necessary to research the optical transmission through the hypersonic flow field. The density field acquired from the large eddy simulation (LES) was mapped onto the refractive index field in terms of the Gladstone-Dale relation, and the model that the rays transmit through the layers of the refractive index cell was built based on the CFD grids. So the geometrical optics was used, and a recursive ray tracing method of optical propagation through the flow of fluids was derived. Using different flow field data and different angles of incidence, the optical path difference (OPD), the optical path length and the ray coordinate excursion were calculated. The influences of altitude, the Mach number and the angle of incidence on the optical propagation through the turbulent flow fields were discussed. This transmission model is the foundation of predicting the optical wave-front performances.