Perspective Chapter: Computational Modeling for Predicting the Optical Distortions through the Hypersonic Flow Fields

Optical aberrations caused by supersonic/hypersonic flow files can lower the guidance accuracy of high-speed flying interceptors with onboard infrared guider. This chapter mainly summarizes the related research achievements on these issues based on the past works. First, the current developments on this important topic are discussed comprehensively. And secondly, the basic theories for predicting the aero-optical distortions used in this chapter, that is the computational flow field dynamics and its characteristics used for establishing the relationships with the flow fields and the optical light, are carefully provided. And then the density field of the flow field acquired from the large-eddy simulation (LES) can be transformed into the refractive index field in terms of the Gladstone-Dale relation. Recursive ray tracing method of optical propagation through the flow of fluids is given out. In the following, the chapter discusses the information optical modeling approach for the solutions to this issue. In the flow fields, every CFD grid is thought of as a uniform and isotropic cell. This chapter utilized the angular spectrum propagation theory for considering the optical waves propagating cell by cell. The suggested method can give out the optical transformation function (OTF), which can be directly used for modeling the aero-optical image. In the end, this chapter concludes the research works and points out the future development and potential applications of these presented research works.