The deflection effect of starlight transmission in hypersonic conditions

When starlight navigation method is applied in the hypersonic vehicle, the complex turbulence generated around the window of star sensor causes starlight deflection, thus lead to the centroid offset of navigation star in the star-map imaging. Starting from characteristics of the flow field, the deflection effects of starlight transmission are researched to solve. At first, based on Reynolds average, the model of flow around the window was established to obtain the density distribution that can be divided into mean-time and fluctuation flow field to analyze the whole field. On this basis, the starlight is traced by using the Runge-Kutta method, while taking the principle of refraction, the evaluation index for starlight deflection is derived to characterize the deflection effect of the field. Finally, verify the applicability of the evaluation index through comparative analysis and also study the impact on deflection effect with the follow situations: different installation locations of star sensor, different angles of incident ray, different Mach numbers and wavelengths of starlight. The study provides the predictive information for centroid offset of navigation star in star-map pre processing to improve the efficiency of star-map matching, and also provides the best choice for the work of the star sensor..