Aerodynamic Design of Payload Fairing of Satellite Launch Vehicle

Abstract

This paper presents computation of aerodynamic coefficients for various bulbous heat shield of a typical satellite launch vehicle at supersonic speeds. Numerical simulations are carried out by solving time-dependent, three-dimensional, compressible Euler equations in conjunction with a finite volume scheme at freestream Mach number 1.2 and 1.8 which are, respectively, corresponding to the conditions of maximum aerodynamic drag and dynamic pressure experienced by the satellite launch vehicle during the ascent period of the trajectory. The numerical scheme captures all the essential flowfield features of high speed flow such as a formation of bow shock wave, compression and expansion region over the bulbous payload shroud. A controlled random search method is employed to obtain required geometrical parameters of the bulbous heat shield that will satisfy the prescribed aerodynamic loads conditions at Mach 1.2 and 1.8. The controlled random search algorithm does not need computation of derivatives. The algorithm works even when the differentiability requirements cannot be ensured in the feasible domain and also the starting condition is not crucial. The computed normal force distributions and centre of pressure are compared with wind-tunnel data and are found in good agreement between them. The determination of the optimum geometrical parameters of heat shield for the prescribed aerodynamic loads is essential to maintain the structural integrity of the payload fairing during ascent phase of the launch. The CFD approach with the CRS will help to reduce the number of costly and time consuming wind tunnel testing.