Multipoint Nose Shape Optimization of Space Launcher Using Response Surface Method

Abstract

A multipoint optimization technique has been implemented to improve the performance over a wide operating range for the shape design of a nose fairing to a space launcher. The response surface method is implemented to reduce the computational effort during optimization. For the optimization model, the drag represents the objective function, and the design constraints are based on the maximum allowable surface heat transfer and the minimum internal volume for the nose fairing. The data for the response surfaces are obtained by solving the Navier-Stokes equations. The key flight events are simplified for efficient multipoint design, and separate response surfaces have been constructed for each design point. The response surfaces are combined together with a weighting factor to construct an objective function. Optimization through separate response surface and weighting functions shows good effectiveness for the two test cases: drag minimization and combination of drag/heat-transfer minimization. Finally, with the validated optimization approach, the space launcher nose shape, which undergoes the least drag during the whole flight mission while satisfying given heat-transfer constraint, is designed. The shape function approach and the nonuniform rational B-spline curve approach are implemented and compared for modeling the nose geometry. The optimization approach proposed in this study results in a nose fairing shape of the launcher that has a 24% improved drag characteristic when compared to the baseline shape.