Kriging-based shape optimization framework for blended-wing-body underwater glider with NURBS-based parametrization

Abstract Lift-drag ratio has an important impact on the horizontal range of Blended-Wing-Body Underwater Glider (BWBUG). It is significant to increase the lift-drag ratio of BWBUG for a longer horizontal range. In this paper, a Kriging-based shape optimization framework for the BWBUG with NURBS-based parametrization is proposed to maximize the lift-drag ratio and to improve the optimization efficiency. In this framework, a shape parameterization method of BWBUG is presented based on the NURBS method, to precisely calculate the geometric constraints and their gradient information. The CFD method is applied to accurately compute the hydrodynamic parameters of BWBUG in the whole optimization design. A Kriging-based optimization framework is built with dynamically infilling sample points to update the Kriging model by the aid of the gradient information of geometric constraints, which further improves the optimization efficiency Finally, the effectiveness of the proposed optimization framework is verified by performing the shape optimization of a BWBUG.