Design and Optimization of a Blended-Wing-Body Underwater Glider

The shape of blended-wing-body underwater glider (BWBUG) is an important factor in determining the hydrodynamic efficiency. In order to reduce the needed computation time and efforts during the search of the optimum shape, a new surrogate-based shape optimization framework is proposed to solve the complicated BWBUG shape design optimization problem in this paper. During the search, seven baseline airfoils are used to build the parametric geometric model of the BWBUG, with the planar surface being fixed. Moreover, a newly proposed ensemble of surrogates based global optimization algorithm using a hierarchical design space reduction method (ESGO-HSR) is employed to optimize each baseline airfoil. Then, the optimum shape of the BWBUG can be determined and rebuilt based on all baseline airfoils that are successful optimized. As the optimization target, the maximum lift to drag ratio of the initial design is increased by 13.72% under the given operating conditions. The results demonstrate that the presented surrogate-based shape optimization framework is efficient and capable in identifying the optimum shape of the BWBUG.