Shape Optimization of Blended-Wing-Body Underwater Gliders Based on Free-Form Deformation

Jinglu Li,Huachao Dong,Peng Wang,Xu Chen

doi:10.1051/jnwpu/20203830459

Abstract

Currently developed underwater gliders can be roughly divided into the two types:traditional configuration and unconventional configuration. As a type of underwater gliders with unconventional configuration, a blended-wing-body (BWB) underwater glider has better fluid dynamic performances because of its unique shape. However, it is difficult to design the shape of the BWB underwater glider that has excellent hydrodynamic performances. Therefore, it is of great significance to optimize its shape, which this paper carries out by using the free-form deformation (FFD). The complete and automatic shape optimization framework is established by jointly using FFD parameterization method, CFD solver, optimization algorithm and mesh deformation method. The framework is used to optimize the shape of a BWB underwater glider. The average drag coefficient of the BWB underwater glider during its sinking and floating in one working period is used as the objective function to optimize its shape, with the volume constraints considered. The optimization results show that the gliding performance of the BWB underwater glider is remarkably enhanced.

Highlights

Shape Optimization of Blended⁃Wing⁃Body Underwater Gliders Based on Free⁃Form Deformation
Currently developed underwater gliders can be roughly divided into the two types: traditional configura⁃ tion and unconventional configuration
It is difficult to design the shape of the BWB underwater glider that has excellent hydrodynamic performances

Summary

Introduction

绘制其外形 FFD 控制体如图 3 所示。控制体共计 120 个控制点,内部嵌有滑翔机表面网格,利用 FFD 参数化实现建立控制点与几何表面网格节点的映射关系。按照以上要求提出外形优化问题: 目标函数为最小化一个周期运动的阻力因数。设计变量为 FFD 控制点的位移,控制点可以沿 x,y,z 3 个方向运动(命名为 x,y,z)。约束条件为体积不等式约束。完整的外形优化设计问题如表 1 所示。本文对一种翼身融合水下滑翔机开展了外形优化设计研究,提出了一套外形优化框架,包括 FFD 参数化方法用于参数化, CFD 求解器用于数值模拟,网格变形算法用于计算网格更新,SQP 算法用于优化迭代。外形优化设计以最小化一个周期运动的平均阻力系数为目标函数,在保证体积约束的情况下,翼身融合水下滑翔机一个周期的平均阻力系数降低了 16.45%,同时在下沉与上浮阶段的阻力系数均得到了降低。 WANG Dan. Approach and Application Research on Aerodynamic Shape Optimization Design[ D] .

Results

Conclusion