Shape Design And Motion Analysis Of Blended-wing-body Underwater Glider

The advantages of gliders,such as low cost,capability for long-range and extendedduration deployments,rely on the shape which has excellent hydrodynamic performance.In this paper,the author applies blended wing body configuration to design the shape of underwater glider to improve the hydrodynamic performance,and focuses on the study of the blended wing body shape optimization design method of underwater glider.The main results and innovation are as follows:(1)The geometric parameters and hydrodynamic characteristics of three kinds of the main body of underwater glider are analyzed and compared.Among this three main bodies,the flat ellipsoid have better hydrodynamic characteristics,so it is more suitable for the main bodies of blended-wing-body underwater glider(BWBUG).Based on that,different fusion approaches are analyzed and compared,the underwater glider with full airfoil section is selected as the initial shape of BWBUG.(2)According to the characteristics of BWBUG,it is divided into the airfoil profile,the plane shape and the spanwise thickness distribution respectively.By writing matlab code,the transformation from the shape parameters to the 3D model of BWBUG has been realized.(3)The shape optimization of BWBUG is a typical problem of expensive black box,so a mathematical model based on the Kriging surrogate model is established to solve this problem.In the iSIGHT software,the shape optimization platform of BWBUG is established.Then,the platform is used to optimize the shape of the underwater glider,and the optimization results are analyzed to find out the influence of geometric parameters on the hydrodynamic performance of the underwater glider.(4)Based on the analysis of the force acting on BWBUG,a mathematical model of six degrees of freedom motion of BWBUG is established.The CFD method is used to calculate the hydrodynamic parameters of the BWBUG,such as additional mass,position force and rotational derivative.The steady gliding motion of the glider is simulated and its motion characteristics are analyzed.(5)A mathematical model for steady state motion of BWBUG is established.According to the working principle of the steady motion,the energy consumption model is established.Then,the internal volume and the energy carrying capacity of BWBUG are quantified,and the mathematical model of the underwater glider is established.The shape optimization model of BWBUG is established with the maximum range as the optimization objective,and the shape optimization is carried out.