Motion Performance Analysis Of The Mini-underwater Vehicle In Non-uniform Flow Field

Mini-Autonomous Underwater Vehicle (mini-AUV) is unmanned underwater equipment.Because of its small volume, low resistance and good maneuverability, mini-AUV gets moreand more attention all over the world, in the field of ocean science research and marineenvironment exploration. While the mini-AUV is working, it is easy infected by irregularwave, current and vortex because of the limitations of its propulsive and control system. Howto adapt the complex marine environment and control the navigation and work status is theproblems mini-AUV must face. In order to solve these problems, this paper uses the CFDtechnique to study the motion performance of different mini-underwater vehicles innon-uniform field and also some other related flow interference phenomenon.1. The CFD technique is used to predict the steady hydrodynamic performance of differentmini-underwater vehicles in the uniform field, and to analyze the influence of turbulencemodel. The dynamic mesh is applied to calculate unsteady hydrodynamic performance ofsix-degree freedom motion of the mini-AUV. Based on these calculations, the steady andunsteady hydrodynamic performance of the flat body motion are calculated in linear andparabolic velocity distribution uneven flow fields to analyze the influence of navigation statusand the non-uniform flow on the hydrodynamic performance of mini-underwater vehicle.2. The experiments of hydrodynamic performance of mini-underwater vehicle in complexflow field are conducted in Harbin Engineering University basin. The three dimensionalcomplex flow fields are generated by underwater pump and the flow is circulated in the watertank. The three dimensional velocities are measured by Doppler current profiler. Thethree-dimension velocity distributions of complex flow fields are compared when the pumpfrequency and quantity are different. The three component balance is used to measure thedrag, lateral force and yawing moment of the flat body with different drift angle in differentpositions of complex flow field. Then the hydrodynamic performance of the flat body isanalyzed in complex flow field.3. The fluid dynamic performances of square cylinder are calculated under differentReynolds numbers. And an upstream plate is set to control the flow around the squarecylinder. The flow patterns of the square cylinder are systematically investigated for different sizes and positions of the control plate, and the fluid dynamic performance is calculated inthese conditions. The calculation results showed that the upstream plate can reduce thefluctuating force on bluff body.