System Design And Performance Analysis Of Hybrid-driven Underwater Glider

Autonomous underwater glider (AUG) is a new type of autonomous underwater vehicle (AUV) propelled by buoyancy. AUGs have many advantages, such as low noise, low cost, and long endurance in the order of several thousand kilometers. But they can only travel in a sawtooth pattern at a low speed. AUVs are usually driven by a propeller. They have high maneuverability and velocity, but their range is relatively short, usually up to an order of hundreds of kilometers. This paper develops a hybrid-driven underwater glider PETREL by combining the advantages of AUGs and AUVs. PETREL is equipped with both buoyancy-driven system and propeller- driven system.This paper focuses on the mechanical system of the hybrid-driven underwater gliders. The whole system is designed in detail. The characteristics of main hydrodynamic components are studied using Computational Fluid Dynamics (CFD). The equilibrium characteristics and motion stability are studied based on the general equations of motion. All the expected design capabilities of the AUG are fulfilled. The analysis and simulation results were verified by lake trials. The main contributions of this thesis are summarized as follows:1. A prototype of the hybrid-driven underwater glider PETREL is proposed to achieve the goal that one underwater vehicle can glide with the buoyancy-driven system and maintain level flight with the propeller-driven system.2. The dynamic model of PETREL is formulated. The hydrodynamic parameters are obtained using CFD software and a visual dynamics simulation software is developed using Matlab. The software facilitates parameter evaluation and design of PETREL.3. Characteristics of the main hydrodynamic components of PETREL are analyzed and optimized using CFD method. The results provide the hydrodynamic basis for design of wings and rudders, and give the hydrodynamic characteristics of the propeller shroud and the flow field.4. The efficiency of buoyancy-driven and the efficiency of navigation of AUGs are defined. Detailed analysis and calculation of these two efficiencies are carried out. Factors that impact the buoyancy-driven efficiency and the navigation efficiency are revealed. The parameter study provides a theoretical guidance for high-performance underwater glider design.