Research On Hydrodynamics Properties Of Underwater High-speed Towfish

High speed towing technique has received much attention all around the word due to its high efficiency. As the underwater platform of high speed towing, the high-speed towfish plays a critical role in the operation of high speed towing technique. In this thesis, the hydrodynamics of high-speed towfish is studied to provide references and foundation for the subsequent optimization, attitude control and design of entire towing system, and the main points are as follows:1. Through numerical simulation analysis on high-speed towfish employing CFD technique, the hydrodynamics analyses on primary model of high-speed towfish, such as drag, lift and pitching moment were carried out. The calculation and simulation on flaps and heads with different shapes was also conducted to analyze its hydrodynamics properties and obtain the optimal towfish shape.2. The mechanics analyses of high-speed towfish based on the law of Newtonian Mechanics and Kinematics were performed, and three-dimensional kinematic model was developed and the longitudinal motion equation with three-degree freedom was obtained. Through CFD technique, the position power parameters and damping parameters were solved out. And combined with longitudinal motion equation of high-speed towfish and position power parameters and damping parameters, the balance angle of attack with non-acceleration linearly motion of high-speed towfish was analyzed to confirm the optimal flap. Moreover, the static stability and dynamic stability of high-speed towfish was analyzed.3. Based on the potential flow theory and panel method, the added mass of high-speed towfish was obtained by AMass calculation program. Employing water wave theory, the longitudinal heaving disturbance velocity was determined, and longitudinal motion heaving response equation was obtained with the combination of disturbance velocity and three-degree freedom longitudinal motion equation. Additionally, the variable step-size Runge-Kutta method was used to solve the longitudinal motion heaving response equation.