Research On The Hydrofoil Propulsion Principle And Its Bionic System

The hydrofoil propulsion is a exploratory research topic in the new pattern propulsion field for the underwater vehicle. Research on the hydrofoil propulsion principle and performance, analyzing and investigating the hydrofoil propulsion manipulation method of bionic system, then providing both theoretic and technical supports for the research and application of bionic underwater vehicle, have important research meaning and practical value.This thesis primarily did the research on the hydrofoil propulsion principle, including the dynamic model of hydrofoil propulsion, flexible distortion, hydrodynamic performance and so on. Furthermore, based on the preceding referred results, the carrier technology of hydrofoil propulsion is investigated, and the theoretic conclusions are validated in the experiments.Based on the research of biological prototype structural characteristics and movement characteristics, the hydrofoil propulsion principle was analyzed. Utilizing the rubbings photocopy method, hydrofoil and palmiped’s physiological parameters were obtained, as the reference for hydrofoil propulsion analysis and bionic mechanism research. Analyzing the image information which was obtained by the multi-camera vision real-time testing experiment platform, the variation of characteristic angle of the hydrofoil was used to describe the hydrofoil propulsion states, and the hydrofoil propulsion manipulation method was investigated. Combining the theoretical analysis and hydrodynamic experiments, the hydrofoil propulsion principle was analyzed from the aspects of fluid dynamic action mechanism of hydrofoil, similarity criterion, unsteady flow field effect and so on, the relationship between yawing torque and maneuverability of hydrofoil propulsion was studied.Research on the dynamics model of hydrofoil propulsion, the thesis established the two DOF mathematical model of hydrofoil motion; through the analysis of general transformation matrix and research on hydrofoil mechanics jacobian matrix, the kinematics equations and dynamic models of hydrofoil were obtained. Based on the research of hydrofoil motion hydrodynamics by use of differential element method, the hydrodynamics of hydrofoil propulsion body was analyzed from the aspects of fluid damping simplified and fluid additional mass. The dynamics model of hydrofoil propulsion body was educed from the Newton-Euler equations, providing a importance reference to the gesture control of hydrofoil propulsion and a simulation platform for the development of hydrofoil propulsion controller.For the nonlinear distortion problem of flexible hydrofoil, the deformation analysis of hydrofoil flexible structure was made from the two aspects of deformation equations and modal analysis. The chord-wise distortion and span-wise distortion of flexible hydrofoil were analyzed; and it is demonstrated that the flexible hydrofoil model with half skeleton support was better than the one with entire skeleton support, from the aspects of flexible deformation amount and the change of propulsive efficiency which were caused by the variation of stroke-water angles.Studiing on the hydrodynamic performance of hydrofoili propulsion, through the hydrodynamic numerical simulation and flow field analysis, the parameter influence law and scaling law effect of hydrofoil motion were investigated. Based on the hydrodynamics analysis of hydrofoil propulsion, the hydrodynamic forces and yawing moments under the change of movement parameters were numerically simulated. The results of simulation demonstrated that the stroke spin angular velocity, azimuth spin angular velocity and azimuth spin time ratio have an influence on the linear navigation propulsion, and the yawing control effect of their differential. By using of the Fluent software, the simulation solved the Navier-Stokes equations of hydrofoil motion model, analyzed unsteady flow field evolvement and its mechanism of hydrofoil motion, validated the theoretical analysis of fluid action such as eddy circumfluence and capture of wake current, illuminated the influence law that hydrofoil wingspan length and chord length had the effect on the acceleration distribution and propulsion mean value of hydrofoil propulsion, provided the important gists to optimization design of the flexible hydrofoil. Based on the hydrodynamic performance analysis, a control strategy of bionic hydrofoil propulsion was put forward. For validating the correctness of the analysis of hydrofoil propulsion principle and the feasibility of hydrofoil propulsion, a bionic system of hydrofoil propulsion was developed and its experments was researched. The design and debug of the perceptual system, control system, communication system and energy system in the carrier were all accomplished, the system integration of experiment carrier was completed, and a technical discussion about the microminiaturization of it was also made. Through the single limb experiments of moving parts, the angular velocity distribution characteristics of both stroke spin and azimuth spin motors were investigated. From the aspects of static texts, the movement performance texts and the flexible propulsion experiments of the system, the analysis of mechanism of hydrofoil propulsion, the dynamic model, the influence law of parameter variation on hydrofoil motion, and the feasibility of hydrofoil propulsion were all verified by experiments. The hydrofoil motion experiments had verified the validity of control strategy of the bionic hydofoil propulsion, and the experimental results of flexible hydrofoil had showed that the propulsion effect of flexible hydrofoil during the high-speed phases was better than the rigid one, and validated the simulation conclusion that flexible hydrofoil could improve the efficiency of hydrofoil propulsion.