Research On Hydrodynamic Performance Simulation Of Rays Based On CFD

As calls of exploring ocean and utilizing Marine resources growing, the boom of researching underwater-propellers with more excellent hydrodynamic performance is also coming. Because of the superior performance of the bio-inspired mode, the bionic robot-fish has become a hotspot of current researches. However, the lack of study on bionic robot-fish's mobility causes the bionic robot-fish hard to apply to a complex space and modes of the underwater operations. According to this problem, in this paper, we use rays as the bio-inspired mode, which have good mobility, to study the steady-state swimming performance when the bionic robot-ray achieves steady swimming mode.According to the biological characters of rays, we establish a physical model of the bionic robot-ray. Then, combined with the existing research results we put forward its kinematics model. Through the simulation of MATLAB, the correctness of the kinematics model is proved. Then based on the rigid body dynamics theory, we put forward the dynamic equation of the biological characters of rays. According to the related parameters in the equation we put forward corresponding algorithm and finally gain the complete dynamic model. On this basis, we have realized steady self-propulsion swimming of the bionic robot-ray in the flow using FLUENT software, and preliminary analyzed its hydrodynamic performance in time domain. The comparison with the existing results proves the validity of the model and simulation reliability. Based on the content, we have analyzed the three basic motion parameters of rays– the frequency, wave number and amplitude of pectoral fins. Using the control variable method, we have analyzed them and their hydrodynamic performance with the concept of amplitude control factor, and got the rule of how to choose the parameters for the bionic robot-ray. At the same time, we have analyzed the movement mechanism of rays preliminarily through the research of pressure distribution when the bionic robot-ray reaches stability self-propulsion swimming.Then, we start to study the frequency of pectoral fins deeply. According to the control algorithm presented in this paper, we give pectoral fins in two different wave frequencies in a cycle, and analysis the influence which the size of the two frequencies caused.In this paper, we have analyzed the hydrodynamic performance and the motion planning of the bionic robot-ray through a series of theory and simulation research above, revealed the rule that the three kinds of motion parameters influence on the hydrodynamic performance, and improved the kinematics model successfully and preliminarily. All the results in this paper laid the foundation for the further study of the simulation analysis, the model improving and prototype manufacturing.