The Propulsion Behavior Of Fish Using Energy In Flow Field And Swimming Trajectory Planning Research

At the present time, the fish-like submarine propeller always is a focus in the bionic research field, which has high capabilities of propulsion and high maneuverability. The fish-like submarine propeller could be used in the underwater environment for a long time, with wide-range performance. Moreover, it can be used for the research on the ocean life, ocean observation, life saving and military areas. It has very high value of application. Depends on the Self-Planned Task of State Key Laboratory of Robotics and System (HIT), the basic theory of mechanic characteristic of carangiform fish swimming is developed.In this paper, we research how fish use the energy of Karman vortex from active and passive aspects. By analyzing the relationship between flow field parameters and the movement parameters of fish, we found 5 fundamental parameters determined the performance of fish in Karman vortex field, including stream velocity, cylinder diameter, the distance between fish and cylinder, fish wave length and amplitude. We control the fish movement in the vortex field actively by changing 5 parameters, and analyze their effects to the performance of fish. We advanced Self-made fish swimming in the trajectory planning method, this method proved the phenomenon that fish can feel the energy to go ahead in upstream. We analyze three kinds of movement patterns when fish are on the different positions behind the cylinder, and explain the reason for movement patterns theoretically.In the research how fish use the energy from the vortex of the front fish, we analyze the effects to vortex distribution of tail amplitude, wavelength, frequency and the stream velocity. Order to distinguish the different nature of the wake vortex, we use Struhar number to be the evaluating standard. In the study of double fish swimming, we changed the value of wavelength, frequency, phase, vertical and horizontal distance, to analyze their effects to the performance of back fish, and compare with swimming of single fish. We found that double fish on one line can decrease the resistance of liquid, and swimming in the triangle array is the best way for shoal.In this paper we use the method of CFD simulating analyzing. Via this research, the parameter combination how fish the the energy of Karman vortex and converse Karman vortex best is gained, and the energy exchange between the fish and flow field is preliminarily discussed. All of these would provide theoretical and simulation basis for the development of the passive-dynamic Robot Fish and its motion control.