Research On The Propulsive Performance Of Dolphin Kicking Swimming

Underwater vehicle has brought great benefits to mankind and gets the attention of the countries when ocean development becomes increasingly important.The development of bionic robot dolphin is a hot research topic.This is due to the excellent swimming ability of dolphins.It is hoped that by studying the dolphin,people can improve the hydrodynamic performance of underwater vehicle.Previous studies have suggested that dolphins may have special mechanisms to reduce drag.But in recent years,research has shown that there is no special mechanism of drag reduction of dolphin swimming.The reason that dolphin can swim at a high speed is that it can generate great thrust by bending its body and tail.In this paper,numerical simulation method combined with morphing mesh technology is used to study the propulsive performance of fluke motion of dolphins.The main work is as follows:1.The research status,research objectives and significance of the research are summarized and the research method and main contents of the issue are put forward;2.The resistance of the dolphin and the thrust generated by fluke motion without coming flow are calculated.The numerical simulation results were compared with experimental data and related literature,and the agreement is good.The feasibility of the numerical calculation method is verified,which lays a solid foundation for the study of the issue;3.The influence of the phase difference which is between the bending body of the dolphin and the tail fin on the propulsive performance is studied.In addition,the concept of Quasi-propulsive efficiency is referred to evaluate the propulsion efficiency of self-propelled body.Calculation results show that the propulsive efficiency is highest when the phase difference is 90° and the reason of that were analyzed;4.The effect of St number on propulsive performance is studied.The results show that the efficiency change is not significant when the St number is between 0.25 and 0.4,which is consistent with the observation results of the literature.Finally,active chord-wise flexibility was superimposed on the tail and its influence on propulsive performance was studied.The calculation results show that appropriate flexibility of the tail fin can effectively increase the efficiency.This paper uses mathematical formula to describe the change of tail shape of dolphin.Combined with morphing mesh technology,numerical method is used to study the propulsive performance of dolphin swimming.The Quasi-propulsive efficiency is used to evaluate the propulsion efficiency of self-propelled body.The calculation results show that active deformation of the tail can effectively increase the propulsive efficiency.And these results can provide theoretical basis for the design of the flapping bionic propeller.