Hydrodynamic Characteristics And Motion Simulation Model Construction Of A Pectoral-Fin Propeller

At present,there are many underwater bionic studies focused on body and/or caudal fin(BCF) locomotion.However,we notice that many fishes' propulsion systems perform well for both efficient cruising and high maneuverability at low swimming speed by using paired pectoral fins.This is called median and/or paired fins(MPF) locomotion. Up to now ,few researchers enter in this domain for the MPF's mechanism isn't explicit.In this thesis,according to Azuma's analysis to the beating motion of a bird's wing,four fundamental motions were gave: a rowing motion, a flapping motion, a feathering motion and a spanning motion,which made up pectoral fins' complicated labriform motion.However,the spanning motion was neglected because the pectoral fin was considered as a rigid paddle.In this thesis,on the basis of the theory of potential flow,we derived the unsteady vortex lattice method(UVLM) from Hess-Smith panel method by using equivalence of normal dipole and vorticity distribution.Then programmed and computed the hydrodynamic coefficients when the pectoral fin's motion model was two degrees of freedom and three degrees of freedom.Moreover the factors which affected on the pectoral fin's hydrodynamic characteristics were analyzed.The left and right pectoral fins' added mass were computed by applying Hess-Smith panel method.Then we constructed the robot fish's motion simulation model by applying motion equations of six degrees of freedom,it was based on a bionic underwater vehicle "FangSheng- I " developed by Underwater Vehicle Technology Lab,Harbin Engineering University.And we analyzed the simulation results,with emphasis on straight cruising and turnning.The computational hydrodynamic coefficients need to be validated by experiments,and wake model is not perfect.In the future,we could consider a new method to compute the hydrodynamic coefficients by applying.Navier Stokes equation.