Research On Hydrodynamic Characteristics Of Amphibious Bionic Robot Based On CFD

Amphibious bionic robots can complete desilting tasks of small and medium-sized rivers and lakes,wetlands and marshes because of its flexible amphibious movement ability.At the same time,amphibious bionic robots can also be equipped with a variety of work devices,so they are used more and more widely in a variety of hydraulic engineering.Because the current development of Chinese amphibious bionic robots is slow,there are disadvantages in amphibious bionic robots' performance.Hydrodynamic characteristics are important for economy,stability and safety of amphibious bionic robots,so this paper take amphibious bionic robots of type A and type B as the research objects and research the hydrodynamic characteristics of them by numerical calculation based on computational fluid dynamics(CFD).This paper provides guidance for amphibious bionic robots' design,development and optimization.In this paper,the VOF method is used to simulate the free liquid surface,and the overlapping grids and the DFBI motion model arc used to calculate the movement of the amphibious bionic robots caused by fluid force.The accurate static floating states of amphibious bionic robols of type A and type B were obtained by numerical calculation and the advantages and disadvantages of the two kinds of static floating states were compared and analyzed.Then the sailing resistance of the two amphibious bionic robots at 2m/s sailing speed was predicted,the sailing attitudes were obtained and the water resistance of the important parts of the amphibious bionic robots was analyzed.Taking roll,pitch and heave three kinds of motion as the main research conditions of free swaying motions in static water,the free swaying motions in static water of amphibious bionic robots were simulated by numerical calculation and the corresponding parameters of these three kinds of free swaying motions were obtained.The regular wave parameters under different wind levels were calculated by using Putian test station formula.The swaying motions of amphibious bionic robots in regular waves under different wind levels,different sailing speeds and different course angles were calculated by using differential equation of swaying motion.According to the research on the seakeeping of amphibious bionic robots,A set of evaluation method of comprehensive seakeeping design for amphibious bionic robot was designed and the comprehensive seakeeping design of amphibious bionic robots of type A and type B was compared.Taking amphibious bionic robot of type B as the optimization objects,three kinds of different breakwaters were installed.The sailing resistance of different breakwater schemes at 2m/s sailing speed was predicted and the sailing resistance and sailing attitudes of three breakwater schemes were compared and analyzed.Then the rear-cutting angle of amphibious bionic robot of type B was changed and the sailing resistance of different rear-cutting angle schemes at 2m/s sailing speed were predicted.The sailing resistance and sailing attitudes of different rear-cutting angle schemes were compared and analyzed.Finally,by adjusting the elongation of the hydraulic cylinders of the front legs to change the position of the front legs,the free roll processes in static water of schemes with different positions of front legs were simulated and the roll reduction ability of different positions of the front legs was studied.