Research On Internal Ballistic Modeling And Flow Field Characteristics Of Small Robot Underwater Launching Device

With the continuous development and improvement of China’s economy and the extension of "21st century Maritime Silk Road",it is inevitable to realize China’s strategy of becoming a maritime power to safeguard national security,develop Marine science and technology and develop Marine equipment.Over the past ten years,due to its simple structure,small dimensions,large combat radius and low cost of use,underwater unmanned vehicle(UUV)has become a new research hotspot underwater equipment in various countries all over the world.How to use light weight and small size UUV has become a difficult point restricting the development of new UUV.In this context,this paper takes the underwater launching system of a small robot as the research object,establishes a mathematical model of the launch system,and analyzes the underwater launching process of the robot using numerical simulation and experimental verification methods.The primary work consists of the following components:Firstly,according to classical interior ballistics,thermodynamics,aerodynamics and other theories,establish a mathematical model of the interior trajectory of the underwater launching system of a small robot,and use the fourth-order Runge-Kutta method to perform numerical solution to obtain interior trajectory parameters and robot displacement,velocity varies throughout time.Secondly,based on the established mathematical model of the internal ballistics of the underwater robot launching system,analyze the influence of the air source pressure,the volume of the gas cylinder,the opening area of the launch valve,the opening time of the launching valve and the launching water depth on the internal ballistic performance of the underwater robot launching system,and then use the particle swarm optimization to complete the optimization calculation of important undetermined parameters.Thirdly,based on the physical and mathematical model provided by the Fluent software,this paper conducts a two-dimensional axisymmetric numerical simulation of the underwater launch tube process of a small robot,and realizes the grid structure of the robot launch process by using a regional grid division method for the calculation model.It uses the VOF(Volume of Fluid)model to simulate the deformation of the air-water interface during the robot egress process.The dynamic grid technology and the six-DOF solver are used to realize the coupling calculation of the robot flow field and the robot motion.The characteristics of the flow field and the robot’s motion law of the robot during the robot exit process.Fourthly,design an experimental system for the underwater launch of a small robot,complete the underwater launch experiment of the robot,use a high-speed camera to capture the evolution of bubbles during the underwater horizontal launch of the robot,obtain the kinematics characteristics of the robot,and perform numerical simulation results compare and analyze with experimental results.