Research On Hydrodynamic Performance Of Micro-small Underwater Vehicle

In recent years,as the number of the Earth's population continues to increase,ecological environment pollution,and depletion of terrestrial resources have become more and more serious,human beings are increasingly aware of the importance of marine resources.As an intelligent underwater unmanned equipment,the micro-miniature unmanned underwater vehicle plays a huge role in marine resource exploration,hydrological investigation and submarine pipeline construction.However,at present,domestic and foreign docks,bridge piers,reservoir dams,ships,etc.,in the narrow,water-contaminated and dangerous shallow water environment,the construction and regular inspection of pipelines and cables still need divers to complete.The reason is that underwater vehicles are highly susceptible to irregular undersea undercurrents when working in complex waters.The lack of research on hydrodynamic performance such as inability to effectively control their navigational state and working posture is an important factor limiting their development.Therefore,based on the research status of hydrodynamic performance of underwater vehicles at home and abroad,based on the actual working conditions,a micro-small low-speed underwater tracking vehicle is designed and carried out in complex flow field.Numerical simulation and experimental study of fluid dynamics to explore the key issues to solve the hydrodynamic performance of underwater vehicles in complex flow fields.Firstly,according to the requirements of the design task book,this paper determines the structural shape and size parameters of the underwater tracking vehicle,establishes a three-dimensional model in CREO,and completes the preliminary design.According to the actual working conditions of the underwater vehicle,the fluid dynamics control equation is established,and the corresponding turbulence model,numerical discrete method,numerical calculation method and physical model are selected.Secondly,numerical simulation of hydrodynamic performance of underwater propulsion is carried out.The ICEM is used to classify the studied watershed,and the corresponding turbulence model and boundary conditions are determined.The post-processing software Fluent is used to calculate the thruster model.Based on the simulation results,the relationship between the hydrodynamic performance of the underwater propeller and the installation position of the support plate is proposed.The influence of the number of the underwater propeller shield grid on the hydrodynamic performance of the propeller is studied.The underwater propeller is analyzed.The resistance in open water varies with different inflow velocity.The comparison shows that it is consistent with the trend in the reference literature.The feasibility of numerical simulation is verified.The variation of the surface pressure of the propeller in the flow field is studied.Considering the underwater propeller and the main body of the aircraft as a whole,and studying the unsteady interference between the two: when the flow velocity is constant,the different installation positions of the propeller on the main body of the aircraft are analyzed.The influence of hydrodynamic interference between the two;in the case of a certain flow velocity,the influence of the axial distance between the two on the thrust coefficient of the underwater propeller and the drag coefficient of the main body of the aircraft is studied.After that,the shape design and hydrodynamic characteristics of the underwater vehicle were studied.The ICEM is used to classify the studied watershed,and the corresponding turbulence model and boundary conditions are determined.Fluent is used to calculate the four underwater vehicle models without propellers and propellers at three different equilibrium positions..Based on the simulation results,the effects of the horizontal angle of attack and the horizontal rudder angle on the lift coefficient of the underwater vehicle in the four states are studied under the condition of constant flow velocity.The horizontal flow rate is determined under certain conditions.The influence of the angle of attack and the horizontal rudder angle on the pitching moment coefficient of the underwater vehicle in four states;comparing the flow field pressure cloud map and the flow field velocity cloud map in the four states,and summarizing the above simulation results,the thrust is obtained The best installation location.Then,the design study of each subsystem constituting the underwater vehicle is carried out.It is mainly composed of a power system,a control system,a weight system,a carrier frame,a sealed cabin and fins.Through the theoretical calculation,the exact position of the screw slider is obtained when the propeller is in three different installation positions,and the overall stability design of the aircraft is completed.Finally,the experimental prototype model of the underwater tracking vehicle was designed and manufactured.According to the requirements of the multi-degree-of-freedom movement of the experimental prototype,the power system and the weight system were partially designed to realize the underwater operation.Flexible.Hydrodynamic performance experiments were carried out on the experimental prototype of the following underwater vehicle in the numerical pool of the East China Sea Metrology Center of the State Oceanic Administration.Through the experimental results,the key points are analyzed: the speed of the incoming flow is constant,the change of the angle of attack of the aircraft,and the influence of the lift coefficient and the drag coefficient of the underwater tracking aircraft.Compared with the simulation results,the feasibility of the simulation results is verified.To sum up: the combination of computer simulation and prototype test is feasible for the hydrodynamic performance analysis of micro-small low-speed underwater tracking aircraft under different structural designs and motion states.The research in this paper provides a reference for the design and development of low-speed underwater tracking aircraft,and provides a new idea for the optimization design of subsequent high-mobility and low-speed underwater vehicles.