Study On Hydrodynamic Analysis And Manoeuvrability Of Disk-shaped Underwater Helicopter

With the gradual depletion of terrestrial resources and the growing need for growth in the development of human civilization,how to make full use of marine resources has become an urgent problem to be solved on the road of human survival,reproduction and development.Because the marine environment is complex and quite harsh,it is not suitable for direct human exploration.Therefore,Autonomous Underwater Vehicles(AUV)have received extensive attention in scientific research and military fields as an in-depth and effective means of marine exploration and development.However,the complex marine environment poses a great test for the safety and flexibility of AUV.Therefore,it is of great significance to develop a new type of AUV with better stability and maneuverability.This paper takes the new disc-shaped autonomous underwater vehicle as the research object,named the Underwater Helicopter.Underwater Helicopter is characterized by four functions:full-circle steering,fixed-point hovering,precise landing and free take-off and landing.In order to ensure the safety and flexibility of underwater helicopters working in the ocean,it is of great practical significance to accurately and quickly predict their hydrodynamic performance and motion.Firstly,based on the grid-independent analysis,the Computational Fluid Dynamics(CFD)method is used to calculate the friction coefficient of Underwater Helicopter at different speeds and compared with the mainstream calculation formulas at home and abroad.The numerical calculation of the hydrodynamic performance of the Underwater Helicopter is carried out.The resistance coefficients of the horizontal and vertical planes are obtained and compared with the experimental results of the towed pool,which verify the reliability' of the calculation in this paper.On this basis,three new Underwater Helicopter models with different aspect ratios are proposed,and their hydrodynamic performance is calculated numerically,which provides a reference for the design of a new generation of large Underwater Helicopters.Then,numerical simulation of the Plane Motion Mechanism(PMM)test for Underwater Helicopter is executed based on the overlapped grid technology of STAR-CCM+.The hydrodynamic coefficients of the Underwater Helicopter for the heave motion,sway motion,pitch motion,yaw motion and the roll motion are calculated.The viscous hydrodynamic coefficients,inertial hydrodynamic coefficients and second-order hydrodynamic coefficients are compared with the disk-shaped underwater vehicles developed by universities at home and abroad,which verifiy the rationality of the numerical calculation method of PMM test.The hydrodynamic performance of the Underwater Helicopter executing pure heaving motion and pitching motion in the non-uniform flow field is analyzed.Finally,from the numerical calculation results,Underwater Helicopter has the stability of horizontal and vertical plane motion,and it is verified by the pool experiment.The performance of the propeller of Underwater Helicopter is calculated.Combined with the hydrodynamic coefficient calculated by CFD in this paper,a six-degree-of-freedom motion simulation system is established based on the force analysis of the Underwater Helicopter.Simulation of straight ahead motion and spatial square diving motion are completed by MATLAB,analyzing the maneuverability of the Underwater Helicopter.The results lay the foundation for subsequent R&D design and control system optimization...