Study On Hydrodynamic Analysis And Maneuvering Performance Of Disc-shaped Underwater Vehicle

With land resources,energy and space running out,the exploitation and development of oceans has become a priority.But marine environment is complex,volatile and harsh,human beings cannot directly submerge to carry out operations.The development tools with high performance are needed for further exploration.Therefore,developing a small underwater vehicle with wide application range,flexible mobility and comprehensive functions has become a key research direction.In this paper a disc-shaped underwater vehicle for environment monitoring is designed.To ensure motion stability and maneuverability of the disc-shaped underwater vehicle in working environment,it is important to research on hydrodynamic performance and maneuverability.First of all,structure design of the disc-shaped underwater vehicle is completed,and its three-dimensional model is constructed.In addition,the coordinate system is established and dynamic parameters of the vehicle are defined.The corresponding coordinate transformation matrix is derived.On this basis,motion modeling of the disc-shaped underwater vehicle is carried out.The six-degree-of-freedom spatial motion equation is established,which provides the basis for subsequent hydrodynamic analysis and maneuvering performance research.Then,steady hydrodynamic performance of the disc-shaped underwater vehicle is analyzed.Motion resistances of the disc-shaped underwater vehicle are numerically calculated to obtain drag coefficients in horizontal and vertical plane at different velocities.Hydrodynamic performance of the disc-shaped and traditional spheroid underwater vehicle in oblique navigation is compared and analyzed.The calculation results show that the disc-shaped underwater vehicle can obtain greater lift force and less transverse force than the spheroid underwater vehicle under the same motion conditions.It's proved that the disc-shaped underwater vehicle has better hydrodynamic performance.Moreover,in order to obtain hydrodynamic coefficient of the disc-shaped underwater vehicle,the unsteady hydrodynamic numerical calculation is carried out.The elastic smoothing method dynamic mesh technique is used to simulate the test of planar motion mechanism.The changes of forces and moments under different movement posture will be obtained.Hydrodynamic coefficients of the disc-shaped underwater vehicle are obtained by the experimental data fitting.Subsequently,the dimensionless processing hydrodynamic coefficients are compared with the other published disc-shaped underwater vehicle.It can be seen that the hydrodynamic coefficients solved conforms to calculation law,and the overall order of magnitudes and symbols are basically same,which proves reliability of the calculation method and accuracy of the results.Finally,through the numerical calculation results,maneuverability of the disc-shaped underwater vehicle is predicted from two aspects of stability and mobility.Based on the Routh algebraic stability criterion composed of first-order linear hydrodynamic coefficients,motion stability of the disc-shaped underwater vehicle is analyzed.In the horizontal and vertical plane,the numerical calculation is carried out by using two different turbulence models,and the stability coefficients are in accordance with the criteria.The calculation results show that the motion of disc-shaped underwater vehicle in horizontal and vertical plane is stable.In the study of mobility,space spiral motion and horizontal bow-steering test are used to analyse the navigation state change characteristics of the disc-shaped underwater vehicle.The results show that the bow-steering is rapid,flexible and maneuverable.Maneuverability prediction and comprehensive evaluation of the disc-shaped underwater vehicle are completed,which lays a foundation for subsequent optimization design and development of control system.