Structure Design And Hydrodynamic Analysis Of A Multistage Separable AUV

Autonomous underwater vehicle(AUV)is an important tool for exploring the ocean.It is widely used in marine scientific research,resource survey,intelligence monitoring,military support and other fields.The AUV performs tasks mainly relying on the corresponding functional loads.However,the conventional AUV has limited loading capacity and cannot complete the loads distribution.Therefore,this paper aims to study the design of a multi-stage separable autonomous underwater vehicle(MSAUV).It has multiple functional load cabins which connected by a separating mechanism at the top of MS-AUV body.The MS-AUV can carry the loads of the corresponding function according to the type of mission,and it can be deployed when sailing to the target sea area.It has high application value in the fields of ocean exploration and coastal defense.The main research work in this paper is as follows:(1)According to the function and index requirement of MS-AUV,the overall scheme design was made.The overall scheme,which provided the overall design ideas for system structure design and key technology research of MS-AUV,includes the working principle of MS-AUV,the overall structure layout,and the functions of each system module.(2)Firstly,the theoretical basis of hydrodynamic analysis of MS-AUV was established by computational fluid dynamics(CFD)method.Then,the main shape of MS-AUV and tail rudder were designed based on CFD method with the best comprehensive performance.Lastly,the overall shape of the MS-AUV was determined and hydrodynamic analysis was performed under different sailing attitudes and speeds.(3)The structural of the MS-AUV separation system,including functional load cabins and separation mechanisms,was designed.The function load cabins and the MS-AUV body adopt vacuum connection to realize multi-stage connection,which reduces the complexity of the separation mechanism and improves the stability and safety of the separation motion of the load cabins.In order to analyze the safety of load separation,the dynamic hybrid unstructured grid technique adapted to large-distance multi-body motion and the coupling method of CFD and six degrees of freedom(6-DOF)rigid body kinematics were used to simulate the separation motion under different water working conditions.Through the simulation calculation,load cabins motion trajectory and attitude parameters were obtained to verify the feasibility of the separation method.(4)Based on the design of the MS-AUV shape,the system structure was designed.Firstly,the pressure-resistant case and connection sealing structure of MS-AUV were designed,and the finite element analysis and compression test were carried out to verify the compression and watertight performance of the structure.Then,the design and analysis of the center of gravity adjustment mechanism and the tail rudder steering mechanism were carried out.Finally,the structure of the propulsion system of MSAUV was designed.The propeller was parameterized design by OpenProp and the main propulsion motor was selected.The propeller thrust performance was verified by CFD simulation based on MRF model and pool thrust test.It can meet the thrust demand of MS-AUV.(5)A marine test of the prototype of the MS-AUV body was conducted.Firstly,the offshore sea surface tracking function test was carried out.The experiment verified that the MS-AUV body prototype has good trajectory tracking performance,attitude maintaining ability,heading maintaining ability,power propulsion ability and fixed speed sailing ability.Then the performance of the navigation index was tested and the experimental results had reached the main design indicators.It laid the foundation for the subsequent multi-stage functional load cabins of the MS-AUV and further completion of the deep sea autonomous navigation test.