Hydrodynamic Characteristics Analysis Of Underwater Vehicle Planar Maneuvering Motion

As an important form of underwater structures,autonomous underwater vehicle(AUV)have a wide range of applications in defense and military fields,scientific research fields and civil economy.In the initial stage of hydrodynamic performance design of underwater structures,the traditional design method,based on the System-based simplified mathematical model and through model experiments and Hydrodynamic Derivatives regression can be completed to predict the maneuverability of underwater structures.This method is simple and fast,but it requires high accuracy of the mathematical model of the structure and cannot analyze the flow field near the submersible in detail.With the development and improvement of Computational Fluid Dynamics based(CFD)technology,new ideas are available for maneuverability prediction analysis.This paper is based on the STAR CCM+ platform and Reynolds time averaging method(RANS)to study the direct numerical simulation of maneuvering motion of fully attached SUBOFF submarine model.The real model of the submarine and the real model of the matching propulsion equipment are used to simulate the motion in the flow field.The difference with the traditional overlapping mesh method is that this paper combines the advantages of computational speed and accuracy of the rotational motion of the sliding mesh,and simulates the self-shipping motion,two-dimensional free rotation motion and horizontal plane overtaking motion of the submarine through the mesh partitioning strategy.The paper firstly,the model resistance of the standard model of submarine at different speeds is numerically simulated and compared with the model resistance of the EFD results of other foreign scholars to verify the accuracy of the selected physical model and the numerical discretization method,and the motion of the DTMB4679 model propeller matched with the submarine is simulated using the overlapping mesh method and the slip mesh method,respectively,while the EFD results of other scholars A comparative study is conducted to discuss the hydrodynamic characteristics and accuracy magnitude of the two meshing methods in dealing with the propeller motion.Then the self-propulsion motions of the submarine at different rotational speeds of the propeller(500RPM,600 RPM,700RPM)are simulated and the self-propulsion points are obtained using the full overlap mesh method and the slip overlap hybrid mesh method under the mesh partitioning strategy,respectively.Then the two-dimensional planar slewing motion under different rudder angles(10°,15°,20°)is simulated numerically to study the slewing motion characteristics and computational efficiency of the structure under two different grid strategies.Finally,based on the grid partitioning strategy,two different rudder submarine models of cross type and H type are simulated for the overturning motion,and the bowing,following and rocking reduction performance of the two different rudder models in the overturning motion are quantitatively analyzed,and the simple flat H type rudder model is optimized and improved based on this starting point.The results show that the direct numerical simulation based on the grid partitioning strategy is consistent with the overlapping grid method in terms of computational accuracy and has a significant improvement in computational speed with the same grid size.The H-shaped rudder model has a slight loss in rudder performance but a significant improvement in rocking reduction performance compared with the cross-shaped rudder model during the overrunning motion,and the optimal wing width solution for the simple flat plate is50% of the parallel midbody diameter.