Numerical Simulation Of Submarine Roll Control With Detached Rudder In Emergency Maneuvering Motion

Submarine plays an important role in the exploitation and utilization of ocean resources and the protection of maritime territorial sovereignty.With the increase of underwater speed and the need of emergency maneuvering,the submarine will be in a dangerous heeling condition when it is in a strong maneuvering movement.It is very important to study the motion response characteristics and navigation attitude control of submarine under strong maneuvering motion to ensure the safety of submarine.Previous researches on submarine attitude control were mostly based on simplified mathematical models,which were difficult to obtain sufficient flow field information.The large number of hydrodynamic coefficients are difficult to solve when considering strong nonlinear motions.The computational fluid dynamics(CFD)method solves the governing equations describing the fluid flow by computer,and then iteratively solves the equations by combining with the six-degree of freedom motion model of rigid body.The mathematical model is more realistic and can provide the detailed time-space information of the submarine and the fluid.Therefore,it has become a popular numerical prediction method for the maneuvering motion of the submarine.In this paper,the RANS method is used on the STAR-CCM+ platform.The fully attached SUBOFF submarine model is used as the research object.The method of overlapping mesh and sliding mesh are used to deal with the relative motion of the main body and rudder.The volume of fluid model is used to simplify the simulation of the propeller.Numerical simulation of two emergency maneuvering motions were carried out to study the influence of relevant motion parameters on the submarine’s motion trajectory and attitude.The field function was compiled to realize the automatic control of the tail detached rudder.Research has been carried out on the ability of roll control in strong maneuvering motion.Firstly,the numerical calculation of the flow field and the force(moment)of SUBOFF submarine at different speeds and attitude angles is carried out,which verifies the correctness of the calculation method.Then the influence of propeller,initial roll Angle,gravitybuoyancy ratio and other factors on surfacing motion of submarine is discussed,which lays a foundation for the research of the emergency surfacing motion of submarine under controlling factors.Then,a numerical study of the effect of the detached rudder on the roll control of the submarine during the emergency surfacing was carried out.Three initial roll angles(0°,15°and-15°)were selected as the calculation conditions,and the variation characteristics of the motion parameters such as the trajectory,roll angle and pitch angle were studied.The results show that the roll angle of the submarine decreases greatly under the control of the detached rudder,which is almost zero in some cases.The separate rudder has a good performance on the roll control of the submarine in the emergency surfacing motion with initial roll Angle.Finally,the numerical simulation of high-speed plane rotation motion and space high-speed rotation motion are carried out to study the effect of the detached rudder on the control of the submarine’s roll attitude.The problem of motion instability in submarine numerical simulation is successfully solved by applying extra torque.The results of numerical simulation of high-speed plane rotation and high-speed space rotation indicate that the detached rudder has a good performance on the roll control,which can suppress the roll fluctuation and greatly reduce the static roll Angle of the submarine during turning.The performance of roll control of space rotation motion is better than that of plane rotation motion.It should be noted that the torque generated by the detached rudder in other directions may influence the movement of submarine.