Hydrodynamic Numerical Study Of Remotely Operated Underwater Vehicle And Ducted Thruster Based On Dynamic And Slip Mesh Grid Hybrid Technology

Using CFD methods,based on Hybrid technique of dynamic mesh and sliding mesh,mesh renewal method for spring smoothing and local mesh reconstruction,solve the N-S equation in the watershed where the underwater robot system is located.Study the hydrodynamic characteristics of the underwater robot system under different motion states and the thrust characteristics of each position propeller.Comparison of numerical simulation results and experimental results shows that,it is feasible to study the hydrodynamic characteristics by using the dynamic mesh and sliding mesh hybrid technology,the numerical solution is a reflection of the real hydrodynamic change law and the trend of the underwater robot system to a certain extent.it can be used as a model test supplement.In different modes of motion,the propeller disk surface feel the water flow rate is different,so that the propeller blade section hydrodynamic pitch angle is different,resulting in the propeller produced different axial induction velocity,making the ducted propeller issued different thrust.The greater of the water velocity,the smaller of the hydrodynamic pitch angle,the smaller the axial induction speed of the propeller,the smaller of the thrust.On the contrary,the greater.Under different motion's of the underwater robot system,the main body has a significant effect on the surrounding flow field.In the reverse movement,the propeller reverses,due to the main body of the blocking effect and external expansion,the rear propeller,left propeller and right propeller's thrust greater than the single propeller.In the forward movement,the propeller forward rotation,a negative entrainment is formed on both sides of the main body so that the thrust of the propeller on both sides is reduced.The main body's blocking effect on the water,causing the rear area of the water flow slowed,so that the rear propeller thrust increased.In the deep motion,two-dimensional linear motion,two-dimensional circular motion,three-dimensional circular motion,the robot body has a significant effect on the thrust characteristics of the ducted propeller.Based on the six-degree-of-freedom solver provided by Fluent,using dynamic mesh technology to study the motion characteristics of the underwater robot system under the influence of current and different external forces.The numerical results show that,the instability of the underwater robot increases gradually with the increase of the current velocity,and there will be a significant yaw in the later stages of the movement,and the yawing distance occurs with the increase of the current velocity.With the increase of thrust,the curvature of the displacement trajectory curve is gradually reduced and the curve is graduallytransformed into a straight line.The stability of the underwater robot movement under the influence of forward current is significantly higher than that of the reverse current.