Research On Hydrodynamic Performance With Four Propellers And Double Rudders In Different Work Condition And Maneuverability Of Ship

Recently, in order to continuously improve the precision of maneuverability prediction, hydrodynamic performances of ship maneuverability are actively researched by many countries to accomplish ship maneuvering simulation in deed. Calculation of ship hydrodynamic performances is very important in accurate prediction of ship maneuverability.In this paper, propeller hydrodynamic performance in open water is calculated by FLUENT software. Thrust coefficient K_t and torque coefficient K_q can be calculated in different advance coefficient. Comparing with calculation data experiment data, it indicates CFD simulation on propeller hydrodynamic performance in open water is feasible.FLUENT and kaermakefu method are used to calculate the hydrodynamic performance of locked propeller in open water respectively.Resistance distribution and transverse force distribution are calculated in different advance coefficient when propeller is locked. Hydrodynamic performance of free rotational propeller in open water is also calculated according to the stable equilibrium theory of rigid rotation.The resistance and critical speed of rotation of propeller in different speed of advance is calculated. It indicates from computational result that speed of rotation in critical condition continuously increases according to the increase of advance coefficient.And in this way, critical transverse force gradually increases as resistance. The rotation direction of free rotational propeller is in accordance with propeller of normal working.Several conditions such as inward or outward propeller is locked and inward or outward propeller freely rotates in which wake effect of ship is considered are simulated, and propeller force is also calculated.Standard K-εturbulent model is used to calculate viscous fluid with free surface in this thesis. Ship resistance in different velocity is calculated. Comparing with experimental result, it is found that the resistance of calculation is less than test result at low velocity, it is opposite at high velocity. After all, the difference is very small and can be negligible. Calculating resistance curve and resistance curve of experiment fit very well. So it can greatly reflect resistance distribution which can testify that it is feasible to calculate viscous flow with CFD method.The wake distribution around ship is further calculated with CFD method including disk of inward propeller and outward propeller.Three dimensional velocity ratio distribution of hull and ship with appendages according to angle is calculated. The radius distribution of average axial velocity, average tangential velocity and average radial velocity is also calculated by CFD method.Average axial velocity, average tangential velocity and average radial velocity of propeller disk at different Fr number are also calculated. It is found that Average axial velocity on the disk of inward propeller and outward propeller increases respectively. It indicates that vary of ship velocity will affect distribution of ship wake.When building up mathematical model, the following factors have been considered: the forces and moment acted on ship, propeller, rudder and interaction between them. Hydrodynamic values which calculated by CFD are set to MMG equation. Runge-kutta method is used to calculate this equation to accomplish ship maneuvering simulation.The results of this thesis can provide the reference guides to study on rapidity and maneuverability of large-scale ship.