Modeling And Simulation Of Azimuth Stern Drive Tug In Regular Waves

With the increasingly enlargement of vessels,their maneuvering become more difficult in the harbor water.So port tugs which represent by azimuth stern drive tug play an important role in assisting vessels berthing,unberthing,and guaranteeing the safe production of harbor.The task of interactive tug simulator has advantages in training tug officer,pilot and other related personnel.Tug operation mathematical model is related to behavior reality of true simulator.And model accuracy is the important index of measuring tug simulator performance.Tug six degrees of freedom motion mathematical model can more accurately simulate the tug real motion,and promote the quality of the tug simulator.This thesis focuses on azimuth stern drive tug six degrees of freedom motion mathematical model in regular waves,and the main works of this thesis are summarized as follows.Firstly,based on predecessors’ research and the idea of MMG modeling,combined with the ship maneuvering and seakeeping,this thesis establishes azimuth stern drive tug six degrees of freedom motion mathematical model.Secondly,in view of the polymorphism of azimuth stern drive tug maneuverings,this thesis uses method by Yang Yansheng that applies to constant and low velocity field to calculate maneuverability hull hydrodynamic.In combination with tasai atlas,using STF method to calculate the hull hydrodynamic of ship heaving and pitching motion.Thirdly,based on Yoshimura method,this thesis uses the thrust coefficient of first quadrant to estimate the thrust coefficient of other quadrants,and establishes ducted propeller thrust model.Fourthly,treats tug as box-shaped ship approximately,based on the Froude-Krylov hypothesis,calculates the wave force and moment,and establishes the mathematical model of wave force and moment.Finally,this thesis establishes the simulation platform via Visual Studio2013,and carries out simulation experiments of tug Delta Linda in static and wave condition.The result results show that the tug motion mathematical model in regular wave can satisfy the actual engineering requirement,and have the certain actual application value.