Hydrodynamic Derivatives And Maneuverability Prediction Of The Deep Towed System's Mother Ship

Maneuverability is one of the important hydrodynamic properties of a ship.The development trend of modern ships is high-speed,large-scale,and specialized and ship maneuverability becomes more and more important.In recent years,with the development of computer computing power and CFD technology,the accuracy of numerical forecasting has been continuously improved,and the application scenarios of CFD numerical simulation are gradually expanding.In terms of ship maneuverability,the CFD numerical simulation method has been exposed.The International Towing Tank Conference(ITTC)Maneuvering Technical Committee held academic seminars in 2008 and 2014 respectively to organize comparative studies on the verification and validation of numerical simulation methods for various maneuverability forecasts.CFD method and the test method are used to numerically study the hydrodynamic derivative and maneuverability of ships.At present,the most common method for predicting ship maneuverability is to determine the hydrodynamic derivative of the ship and using mathematical model of the maneuvering motion of the ship to carry out numerical simulation prediction.Based on CFD technology,this paper explored the method of grid division and the selection method of turbulence model.The overset grid technique was used to numerically simulate the restraint ship model test such as the oblique flight test,pure sway test and pure yaw test.The multi-functional circulating water tank of Shanghai Jiao Tong University carried out the restraint ship model test of the same working condition.Compared with the numerical calculation results,the reliability of the numerical simulation method was verified.Based on python programming processing data,the relevant hydrodynamic derivatives are determined,which shows the feasibility of numerical simulation method to calculate the hydrodynamic derivative of ships.By comparing the hydrodynamic derivatives of the notch closure and opening,it was found that the existence of the notch increased most of the hydrodynamic derivatives.The ship's turning test and zigzag test were simulated based on the MMG ship maneuvering equation.Firstly,in order to verify the reliability of the method,the mathematical model of the ship maneuvering motion was constructed by using Matlab using the relevant hydrodynamic derivative of the standard ship model KVLCC2.The ship turning test and the zigzag test were predicted.Compared with the test values,the two movements were consistent.The trajectory coincides with the diameter of the revolution,which verifies that the method is feasible to predict the maneuverability of the ship.On this basis,the fourth-order Runge-Kutta method was used to solve the MMG mathematical model in the matlab environment.The simulation of the ship's maneuvering motion was completed.The trajectory of the ship's maneuvering motion was obtained and the turning diameter and the turning cycle were obtained.This shows that the calculation method used is an effective method to accurately predict the maneuverability of the ship.By comparing the maneuverability of the ship during the close and open of the notch,it is found that the existence of the notch will weaken the ship's rotation performance and the heading stability becomes stronger.In this paper,the CFD technique was used to numerically simulate the restraint ship model test.The maneuvering motion of the ship was simulated by Matlab programming based on the MMG equation.Comparing with the experimental value,it can be found that the maneuverability forecasting method adopted in this paper has strong practicability and high calculation accuracy,which can meet the forecasting requirements of ship maneuverability in the initial stage of ship design,and has certain engineering application value.It provides a feasible solution for numerical prediction of ship maneuvering motion and promotes the application of CFD technology in ship maneuverability.