Calculation And Analysis Of Ship Added Resistance Based On Taylor Expension Boundary Element Method

With the development trend of green ships and safe ships,the IMO(International Maritime Organization)has successively proposed the EEDI(Energy Efficient Design Index)and the minimum propulsion power guideline.The former stalling factor fw has a direct impact on the ship's EEDI accounting;the latter requires the ship to ensure a certain speed in the waves.Ship added resistance is one of the main factors that affect the stall coefficient;on the other hand,it is an important part of approving the minimum propulsion power of ships.For this reason,this paper studies the calculation method of added resistance based on Taylor expansion boundary element method.First of all,it gives the problem of fixed solution under the condition of speeding waves.In this paper,the matching technique is used in TEBEM.The outer domain uses the time-domain Green's function to propagate the waves smoothly.The inner domain uses the Taylor expansion method to solve the non-smooth ship boundary velocity and its derivatives more accurately.After the solution of the velocity potential and its derivative,the first-order force is integrated on the hull surface by the Bernoulli equation,and then the fourth-order Runge-Kutta integral is used to solve the ship's heave and pitch motion.Finally,Use Bernoulli integral to get the second-order average drift,which is the required added resistance.Second,KCS container ship and KVLCC2 oil tanker are used as examples to verify the numerical method of TEBEM method.The calculated results are compared with the experimental data and other numerical methods to prove that this method is effective to solve the motion and added resistance.The added resistance contribution of the various parts is compared in the ships.Thirdly,using the TEBEM method,three representative ships,the mast KVLCC2,the KCS and the S175,were calculated.The parameters used in the calculation process are divided into spatial discrete parameters,discrete time parameters and free-surface conditional assumptions,and each of them is independently calculated and analyzed.Finally,a group of generalized dimensionless parameters with both computational accuracy and computational efficiency are obtained.After taking this set of dimensionless parameters,the disaggregation of each added resistance component of the two vessels was compared to verify the validity of the set of dimensionless parameters.Fourthly,after the above dimensionless parameters are fixed,three model ships: Wigley ship,Series 60 ship with a square coefficient of 0.7and DTC ship are solved,and the calculation results are compared with other numerical methods and experimental values.It is proved that this method of fixing dimensionless discrete parameters is practical and effective for solving added resistance problem.Fifthly,comparing the calculation results of TEBEM with those of CFD,Japan empirical formula and STF/semi-empiric formula shows that TEBEM has well calculation accuracy under the premise of meeting the engineering calculation time requirements.