Ship Speed Prediction In Waves Based On Taylor Expansion Boundary Element Method

In order to accurately assess the energy efficiency level of ships to meet the energy efficiency requirements of the International Maritime Organization,this paper will use the Taylor Expansion Boundary Element Method(TEBEM)to calculate the performance of the propeller and the hull resistance,and predict the speed and power of the ship.Based on the results,the appropriate ship engine can be selected.The constant panel method based on the mixed distribution of source pairs is used as a traditional numerical method for propeller open-water performance prediction,which is used to compare with zero-order and first-order Taylor expansion boundary element methods.The constant panel method is used to predict the performance of the hydrofoil,and the tip vortex model is established to improve the calculation accuracy.When predicting the steady hydrodynamic performance of the propeller,the grid convergence of DTMB4119 and KP458 propellers is analyzed first,then the open-water performance and pressure distribution are predicted.The numerical results obtained by the zero-order and first-order Taylor expansion boundary element method are in good agreement with the experimental values.In the steady wave-making problem,the total velocity potential is decomposed into double-body potential and perturbation potential,and the boundary value problems are constructed and solved separately.A body-fitted grid is used on the free surface,and the third-order upstream difference method is used to process the high-order derivative of the perturbation potential in the free surface condition into the first-order derivative.Using Wigley,S60 and KCS as models,the wave-making resistance,sinkage and trim are predicted;The empirical formula is used to estimate the mutual influence between ship and propeller,and the equations are established according to the force balance to obtain the ship speed.The prediction of the speed in the wave needs to take the added resistance into consideration.First,the seakeeping performance of the standard ship model is predicted.As a result,the added resistance in irregular waves is calculated according to the wave spectrum.Obtaining the ship speed in the waves by iterative method,and calculating the delivered power according to the propulsion efficiency,has certain engineering practical value.The prediction results of the KVLCC2 in model scale are compared with the experimental results.The prediction results of full scale model are also compared with the references.