Study On Ship Powering Performance Prediction Based On Virtual Experimental Tank Of RANS Method

In ship hydrodynamic field,powering performance is an important performance index of ships.The powering performance of ships has a direct influence on the operating cost of merchant ship,as well as the battle effectiveness and survivability of warship.To satisfy the need of human on exploiting marine resources,future shipping industry and naval battles,a higher demand is put forward on powering performance of military and civil ships.Therefore,it's very important to find an effective and accurate method to predict the powering performance of ships.The powering performance of ships contains two aspects,which are resistance performance and propulsion performance.Ship model experiment method and theoretical method based on potential flow are the two main prediction methods of resistance and propulsion performance.As the computer technology and numerical simulation method develop rapidly nowadays,by solving the Reynolds averaged N-S equation,viscosity RANS method is widely used in the hydrodynamic performance evaluation of ships.It forms a well mutual complement with model experiment,and offsets the limit of potential theory on ignoring the influence of viscosity on hull flow field.The EU started a virtual experimental tank project in 2004,and put forward a comprehensive hydrodynamic performance virtual experimental strategy of ships to accelerate the progress of virtual experimental tank technology of RANS method.At present stage,the study at home and abroad on powering performance prediction of ship RANS method based on virtual experimental tank technology has achieved innovative achievements.However,there is still a big gap between the application research of virtual experimental tank technology with the long-term goal of the ship RANS method.So it's necessary to establish more numerical calculation methods to develop and perfect the application research of virtual experimental tank technology.This paper,based on the virtual experimental tank technology of ship RANS method,systematically establishes a numerical simulation method,which can be used to solve complicated hydrodynamic problem,such as total resistance and wave making resistance of hull,hydrodynamic of combined propulsion device and full-scale power and speed under the interactive interference between ship,propeller and rudder.On this basis,systematic numerical verification is made.(1)In order to complete the ship RANS method on prediction of hull resistance performance and promote the practicality of ship RANS method,this paper carries out some researches on the basic size of mesh,the first mesh height of boundary layer,the applicability of turbulence model and the uncertainty analysis of hull resistance.A set of meshing method on the prediction of resistance performance of conventional ship types is established.The better turbulence model is chosen to predict the hull resistance performance.(2)Based on the prediction accuracy of resistance performance of RANS method,this paper constructs virtual experimental tank to put forward an engineering computational method,which is based on three dimensional RANS to determine shape factor and solve the wave making resistance of hull.This method considers the mutual influence between viscosity and wave making,and breaks through the limitation of the inflow velocity,unstable flow and wave disturbance in determining the shape factor 1+K based on EFD method.At the same time,in order to compare it with the computational results of wave making resistance based on potential flow theory,numerical computational program for wave making resistance of Rankine source method is developed.The prediction accuracy and practicability of three dimensional RANS method and Rankine source method for wave making resistance of hull in this paper are validated through the computing of two practical ship types.The results show that three dimensional RANS method is better than linearized free surface condition Rankine source method.(3)In order to identify prediction reliability and accuracy of hydrodynamic performance of ship propulsion device,this paper constructs virtual experimental tank based on RANS method to carry out analysis on the practicability of turbulence model and uncertainty of ship propulsion performance,so as to build the foundation for the hydrodynamic performance prediction of combined propulsion device.(4)RANS method is adopted to carry out the prediction research on the selection of parameters for combined propulsion device hydrodynamic performance.This paper constructs virtual experimental tank to analyse propeller boss cap fins,tandem propeller and counter-rotating propeller,proper hydrodynamic performance parameters of combined propulsion device can be obtained.Numerical wake field is analyzed to study mechanism of action of combined propulsion device hydrodynamic performance.It can provide a reference for the application in engineering,as well as offer an important method on the choosing of hydrodynamic performance parameters of combined propulsion device.(5)A study on the powering performance prediction under the interactive interference between ship,propeller and rudder is made.This paper constructs virtual experimental tank to put forward a prediction method,which is based on two dimensional RANS to solve the power and speed prediction of full-scale ship.The accuracy and practicability of two dimensional RANS method in this paper on the power and speed prediction of full-scale ship are validated through practical ship type.And the flow field information changing is analyzed to study the mechanism of action of powering performance under interactive interference between ship,propeller and rudder.In summary,this paper establishes a virtual experimental platform based on above researches and systematically carries out numerical simulations and verification analysis.Meanwhile,it provides a reliable numerical computational method and practicable simulation technology for the prediction of ship powering performance which is basesd on virtual experimental tank of RANS method.