Hydrodynamic Performance Of Propeller In Wave

The ship is usually driven in a complex environment,the propeller is also running in the complex flow conditions including the oblique flow,wave,the propeller motion because of the hull and so on,so that the ship resistance increases,the propeller hydrodynamic performance is reduced,leading to the ship can not reach the design speed.Therefore,in order to accurately predict the ship's rapidity,it is necessary to accurately predict thehydrodynamic performance of the propeller in complex conditions.Based on these considerations,this paper uses the Computational Fluid Dynamics(CFD)software to simulate the force and moments on propeller in different conditions,including open water,oblique flow,static water surface and wave conditions,and other conditions close to the actual external environment.The results of the calculation in this paper can provide references for propeller performance prediction and ship rapidity forecasting.Based on the advantages of the structured grids,this paper first uses the ICEM to divide the DTMB4679 model into a structured grids.The open water performance of the propeller was calculated by Fluent,and the open water characteristic curve was obtained.The pressure distribution and the experimental value were compared,verify the correctness of the calculation results.The calculation of the steady open water characteristic of the propeller will lay the foundation for the unsteady calculation.The complex flow field around propeller would led to the propeller unsteady hydrodynamicperformance,propeller thrust and torque appear obvious time-domain characteristics.In order to investigate the unsteady hydrodynamic performance of the propeller,the complicated flow field around the propeller is simplified to uniform non-axial flow.The CFD software is used to calculate the force on blade at different positions of the propeller rotating at one cycle.The position of the peak and the valley of the propeller in different directions are obtained.At the same time,this paper analysis the hydrodynamic performance when the propeller in the oblique flow with differentoblique angle.It is found that the oblique angle has great influence on the propulsiveforce,and the position of the peak and trough in the different oblique angle is almost the same.Then,this paper analyes the effect of the water surface and wave conditions on the hydrodynamics at different shaft submergence depth.Here we used the Star-CCM + software.This software has some advantages over Fluent in some aspects.For example,in this paper,we need to re-divide the grid in ICEM.In Star-CCM,we only need to change the height of the boundary layer from the numerical value.This greatly saves the modeling time.During the calculation,we studied how the propeller performance changes when the propeller shaft is at different heights from the free liquid surface.It is found that when the height is greater than 1.2 times of the propeller diameter,the free surface has little effect on the propeller.When the propeller is approaching the free surface,the propeller thrust coefficient and torque coefficient are reduced.Finally,in order to accurately simulate the performance of the propeller in the real environment,this paper makes a model of hull-rudder-propeller,and calculates the influence of the rudder on propeller hydrodynamic performance.The flow field is analyzed.Stern wave in stationary liquid is obtainedand compared with that in waves.