The Sail Optimization And The Resistance Characteristic Research Of The Sail-assisted Ship

In recent years,the oil price is low,but it is non-renewable and the reserves is limited.Unlimited exploitation and using is very harmful to the economy sustainable development.Therefore the new type of ship must be developed to the direction of low fuel consumption,and at the same time reduce the adverse impact on the environment.The international maritime organization(IMO)and the European Union(EU)become more strictly to the regulation of ship emission.In this background,the concept of "green ship" arises at the historic moment,its core is to achieve energy conservation and emissions reduction.Using sails to auxiliary navigation of ships,is a typical way of new energy applied to the sailing.But most of the research is to the shape of the sails,the research to the resistance of the sail-assistant ship is very limited.So in this article,the research is based on the ship resistance prediction,using the numerical simulation software STAR-CCM +,to calculate the ship resistance under different wind angle and drift angle.And analysis the result,find out how to adjust the sail angle in order to obtain largest thrust under different wind angle,and summarize the influence of wind angle,drift angle and rudder angle to the ship resistance.The main research content of this paper can be summarized as follow:(1)The sail optimization and the research on the aerodynamic characteristics.Firstly,select the conventional airfoil NACA0012 as validation airfoil,using the overlap grid technology of software STAR-CCM+,to simulate the aerodynamic characteristics of airfoils.And compare the results with the test data to verify the feasibility of the numerical simulation method.Then select the target sail-elliptical arc sail,and change the arch camber ratio,thickness ratio and aspect ratio to calculate the thrust coefficient under different wind angle and different geometric angle of attack.To find out the best attack angle to obtain a large thrust.And compare the results to choose good parameters of the sail.(2)The resistance prediction of the target ship(45000 t bulk carrier)and the validation of CFD method.To forecast the ship resistance under different speed,using the VOF method to capture the free liquid surface,and to set the damping wave around the border.During the process of numerical simulation calculation to the ship resistance,using different turbulence model,different grid number and different encryption area.And compare the results with the ship model experiment data,to verify the feasibility of the simulation software and the reliability of the grid and condition setting.(3)The research on the ship resistance characteristic under different drift Angle.On the resistance prediction of straght driving under different wind angles,to simulate the two cases of decorating two sails and four sails,compare and analysis the interference between the sails,and find out the navigation efficiency under different wind angles and its changing rule.Then fix the wind angle,to research the ship resistance characteristic under different drift angle,and compare with the increasing resistance of empirical formula,summe up the resistance changing law with drift Angle.(4)Analyze the effect of rudder angle to the resistance performance of the ship.And reduce the drift angle produced by the sail to ensure straight driving through the adjustment of the rudder angle.To forecast the ship resistance under different wind angle and different rudder angle,analysis the stress of the rudder and its influence on the ship,then calculate the ship resistance and rotary torque under different wind angle and rudder angle.Find out the rudder angle when the rotational torque is zero(i.e.,zero drift angle),and analysis its resistance performance.