Numerical Simulation And Analysis Of Ship Self-propelled With Energy-saving Device-propeller-rudder

With the energy shortage,rising oil prices,greenhouse effects and other issues in the last decades,energy-saving emission reduction increasingly aroused the concern of the community.Shipping industry consumes a lot of energy and emissions and of large amounts of greenhouse gases,so the ship energy saving has become an important research topic in the world's shipbuilding industry and shipping sector.In recent years,the International Maritime Organization(IMO)has accelerated the implementation of green shipbuilding,limit the pace of new shipbuilding greenhouse gas emissions,and promote the development and implementation of ship energy efficiency design index(EEDI)standards.The EEDI was established to build a minimum energy efficiency standard for the ship and stimulate all innovations and technological developments that affect the energy efficiency of the ship from the design stage.At the same time,the continuing downturn in the shipping industry has sparked a strong demand from shipowners for reducing ship energy consumption.By virtue of its simple process,low risk,the obvious effect and a wide range of applications,ship energy-saving devices has become more and more popular in shipping market.At present,the study of ship energy-saving devices is mainly based on the method of model test.However,the design of ship energy-saving devices requires accurate assessment of the flow field,so a lot of detail design and modification is needed,which led to the full use of model tests for ship energy-saving device design costly.With the development of numerical techniques and the progress of computer hardware,computational fluid dynamics(CFD)is playing an increasingly important role in many disciplines,including ship degign and ocean engineering.By using the CFD technique to calculate the total viscous flow field,we can accurately capture the information of the stern detail flow field and evaluate the effect of the energy saving device effectively.The work of this paper is based on the solver naoe-FOAM-SJTU,a hydrodynamic CFD solver developed by the research group,which uses the overlapped grid technology to calculate the total viscous flow field.In order to evaluate the self-propelled feature of VLCC and JBC fitted with energy-saving devices,the calculation of standard ship JBC from Tokyo CFD Seminar in 2015 is carried out firstly,the reliability of the solver and the overlapping grid technique is verified by comparative analysis of the experiments.Self-propulsion simulations in this work consider the effect of free surface and directly discretized propeller.Self-propulsion points are obtained in a single computation by using a controller to modify the propeller RPS until the target speed is reached.Finally,self-propulsion factors for self-propelled JBC and VLCC with and without ESD(Energy Saving Device)are analyzed and compared with experimental data.