The Study For Parameters Of Two Common Energy Saving Devices

Since the reform and opening up,China has been experiencing rapid economic and social development.However,during the period,a huge energy consumption and low efficiency result in a large number of greenhouse gases,of which the shipping industry accounts for a large proportion.With the awareness of energy conservation and environmental protection enhanced,the concept of“green shipbuilding”has been widely recognized and respected.The development and implementation of the EEDI standard is an important measure of CO₂ energy efficiency by representing the environmental costs of the social benefits created by per unit of vessel transport volume.In order to balance the operating efficiency and environmental costs of ships,the innovation of ship design technology and application of energy saving technology come into being.Mainly including:optimizing the ship and reducing hull resistance;the development of efficient propulsion and new boost mode;optimizing the power plant and its supporting equipment;developing hydrodynamic energy saving device.Compared to other energy saving technologies for ships,energy saving devices have the advantages of low cost,significant energy saving effect and easy installation,more and more favored by the ship owner.There are some common energy saving devices including wake equalizing duct and pre-swirl duct.The effect of energy saving device for ships will be affected by its size parameter,but it costs too much to study the size parameters of energy saving device by using model test method.With the development of computer technology and the progress of numerical methods,the size parameters can be studied at low cost and high efficiency and the accurate pressure and wake field information can be presented.The work of the paper is based on the CFD solver naoe-FOAM-SJTU developed by Professor Wan’s team for solving hydrodynamic problem of ship and ocean engineering,in which the overset grids technology is used to calculate the total viscous flow field.In the paper,numerical calculations are carried out according to the 2015 Tokyo CFD Symposium and JBC（Japan Bulk Carrier）is used as the carrier to study the length,diameter of the inlet and outlet,and the pitch from the propeller of wake equalizing duct,as well as the length and numbers of stator of pre-swirl duct.The energy saving effect is evaluated by propulsion efficiency and output power of propeller.