The Research On The Hydrodynamic Performance Of Propeller Boss Cap Fins Based On CFD Methods

These years, with the increase of the international oil price and the influence of economic crisis on international Ship Market, ship transportation and shipbuilding industry have been facing unprecedented challenges. In addition, because of the ever-increasing safety and environmental protection requirement which have been putting into effect by International Marine Organization (IMO) such as NOx emission, Tire II criterion ballast water treatment and The Goal Business Standard, the Energy Efficiency Design Index (EEDI) of new ships have been improved. Under such background, how to enhance the energy-saving efficiency under the precondition of original shipbuilding scheme becomes the primary task for design departments.As a new type of marine energy-saving device, if Propeller Boss Cap Fins (PBCF) could be placed after rudder reasonably the propulsive efficiency of propeller will be improved obviously. Therefore, the Computational Fluid Dynamics (CFD) method is applied in this paper to simulate the performance of PBCF.Firstly, in order to validate the accuracy of FLUENT software propeller DTMB4119is applied to prove the reliability of FLUENT depending on the results of comparison between computed results and experimental results. The corresponding PBCF shape will be designed on the basis of propeller DTMB4119. And then the energy-saving effect of PBCF will be investigated through changing the installation angle. From the results we could see that the PBCF could show its best performance in the installation angle of40degrees which could improve the efficiency by0.798%.Secondly, another special propeller is selected to consider the influence of PBCF on performance under the condition of multiple parameters which include installation angle, diameter and axial position of PBCF. According to the computed results we could achieve that the energy-saving effect of PBCF corresponding to the propeller is within0.52392%to1.14966%when the installation angle is50degrees and increases with fin blade diameter. However, there is no regular change for the influence of axial position on energy-saving effect. At last, the influences of propeller blade number, trim and different turbulence models on performance are simulated by using FLUENT in this paper. The results of these simulations show that the propeller referred in this paper could show a relatively better performance when the blade number is five and the propeller incline to prow. For the influence of turbulence model, however, the propeller efficiency of SST k-ω model we obtained is the best, RNG k-ε model comes second and Realizable k-ε model is the worst.Until now, there are not many literatures about PBCF to consult for us in China and in consequence the works in this paper may be able to provide some valuable numerical references for following research.