Research On The Hydrodynamic Performance Of Rudder With Bulb-Thrust Fins Combination

Recently, with the increase of ocean-going ship and the severity of international energy situation, the research on the ship energy saving is getting more and more crucial. Therefore, to recover the losing energy, which is taken away by the trail flow, is one of the important respects in the ship energy saving field. In this thesis, there is a research on the rudder bulb with thrust fins, which is a kind of easily fitted and low-investment hydrodynamic energy-saving assembly device. The hydrodynamic performance of propeller-rudder-rudder bulb with thrust fins system was calculated by using the methods of CFD software FLUENT, FORTRAN AUTO CAD and TECPLOT. The main contents are as followed:In the CFD software FLUENT, using RNG k-εformula turbulence model and combined with Moving Reference Frame model to calculated the propeller's steady hydrodynamic performance. The thrust and torque coefficient at different coming velocity coefficient are calculated, thus the relevant open water characteristic curve are rendered. And comparing with experience results, good reliability is testified for theoretic calculation mentioned in this paper. The pressure distribution of one blade and velocity distribution of propeller plane in the high and low velocity are analyzed.Adopting Moving Mesh Model in the CFD software FLUENT, calculated the unsteady hydrodynamic performance of propeller and rudder. Analysis the thrust and torque'change in one periodical time of the propeller and rudder. The velocity field of propeller and rudder system was studied at the same time.Based on the above calculation, the rudder bulb and the rudder bulb with thrust fins were added to the computation of the hydrodynamic performance. Thrust and torque of propeller-rudder-bulb system and propeller-rudder-bulb-fins system were calculated. The energy-saving effects of two systems were presented. Meanwhile, thrust fin's profile airfoil and installation angle that affect additional thrust efficiency were changed dimensions. NACA0012, NACA0015 and CLARK-Y that three airfoil and 0 degree,2 degree,4 degree that three installation angles were selected and discussed their influence on the energy saving result.