The EFD and CFD Study of Rudder-Bulb-Fin System in Ship and Propeller Wake Field of KVLCC2Tanker in Calm Water

摘要

Developing the high efficiency ships is one of the goals that we areheading. The present work is to study the energy saving device, whichis a rudder-bulb-fin system, designed for the KVLCC2 tanker. Thehorizontal fins on the both sides of the rudder bulb share the same foilsection, but the suction side faces up on the portside and faces downon the starboard side. The concept is to recover or reduce the energyloss, or gain extra thrust in the propeller rotational flow. The viscousflow simulation was performed by CFDSHIP-IOWA V4.5 with apropeller model. The test condition is at design Froude number 0.142in calm water for a 3.2m long ship model. The force and flow fieldwere measured in Osaka University towing tank. The propellerrotational rate was determined in EFD (Experimental Fluid Dynamic)self-propulsion test. EFD and CFD (Computational Fluid Dynamic)showed good agreement for rudder flow field and forces for zerodegree AOA (angle of attack) for both fins. Furthermore, the AOAcombinations from 1 to -2 degree with 1-degree increment for both finswere investigated by CFD only. The best energy saving effect AOAwas found; 0 degree for portside fin and -1 degree for starboard sidefin. The total resistance was reduced by 2.3% compared with thenormal rudder case. Among the cases, its thrust deduction, effectivewake and hull efficiency factor were the optimal values.