Experimental and computational study of hull–propeller–rudder interaction for steady turning circles

Abstract

The hull–propeller–rudder interaction of the Korea Research Institute of Ships & Ocean Engineering Container Ship is studied using a combined experimental fluid dynamic (EFD) and computational fluid dynamics (CFD) method with an innovative approach employed for the analysis of steady state circular motions. The force and moment balances are analyzed by decomposing into contributions from the bare hull, rudder, and propulsor. Detailed investigation of the computed local flow fields is performed including the hull vortices, surface pressure and streamlines, and propeller and rudder inflows. The force and moment balances mostly have a similar trend for both the EFD and CFD. The propeller inflow in port and starboard turning shows different trends, and the propeller is more heavily loaded with reduced efficiency as compared to the straight-ahead condition. The port side shows larger magnitudes of the hull vortices, more propeller load, lower propeller efficiency, larger drift angle, and smaller circle radius than the starboard side turning. These differences are explained via the hull–propeller–rudder force and moment balances with the aid of transformed circular motion equations of centrifugal force. The surge (X) force is hardly changed, but the lateral (Y) force is reduced (largely due to the rudder force) for the port side turning, which induces a larger drift angle and more speed loss. The overall conclusion is that the circular motion induces the centrifugal force and drift angle, which induce the hull vortices, off-design propeller inflow, reduced propeller efficiency, increased propeller thrust, and speed loss in addition to the propeller rudder interactions.