Impact of bulbous bow shapes on hydrodynamic derivatives due to hybrid drifting and circular motion tests

Abstract

Bulbous bows have been applied on a large variety of low-speed blunt ships to reduce wave-breaking resistance. However, the impact of bulbous bow shapes on the maneuverability remains unsolved. Three scaled SCb-87 series ships with different bulbous bow shapes, from protruding bow to vertical stem, are studied. Forces and moments of the bare hulls at drifting, circular motion, and hybrid conditions are obtained from Computational Fluid Dynamics simulations. The double-body and moving reference frame methods are utilized to obtain the resistance characteristics, vorticity, and flow field distribution with service speed (Fr = 0.142). The meeting of turning and zig-zag criteria is discussed to demonstrate the hydrodynamic performance and maneuverability of the three ships. Simulation results show good consistency with experimental results, and it is concluded that, under low speed and calm water conditions, the variation bulbous bow shapes from the protruding bow to the vertical stem have no obvious effect on both the hydrodynamic performance and ship turning and continuous steerage performances, the minor difference is caused by the extension of waterline length and the increased underwater lateral area. Further research is needed to make clear the influence of bulbous bow shapes on the maneuverability under medium- and high- speed conditions.