Hydrodynamic optimization of performance of blunt ships

Abstract

Abstract Various research works on hydrodynamic performance of the general streamlined ships in the domain of ship fluid mechanics have been implemented during the past several decades. However, as to those special types of ship, say, the blunt ship, relevant investigative work is never put on the top of the agenda. This paper and the subsequent work would like to deal with a representative kind of blunt ship, the dumb barge. It is expected that the research work can supply a gap in the weakness of study on the blunt ships. The drags and flow fields of the dumb barge models are numerically calculated by solving the RANS (Reynolds Averaged Navier-Stokes) equations associated with the RNG (ReNorma- lization Group) k-ɛ turbulence model and the VOF (Volume Of Fluid) model. The comparisons of the calculated drags with that of experimental data from towing tank shows that hydrodynamic performance of the dumb barge can accurately be predicted by numerical calculations. On the basis of the aforementioned numerical calculations, the work turns to the hydrodynamic stability of the barge. Theoretically speaking, the faster the barge moves on the water surface, the greater the trim angle. This means the barge would lose its hydrodynamic stability when it goes faster and faster. To overcome this difficulty, it occurs to us that the hydrodynamic stability of the barge at high speed may be improved by some appendages on the hull. Then two experiments are carried out, respectively, for two styles of hydrofoils with the same profile. The first twin hydrofoils are symmetrically put on the two sides of the hull and the second single hydrofoil below the bottom of the hull. At a series of steady speeds of the barge, every group of experiments includes two aspects of information, the drags and the trim angles. The experimental results indicate that the hydrofoils effectively control the flow fields around the appendaged barges.