Informatics Publishing Limited

R. D. B. Prasada Naidu Dabbi , O. P. Sha

Abstract

The International Maritime Organisation has already made Energy Efficiency Design Index (EEDI) as a design norm which requires looking at design from energy consumption point of view. The study of the flow in and around the stern region of a ship needs greater attention. This is because of the fact that, the flow in the stern region defines the performance of the propeller. A highly uneven flow at the stern may lead to cavitations, vibrations and decrease in the propulsive efficiency of the vehicle. Recent advances in computational fluid dynamics techniques and development of Reynolds-averaged Navier-Stokes equations based methods have enabled a reasonably accurate estimation of resistance and facilitated the design evaluation of aft-body form and appendages that are highly influenced by viscous effects. By integrating CAD and CFD techniques along with databases of model tests, it is possible to explore and develop efficient hull forms within specified time constraints.

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Avinashm Godey , S. C. Misra , O. P. Sha

Abstract

Shipping transfers approximately 3 to 5 billion tonnes of ballast water internationally each year. Ballast water discharges non-native species leading to severe ecological problems. The present work aims at a design solution into the ballastless ship in which ballast water exchange and treatment is avoided by providing flow-through longitudinal pipes in the double bottom instead of conventional ballast tanks. During the design of the ballastless ship, different hull forms are generated with altering the hull shape in forward and aft out of which one was finalised. In addition to change in hull form the internal tank arrangement has been changed so that the propeller immersion and the minimum draft required in the ballast condition is achieved. Structural arrangement for the midship section was proposed for the modified hull form of ballast less ship as well as data on valves had been collected for the flow through condition. Finally, resistance tests were conducted on equivalent models of scale ratio 1:71 for the conventional and the proposed ballsatless form at the loaded and ballast drafts in the Hydrodynamic Towing Tank of the Department of Ocean Engineering and Naval Architecture, IIT Kharagpur. The model experiments on ballastless ship show an increase in resistance in ballast draft when compared to a conventional tanker due to the flow through pipes in double bottom.

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