Calm water resistance and self propulsion simulations including cavitation for an LNG carrier in extreme trim conditions

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Maasch, M. and Turan, O. and Khorasanchi, M. and Fang, Ivy (2017) Calm water resistance and self propulsion simulations including cavitation for an LNG carrier in extreme trim conditions. In: International Conference on Shipping in Changing Climates 2017, 2017-09-05 - 2017-09-06, UCL.

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Abstract

In recent years many studies and real-life applications dealing with trim optimisation have shown that operating a ship at small trim angles can improve the energy efficiency by up to 5% depending on ship speeds and loading conditions. This efficiency gain mainly results from the re-positioning of underwater hull features, such as the bulbous bow or the stern bulb. Different to the above described approach the present study deals with operating a LNG Carrier at an extreme bow-up trim angle of Ɵ = −1.9 deg. In order to predict the performance, URANS virtual towing tank simulations in calm water were performed for both, nominal resistance conditions and self-propulsion conditions including cavitation. The numerical results, including the ship resistance, the nominal propeller wake field and the simulation of propeller cavitation in self-propulsion conditions indicated a largely improved performance. Due to a significant reduction in nominal resistance by up to 27.5% the ship selfpropulsion point in extreme trim conditions was found at a lower propeller rotation rate compared to level trim conditions. This also reduced the cavitation volume and finally resulted in a delivered power reduction of up to 28.8%.

ORCID iDs

Maasch, M. ORCID logoORCID: https://orcid.org/0000-0001-8476-1971, Turan, O., Khorasanchi, M. ORCID logoORCID: https://orcid.org/0000-0002-8626-3164 and Fang, Ivy;
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