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

M. Maasch, O. Turan, M. Khorasanchi, Ivy Fang

Research output: Contribution to conferencePaperpeer-review

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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%.
Original languageEnglish
Number of pages10
Publication statusPublished - 5 Sep 2017
EventInternational Conference on Shipping in Changing Climates 2017 - UCL, London, United Kingdom
Duration: 5 Sep 20176 Sep 2017
http://www.lowcarbonshipping.co.uk/index.php?option=com_content&view=article&id=70&Itemid=188

Conference

ConferenceInternational Conference on Shipping in Changing Climates 2017
Abbreviated titleSCC 2017
Country/TerritoryUnited Kingdom
CityLondon
Period5/09/176/09/17
Internet address

Keywords

  • extreme trim operation
  • unsteady RANSE
  • calm water resistance performance
  • automatic wake analysis
  • self-propulsion performance
  • cavitation simulation

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