Study on the Estimation Methods of Roll Damping Coefficients Using Designed Excitation Device for Harmonic Roll Motion
- Byeongwon Park (Korea Research Institute of Ships & Ocean Engineering (KRISO)) | Jaesang Jung (Korea Research Institute of Ships & Ocean Engineering (KRISO)) | Dong Woo Jung (Korea Research Institute of Ships & Ocean Engineering (KRISO)) | Inbo Park (Korea Research Institute of Ships & Ocean Engineering (KRISO)) | Seok-Kyu Cho (Korea Research Institute of Ships & Ocean Engineering (KRISO)) | Hong-Gun Sung (Korea Research Institute of Ships & Ocean Engineering (KRISO))
- Document ID
- International Society of Offshore and Polar Engineers
- The 28th International Ocean and Polar Engineering Conference, 10-15 June, Sapporo, Japan
- Publication Date
- Document Type
- Conference Paper
- 2018. International Society of Offshore and Polar Engineers
- Model test, Free decay test, Harmonic excited roll motion, Roll motion excitation device, Roll damping, 30k LNG bunkering shuttle
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- 21 since 2007
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In general, the motions of floating structure are evaluated based on linear potential theory. However, because viscous effects are ignored in the linear potential theory, roll motion through potential theory may be significantly different with actual roll motion, especially at the adjacent of resonance. In this study, the estimation techniques of roll damping using free decay and harmonic excited roll motion were studied.
To design roll motion excitation device (RMED), numerical simulations are conducted for the design variables such as moving weight, moving distance and period. The test conditions are also chosen considering the results of numerical simulations. To study the roll damping of 30k LNG-BS(Bunkering Shuttle), experiments using RMED are carried out and results are analyzed by three different analysis methods for determining equivalent roll damping moment studied by Handschel et al.(2015). In addition, free decay model tests were performed, and the roll damping results were compared with the results of RMED.
Increasing demand for LNG as a fuel of ships has allowed to propose a new concept of bunkering system, known as a floating LNG bunkering terminal, FLBT which can distribute LNG to LNG fueled vessel safely and economically. The FLBT moored at a distance from a port with a turret mooring system, can load LNG from a LNG carrier, as well as storing approximately 200k of LNG capacity. The FLBT also involves LNG Bunkering shuttles (LNG-BS) which can have various storage capacities. Since LNG-BS loads LNG from the FLBT and supplies to LNG fueled vessel where they are usually berthed at a port to load and unload cargo, LNG fueled vessel can save their time in berthing and unberthing process at the typical on-land LNG bunkering terminal to load LNG fuel.
The storage capacity for LNG BS can be changed depending on the required amount of LNG fuel and FLBT system configuration. The LNG-BS loads LNG from the FLBT in side-by-side mooring configuration and then LNG-BS moves to a port and supply LNG to LNG fueled vessel. Since the LNG-BS and LNG fueled vessel also moored with side-by-side configuration, the roll motion characteristic of LNG-BS should be studied to avoid collision between ships.
|File Size||3 MB||Number of Pages||8|