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Study on Moonpool Resonance Effect on Motion of Modern Compact Drillship

  • Received : 2013.04.10
  • Accepted : 2013.06.10
  • Published : 2013.06.30

Abstract

A drillship is a representative floating offshore installation. The boom in oil and gas field development has dramatically increased the demands for drillships. Drillships have a moonpool in the center area of the ship for the purpose of drilling. This moonpool has an effect on the seakeeping performance of a drillship in the vicinity of the resonance frequency. Because of the moonpool, drillships act in different resonance modes, called the sloshing mode and piston mode. The objective of this study was to find the moonpool effect on the motion of a drillship through the motion analysis of a currently operating modern compact drillship. The predicted resonance frequencies based on Molin's theoretical formula, Fukuda's empirical formula, and BEM-based numerical analysis are compared. The accuracy of the predictions using the theoretical and empirical formulas is compared with the numerical analysis and evaluated. In the case of the piston mode, the difference between the resonance frequency from theoretical formula and the resonance frequency from the numerical analysis is analyzed. The resonance frequency formula for more a complex moonpool geometry such as a moonpool with a cofferdam is necessarily emphasized.

Keywords

Drillship;Moonpool;Sloshing mode;Piston mode;Cofferdam

References

  1. Choi, S.Y., Lee, Y.G., Jung, K.Y., 2010. A Fundamental Study for Internal Flow in Moonpool Using Marker-Density Method by Two-Dimensional Numerical Simulation. Spring Conference of the Society of Naval Architects of Korea, Jeju.
  2. Choi, S.Y., Lee, Y.G., Jung, K.Y., Ha, Y.G., 2011. Reduction of Added Resistance by Internal Flow Control in the Moonpool of a Drillship. Journal of the Society of Naval Architects of Korea, 48, 544-551. https://doi.org/10.3744/SNAK.2011.48.6.544
  3. Fukuda, K., 1977. Behavior of Water in Vertical Well with Bottom Opening of Ship and its Effects Ship-Motion. Journal of the Society of Naval Architects of Japan, 141, 107- 122.
  4. Gaillarde, G., Cotteleer, A., 2004. Water Motion in Moonpools Empirical and Theoretical Approach, ATMA.
  5. Heo, J.K., Park, J.C., Kim, M.H., 2011. CFD Analysis of Two- Dimensional Floating Body with Moonpool under Forced Heave Motion. Journal of Ocean Engineering and Technology, 25(2), 36-46.
  6. Kooiker, K., 2011. Moonpool Mysteries. MARIN Report, 104, 18.
  7. Maisondieu, C., Ferrant, P., 2003. Evaluation of the 3D Flow dynamics in a Moonpool. Proceedings of the Thirteenth International Offshore and Polar Engineering Conference.
  8. Maritime Research Institute Netherlands (MARIN), 2009. PRECAL V6.5 Theory Manual. MARIN Report, 17926-2-CPS, 2009
  9. Molin, B., 2001. On the Piston and Sloshing Modes in Moonpools. Journal of Fluid Mechanics, 430, 27-50. https://doi.org/10.1017/S0022112000002871
  10. Newman, N., 1977. Marin Hydrodynamics. The MIT Press, Cambridge.
  11. Park, S.J., 2009. Hydrodynamic Characteristics of Moonpool shapes. MSc Thesis PNU.
  12. Taylor, R.E., Sung, L., Taylor, P.H., 2009. Gap Resonances in Focused Wave Groups. Proceedings of the 23rd International Workshop on Water Waves and Floating Bodies.
  13. Veer, R., Tholen, H.J., 2008. Added Resistance of Moonpools in Calm Water. Proceedings of the ASME 27th International Conference on Offshore Mechanics and Arctic Engineering.

Cited by

  1. Hydrodynamic Study on Water Column Oscillation of Varying Cross-Sectional Moonpool and Its Effect on Resistance of a Drill Ship vol.140, pp.3, 2017, https://doi.org/10.1115/1.4038396

Acknowledgement

Supported by : National Research Foundation of Korea (NRF)