Journal of the Korean Society of Marine Environment & Safety (해양환경안전학회지)

The Korean Society of Marine Environment and safety (해양환경안전학회)
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Empirical and Numerical Analyses of a Small Planing Ship Resistance using Longitudinal Center of Gravity Variations

경험식과 수치해석을 이용한 종방향 무게중심 변화에 따른 소형선박의 저항성능 변화에 관한 연구

  • Michael (Graduate School of Mokpo National Maritime University) ;
  • Jun-Taek Lim (Graduate School of Mokpo National Maritime University) ;
  • Nam-Kyun Im (Department of Navigation Science, Mokpo National Maritime University) ;
  • Kwang-Cheol Seo (Department of Naval Architecture & Ocean Engineering, Mokpo National Maritime University)
  • 마이클 (목포해양대학교 대학원) ;
  • 임준택 (목포해양대학교 대학원) ;
  • 임남균 (목포해양대학교 항해학부) ;
  • 서광철 (목포해양대학교 조선해양공학과)
  • Received : 2023.10.24
  • Accepted : 2023.12.29
  • Published : 2023.12.31
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Abstract

Small ships (<499 GT) constitute 46% of the existing ships, therefore, it can be concluded that they produce relatively high CO2 gas emissions. Operating in optimal trim conditions can reduce the resistance of the ship, which results in fewer greenhouse gases. An affordable way for trim optimization is to adjust the weight distribution to obtain an optimum longitudinal center of gravity (LCG). Therefore, in this study, the effect of LCG changes on the resistance of a small planing ship is studied using empirical and numerical analyses. The Savitsky method employing Maxsurf resistance and the STAR-CCM+ commercial computational fluid dynamics (CFD) software is used for the empirical and numerical analyses, respectively. Finally, the total resistance from the ship design process is compared to obtain the optimum LCG. To summarize, using numerical analysis, optimum LCG is achieved at the 46.2% length overall (LoA) at Froude Number 0.56, and 43.4% LoA at Froude Number 0.63, which provides a significant resistance reduction of 41.12 - 45.16% compared to the reference point at 29.2% LoA.

소형 선박(<499 GT)이 전체 선박의 46%를 지배하고 있어 상대적으로 많은 CO2 배출가스를 가지고 있다고 결론지을 수 있다. 최적의 Trim 조건에서 운전하면 선박의 저항을 감소시킬 수 있어 온실가스가 적게 발생할 수 있다. Trim을 최적화하는 가장 저렴한 방법 중 하나는 최적의 Longitudal Center of Gravity(LCG)를 얻기 위해 무게 분포를 조정하는 것이다. 따라서 본 연구에서는 소형 선박의 저항에 대한 LCG 변화의 영향을 경험적 및 수치적 해석을 통해 연구하고자 한다. 선체를 설계하는 Savitsky 경험식은 Maxsurf Resistance의 방법으로 사용된다. 수치해석에는 STAR-CCM+ 상용 CFD(Computational Fluid Dynamics) 소프트웨어가 사용되지만 최종적으로 선박 설계 과정 이후 최적의 LCG를 얻기 위해 전체 저항을 비교한다. 결론적으로 Froude Number 0.56에서는 수치해석에 의해 전체 길이(LoA) 46.2%에서 최적의 LCG를 달성하고 Froude Number 0.63에서는 43.4% LoA를 달성하여 29.2% LoA에서 기준점에 비해 최대 41.12% - 45.16%의 상당한 저항 감소를 얻을 수 있다.

Keywords

Acknowledgement

This research was supported by a grant (20015029) of Regional Customized Disaster-Safety R&D Program, funded by Ministry of Interior and Safety (MOIS, Korea).

References

  1. Begovic, E. and C. Bertorello(2012), Resistance assessment of warped hullform. Ocean Engineering, 56, pp. 28-42. https://doi.org/10.1016/j.oceaneng.2012.08.004
  2. Bentley(2022), MAXSURF Resistance Program & User Manual. Bentley.
  3. Elkafas, A. G., M. M. Elgohary, and A. E. Zeid(2019), Numerical study on the hydrodynamic drag force of a container ship model. Alexandria Engineering Journal, 58, pp. 849-859. https://doi.org/10.1016/j.aej.2019.07.004
  4. Equasis(2020), The 2020 world merchant fleet statistics from Equasis. Saint-Malo: Equasis.
  5. IMO(2018), Guidelines on the method of calculation of the attained energy efficiency design index (EEDI) for new ships. Marine Protection Environment Committee, MEPC.212(63).
  6. ITTC(1999), Report of the unconventional propulsor committee. the 22nd International Towing Tank Conference. Seoul: International Towing Tank Conference.
  7. ITTC(2014), ITTC - Recommended Procedures and Guidelines - Practical Guidelines for Ship CFD Applications (7.5-03-02-03). International Towing Tank Conference.
  8. Korvin-Kroukovsky, B. V., D. Savitsky, and W. F. Lehmand (1949), Wetted Area and Center of Pressure of Planing Surfaces. New Jersey: Stevens Institute of Technology, Davidson Laboratory.
  9. Seo, K. C.(2010), Application of inclined keel to large commercial ships. Newcastle: Newcastle University.
  10. Seo, K. C., N. Gopakumar, and M. Atlar(2013), Experimental investigation of dynamic trim control devices in fast speed vessel. Journal of Navigation and Port Research, 37(2), pp. 137-142. https://doi.org/10.5394/KINPR.2013.37.2.137
  11. MARPOL(2020), Regulations for the prevention of air pollution from ships. International Convention for the Prevention of Pollution from Ships.
  12. Molland, A. F., S. R. Turnock, D. A. Hudson, and I. K. Utama(2014), Reducing ship emissions: a review of potential practical improvements in the propulsive efficiency of future ships. International Journal of Maritime Engineering, 156(A2).
  13. Pacuraru, F., A. Mandru, and A. Bekhit(2022), CFD study on hydrodynamic performances of planning hull. Journal of Marine Science and Engineering, 10(1523).
  14. Pena, B., and L. Huang(2021), A review on the turbulence modelling strategy for ship hydrodynamic simulations. Ocean Engineering, 241.
  15. Pena, B., M.-P. E. Pavic, G. Thomas, and P. Fitzsimmons (2020), An approach for the accurate investigation of full-scale ship boundary layers and wakes. Ocean Engineering, 214.
  16. Reichel, M., A. Minchev, and N. L. Larsen(2014), Trim optimisation - Theory and practice. International Journal on Marine Navigation and Safety of Sea Transportation, 8(3).
  17. Roache, P.(1994), Perspective: A Method for Unifrom Reporting of Grid Refinement Studies. ASME Journal of Fluid Engineering, pp. 405-413.
  18. Savitsky, D.(1964), Hydrodynamic design of planning hulls. Marine Technology, 1, pp. 71-95.
  19. Savitsky, D. and J. Neidinger(1954), Wetted area and center of pressure of planing surfaces at very low speed coefficients. New Jersey: Stevens Institute of Technology, Davidson Laboratory.
  20. Zha, R.-S. and H.-X. Ye(2014), Numerical study of viscous wave-making resistance of ship navigation in still water. Journal of Marine Science Application, 13, pp. 158-166. https://doi.org/10.1007/s11804-014-1248-8