DOI QR코드

DOI QR Code

Effect of flap angle on transom stern flow of a High speed displacement Surface combatant

  • Hemanth Kumar, Y. (Department of Ocean Engineering, Indian Institute of Technology) ;
  • Vijayakumar, R. (Department of Ocean Engineering, Indian Institute of Technology)
  • 투고 : 2019.03.18
  • 심사 : 2019.11.15
  • 발행 : 2020.03.25

초록

Hydrodynamic Drag of Surface combatants pose significant challenges with regard to fuel efficiency and exhaust emissions. Stern flaps have been used widely as an energy saving device, particularly by the US Navy (Hemanth et al. 2018a, Hemanth Kumar and Vijayakumar 2018b). In the present investigation the effect of flap turning angle on drag reduction is numerically and experimentally studied for a high-speed displacement surface combatant fitted with a stern flap in the Froude number range of 0.17-0.48. Parametric investigations are undertaken for constant chord length & span and varying turning angles of 5° 10° & 15°. Experimental resistance values in towing tank tests were validated with CFD. Investigations revealed that pressure increased as the flow velocity decreased with an increase in flap turning angle which was due to the centrifugal action of the flow caused by the induced concave curvature under the flap. There was no significant change in stern wave height but there was a gradual increase in the stern wave steepness with flap angle. Effective length of the vessel increased by lengthening of transom hollow. In low Froude number regime, flow was not influenced by flap curvature effects and pressure recovery was marginal. In the intermediate and high Froude number regimes pressure recovery increased with the flap turning angle and flow velocity.

키워드

과제정보

Authors thankfully acknowledge the technical support provided by the Department of Ocean Engineering, Indian Institute of Technology Madras in providing High-speed computing facilities, Towing tank and Instrumentation for undertaking simulations and conducting the experiments. We are also, indebted to Prof. Anantha Subramanian, Professor, Department of Ocean Engineering, for all the support rendered towards successfully completing research investigations.

참고문헌

  1. Cave, C. (1993), "Effect of stern flaps on powering performance of the FFG-7 class", 30(1), 39-50. https://doi.org/10.5957/mt1.1993.30.1.39
  2. Doctors, L. (2006), "Influence of the transom-hollow length on wave resistance", Proceedings of the 1st International Workshop on Water Waves and Floating Bodies (21 IWWWFB), Loughborough, England.
  3. Doctors, L., Macfarlane, G.J. and Young, R. (2007), "A study of transom-stern ventilation", Int. Shipbuild. Progress, 54(2-3), 145.
  4. Eslamdoost, A., Larsson, L. and Bensow, R. (2015), "On transom clearance", Ocean Eng., 99, 55-62. doi: 10.1016/j.oceaneng.2015.02.008.
  5. Hemanth Kumar, Y. and Vijayakumar, R. (2018a), "Review of hydrodynamic performance of stern flap", Proceedings of the International Conference on Computational and Experimental Marine Hydrodynamics MARHY 2018, 26-27 November 2018, IIT Madras, Chennai, India. Chennai.
  6. Hemanth Kumar, Y. and Vijayakumar, R. (2018b) "Stern flaps : A cost-effective technological option for the Indian shipping industry", Maritime Affairs: J. National Maritime Foundation of India, 14(2), 26-37. Available at: https://doi.org/10.1080/09733159.2018.1562454.
  7. John, S., et al. (2011), "Hydrodynamic performance enhancement using stern wedges", Stern Flaps and Interceptors", Proceedings of the International Conference in Ship & Offshore Technology. Kharagpur, India.
  8. Karafiath, G., et al. (2001), "Hydrodynamic efficiency improvements Ft WPB ISLAND class patrol boats to the USCG 110", 109, 197-220.
  9. Karafiath, G., Cusanelli, D.S. and Lin, C.W. (1999), "Stern wedges and stern flaps for improved powering-US Navy experience", T. Soc. Naval Archit. Marine Engineers, 107, 67-99.
  10. Lars Larsson, W.S. (2010), The Principles of Naval Architecture Series:Resistance.
  11. Maki, A., et al. (2016), "Fundamental research on resistance reduction of surface combatants due to stern flaps", J. Marine Sci. Technol. (Japan), 21(2), 344-358. doi: 10.1007/s00773-015-0356-8.
  12. Orych, M. and Larsson, L. (2015), "Hydrodynamic aspects of transom stern optimization", 10-12.
  13. Thornhill, E., Cusanelli, D. and Cumming, D. (2008), "Stern flap resistance reduction for displacement hulls", Proceedings of the 27th Symposium on Naval Hydrodynamics, 3(October).
  14. Yamano, T., Kusunoki, Y., Kuratani, F., Ogawa, T. and Teturo Ikebuchi, I. F. (2003), "Effect of transom stern bottom profile form on stern wave resistance− A consideration on the effect of real stern end immersion", J. Kansai Soc.N.A.,Japan, (240), 9.