Wing body junctions in ship hydrodynamics
Abstract
Starting with the 1st of January 2013, all ships greater than 400 gross tons have to comply with design or operational energy efficiency index, in order to reduce the greenhouse emissions. From the naval architect’s point of view, the emission reduction measures can be hydrodynamic, structural, technological and operational. The hydrodynamic measures, which are the first that can be taken into consideration in order to reduce the EEDI, are materialized through the optimization of the hull. The Naval Architect may interfere on the bulbous bow, hydrodynamic shoulders, bulb stern, transom or appendages, the drag being then modified by reducing the wave, viscous pressure or frictional resistance components. Another way to improve the hydrodynamics of a ship is the use of Energy Saving Devices (ESD). These are appendages, mounted on the ship hull, developed to improve the flow near the propeller, which operate in the non-uniform wake field of the ship. The flow mechanism around ESDs comes down to wing-body juncture flow problems and, due to their application to the ship appendage flow, they have recently received much attention in ship hydrodynamics. Despite its simple geometric configuration, the wing-body junction flow is a very complicate flow due to the so-called horseshoe vortex system determined by the adverse pressure gradient induced by the presence of the obstacle and the three-dimensional boundary layer separations around the junction. The horseshoe vortex flow affects the drag, lift and causes a persistent lack of uniformity in the wake and is also considered as one source of the noises, vibration and unsteady inflow for the propeller.
References
[2]. International Maritime Organization, “Se-cond IMO GHG Study”, Phase1, MEPC 59/INF.10, 2008/2009.
[3]. International Maritime Organization, “Se-cond IMO GHG Study”, Phase2, MEPC 59/INF.10, 2009.
[4]. International Maritime Organization, “Study of Greenhouse Gas emissions from Ships”, 2000.
[5]. International Maritime Organization, MEPC, Circ. 471, 2005.
[6]. International Maritime Organization, MEPC 62nd session, 11-15 July, 2011.
[7]. Bureau Veritas, “Energy Efficiency Design Index-EEDI, Update on New Statutory Regulations From IMO MEPC 62”, 2012.
[8]. Ungureanu C., Marcu O., IonasO., “Energy Efficiency in Ship Design”, The Annals of “Dunarea de Jos” University of Galati, Fascicle XI-Shipbuilding, pp 61-68, 2013.
[9]. AEA Energy & Environment, “Green-house gas emissions from shipping: trends, projections and abatement potential”, Report, 2008.
[10]. Det Norske Veritas, “Assessment of measures to reduce future CO2 emissions from shipping”, 2010.
[11]. MAN Diesel A/S, “Propulsion Trends in Tankers”, Copenhagen, Denmark, 2012.
[12]. Ockels, W.J., Ruiterkamp, R., Landsorp, B., “Ship propulsion by Kites combining energy production by laddermill principle and direct kite propulsion”, Kite Sailing Symposium, Washington, USA, September 28-30, 2006.
[13]. Naaijen, P., and Koster, V., “Performance of auxiliary wind propulsion for merchant ships using a kite”, The 2nd International Conference on Marine Research and Transportation, Naples, Italy, June 28-30, 2007.
[14]. Erhard, M., Strauch, H., “Control of Towing Kites Seagoing Vessels”, arXiv preprint arXiv: 1202.3641, 2012.,
[15]. Carlton J.S., “Marine propellers and propulsion”,2nd edition, ed. Butterworth - Heinemann, Elsevier, 2007.
[16]. Kessler, J., “Use of the wake equalizing duct of Schneekluth design on fast container vessels of medium size”, Schneekluth Hydrodynamik Entwicklungs-und Vertiebs- GmbH, http://www.schneekluth.com/en/.
[17]. Mewis, F., “A Novel power-Saving Device for Full-Form Vessels”, First International Symposium on Marine Propulsors, SMP’09, Trondheim, Norway, June 2009.
[18]. Baker, C.J., (1979), “The Laminar Horseshoe Vortex, Journal of Fluid Mechanics, 95.
[19]. Dickinson, S.C. “Time dependent flow visualization in the separated region of an appendage-flat plate junction”, Experiments in Fluids 6 (1988), 141.
[20]. Mehta R.D., “Effect on a wing nose shape on the flow in a wing/body junction”. Aero space. Journal, 88:456–60, 1984.
[21]. Rood E.P., “The governing influence of the nose radius on the unsteady effects of large scale flow structure in the turbulent wing and plate junction flow”, ASME Forum on Unsteady Flow, FGD, ed. PH Rothe, 15:7–9, New York, 1984c.
[22]. Fleming J., Simpson R.L., Devenport W.J. “An experimental study of a turbulent wingbody junction flow”, Experiments Fluids, 14:366–78, 1993.
[23]. Roach P.E.,Turner J.T., “Secondary loss generation by gas turbine support struts”, Int. Journal of Heat Fluid Flow, 6:79–88, 1985.
[24]. Ungureanu, C., Lungu, A., „Numerical Simulation of the Turbulent Flow around a Strut Mounted on a Plate”, Numerical Analysis and Applied Mathematics, AIP Proceedings, Melville New York, Vol. 1168, pp. 689-692, 2009.
[25]. Ungureanu, C., Lungu, A., „Numerical Investigation of the Wing-Body Junction Flows”, Annals of "Dunarea de Jos" University Galati. Fascicle XI, Shipbuilding, pp. 17-23, 2009.
[26]. Ungureanu, C., Lungu, A., „Numerical Studies on Free Surface Flow around a Hydrofoil Mounted on a Plate”, Numerical Analysis and Applied Mathematics, AIP Proceedings, Melville New York, Vol. 1281, pp. 115-118, 2010.
[27]. Ahmed A., Khan M.J., “Effect of sweep on wing-body juncture flows”, AIAA-95-0868. Presented at Am. Inst. Aeronaut. Astronaut. Aerosp. Sci. Meet., 33rd, Reno, 1995.
[28]. Bernstein L., Hamid S., “On the effect of a swept-wing/plate junction flow on the lift and drag”, Aerospace. Journal, 99:293–305, 1995.
[29]. Metcalf, B., et al., “Unsteady free surface wave-induced boundary-layer separation for a surface- piercing NACA 0024 foil: towing tank experiments”, Journal of Fluids and Structures, 22, 77–98, 2006.
[30]. Ungureanu, C., „Towing Tank Experiments for a Surface Piercing NACA 0012 Hydrofoil”, Annals of "Dunarea de Jos" University Galati. Fascicle XI, Shipbuilding, pp. 5-10, 2011.
