A numerical investigation into the effects of Reynolds number on the flow mechanism induced by a tubercled leading edge
Tóm tắt
Leading-edge modifications based on designs inspired by the protrusions on the pectoral flippers of the humpback whale (tubercles) have been the subject of research for the past decade primarily due to their flow control potential in ameliorating stall characteristics. Previous studies have demonstrated that, in the transitional flow regime, full-span wings with tubercled leading edges outperform unmodified wings at high attack angles. The flow mechanism associated with such enhanced loading traits is, however, still being investigated. Also, the performance of full-span tubercled wings in the turbulent regime is largely unexplored. The present study aims to investigate Reynolds number effects on the flow mechanism induced by a full-span tubercled wing with the NACA-0021 cross-sectional profile in the transitional and near-turbulent regimes using computational fluid dynamics. The analysis of the flow field suggests that, with the exception of a few different flow features, the same underlying flow mechanism, involving the presence of transverse and streamwise vorticity, is at play in both cases. With regard to lift-generation characteristics, the numerical simulation results indicate that in contrast to the transitional flow regime, where the unmodified NACA-0021 undergoes a sudden loss of lift, in the turbulent regime, the baseline foil experiences gradual stall and produces more lift than the tubercled foil. This observation highlights the importance of considerations regarding the Reynolds number effects and the stall characteristics of the baseline foil, in the industrial applications of tubercled lifting bodies.
Tài liệu tham khảo
ANSYS: ANSYS-CFX Solver Theory Guide. In: ANSYS CFX 14.5.7, ed. Pennsylvania (2013)
Choudhry, A., Arjmonadi, M., Kelso, R.M.: A study of long separation bubble on thick airfoils and its consequent effects. Int. J. Heat Fluid Flow 52, 84–96 (2015)
Custodio, D.: The Effect of Humpback Whale-Like Leading Edge Protuberances on Hydrofoil Performance. Master of Science Thesis submitted to Worcester Polytechnic Institute (2007)
Dropkin, A., Custodio, D., Henoch, C.W., Johari, H.: Computation of flowfield around an airfoil with leading edge protuberances. J. Aircr. 49, 1345–1355 (2012)
Egorov, Y., Menter, F.R., Lechner, R., Cokljat, D.: The scale-adaptive simulation method for unsteady turbulent flow predictions, part 2: application to complex flows. Flow Turbul. Combust. 85, 139–165 (2010)
Favier, J., Pinelli, A., Piomelli, U.: Control of the separated flow around an airfoil using a wavy leading edge inspired by humpback whale flippers. C. R. Mec. 3401(1), 107–114 (2011)
Fish, E.F., Howle, L., Murray, M.: Hydrodynamic flow control in marine mammals. Integr. Comp. Biol. 48, 788–800 (2008)
Fish, E.F., Weber, P., Murray, M., Howle, L.: The tubercles on humpback whales’ flippers: application of bio-inspired technology. Integr. Comp. Biol. 51, 203–213 (2011)
Gregorek, M., Hoffmann, M.J., Berchak, M.J.: Steady State and Oscillatory Aerodynamic Characteristics of a NACA 0021 Airfoil: Data Report. Ohio State University, Columbus (1989)
Hansen, K.L.: Effect of Leading Edge Tubercles on Airfoil Performance. Doctor of Philosophy Thesis, Mechanical Engineering, University of Adelaide, Adelaide, SA, Australia (2012)
Hansen, K.L., Kelso, R.M., Dally, B.: An investigation of three dimensional effects on the perfomance of tubercles at low Reynolds numbers. In: Presented at the 17th Australian Fluid Mechanics Conference, Auckland, New Zealand (2010)
Hansen, K.L., Kelso, R.M., Dally, B.B.: Performance variations of leading-edge tubercles for distinct airfoil profiles. AIAA J. 49, 185–94 (2011)
Johari, H., Henoch, C., Custodio, D., Levshin, A.: Effects of leading edge protuberances on airfoil performance. AIAA J. 45(11), 2634–2642 (2007)
Langtry, R., Menter, F.: Correlation-based transition modeling for unstructured parallelized computational fluid dynamics codes. AIAA J. 47, 2894–2906 (2009)
Lohry, M., Clifton, D., Martinelli, L.: Characterization and design of tubercle leading-edge wings. In: Presented at the Computational Fluid Dynamics (ICCFD7), Big Island, Hawaii (2012)
Miklosovic, D.S., Murray, M.M., Howle, L.: Experimental evaluation of sinusoidal leading edges. J. Aircr. 44, 1404–1407 (2007)
Miklosovic, D.S., Murray, M.M., Howle, L.E., Fish, F.E.: Leading edge tubercles delay stall on humpback whale flippers. Phys. Fluids 16(5), L39–L42 (2004)
Pedro, H.T.C., Kobayashi, M.H.: Numerical study of stall delay on humpback whale flippers. In: AIAA Paper 2008–0584, pp. 7–10 (2008)
Rodriguez, D., Theofilis, V.: On the birth of stall cells on airfoils. Theor. Comput. Fluid Dyn. 25, 105–117 (2011)
Rostamzadeh, N., Hansen, K.L., Kelso, R.M., Dally, B.B.: The formation mechanism and impact of streamwise vortices on NACA 0021 airfoil’s performance with undulating leading edge modification. Phys. Fluids 26, 107101 (2014)
Rostamzadeh, N., Kelso, R.M., Dally, B.B., Hansen, K.L.: The effect of undulating leading-edge modifications on NACA 0021 airfoil characteristics. Phys. Fluids 25, 117101 (2013)
Skillen, A., Revell, A., Pinelli, A., Piomelli, U., Favier, J.: Flow over a wing with leading-edge undulations. AIAA J. 53, 1–9 (2014)
Stanway, M.J.: Hydrodynamic effects of leading-edge tubercles on control surfaces and in flapping foil propulsion. In: Master of Science in Ocean Engineering Mechanical Engineering, Massachusetts Institute of Technology (2008)
Swalwell, K.E., Sheridan, J., Melbourne, W.H.: The effect of turbulence intensity on stall of the NACA 0021 Aerofoil. In: Presented at the 14th Australasian Fluid Mechanics Conference, Adelaide University, Adelaide, Australia (2001)
van Nierop, E., Alben, S., Brenner, M.P.: How bumps on whale flippers delay stall: an aerodynamic model. Phys. Rev. Lett. 100(5), 054502 (2008)
Weber, P., Howle, L., Murray, M., Miklosovic, D.: Computational evaluation of the performance of lifting surfaces with leading-edge protuberances. J. Aircr. 48, 591–600 (2011)
Weber, P.W., Howle, L., Murray, M.: Lift, drag and cavitation onset on rudders with leading edge tubercles. Mar. Technol. 47, 27–36 (2010)
Wolfe, W.P., Ochs, S.S.: Predicting Aerodynamic Characterics of Typical Wind Turbine Airfoils using CFD. Sandia National Labratories, Iowa (1997)