Abstract
An experimental study of flow separation control on a low-Re c airfoil was presently investigated using a newly developed leading-edge protuberance method, motivated by the improvement in the hydrodynamics of the giant humpback whale through its pectoral flippers. Deploying this method, the control effectiveness of the airfoil aerodynamics was fully evaluated using a three-component force balance, leading to an effectively impaired stall phenomenon and great improvement in the performances within the wide post-stall angle range (22°–80°). To understand the flow physics behind, the vorticity field, velocity field and boundary layer flow field over the airfoil suction side were examined using a particle image velocimetry and an oil-flow surface visualization system. It was found that the leading-edge protuberance method, more like low-profile vortex generator, effectively modified the flow pattern of the airfoil boundary layer through the chordwise and spanwise evolutions of the interacting streamwise vortices generated by protuberances, where the separation of the turbulent boundary layer dominated within the stall region and the rather strong attachment of the laminar boundary layer still existed within the post-stall region. The characteristics to manipulate the flow separation mode of the original airfoil indicated the possibility to further optimize the control performance by reasonably designing the layout of the protuberances.
Similar content being viewed by others
References
Brain C, Donald C (1983) An experimental study of entrainment and transport in the turbulent near wake of a circular cylinder. J Fluid Mech 136:321–374
Coleman H, Steele W (1989) Experimentation and uncertainty analysis for engineers. Wiley-Interscience, New York
Custodio D (2007) The effect of humpback whale-like leading edge protuberances on hydrofoil performance. Master Dissertation, Worcester Polytechnic Institute
Devinant P, Laverne T, Hureau J (2002) Experimental study of wind-turbine airfoil aerodynamics in high turbulence. J Wind Eng Ind Aerod 90:689–707
Dovgal AV, Kozlov VV, Michalke A (1994) Laminar boundary layer separation: instability and associated phenomena. Prog Aerospace Sci 30:61–94
Dropkin A, Custodio D, Henoch CW, Johari H (2012) Computation of flowfield around an airfoil with leading-edge protuberances. J Aircraft 49(5):1345–1355
Favier J, Pinelli A, Piomelli U (2012) Control of the separated flow around an airfoil using a wavy leading edge inspired by humpback whale flippers. C R Mecanique 340:107–114
Fish FE, Battle JM (1995) Hydrodynamic design of the humpback whale flipper. J Morphol 225:51–60
Fish FE, Lauder GV (2006) Passive and active flow control by swimming fishes and mammals. Annu Rev Fluid Mech 38:193–224
Fish FE, Weber PW, Murray MM, Laurens EH (2011) The tubercles on humpback whales’ flippers: application of bio-inspired technology. Integr Comp Biol 51(1):203–213
Fouras A, Soria J (1998) Accuracy of out-of-plane vorticity measurements derived from in-plane velocity field data. Exp Fluids 25:409–430
Gaulf DE (1957) A correlation of low-speed, airfoil-section stalling characteristics with Reynolds number and airfoil geometry. NACA TN3963
Hackett JE, Cooper KR (2001) Extensions to the Maskell’s theory for blockage effects on bluff bodies in a closed wind tunnel. Aeronaut J 105:409–418
Hansen KL, Kelso RM, Dally BB (2011) Performance variations of leading-edge tubercles for distinct airfoil profiles. AIAA J 49(1):185–194
Huang RF, Mao SW (2002) Separation control on a cantilever wing with a self-excited vibrating rod. J Aircraft 39(4):609–615
Johari H, Henoch C, Custodio D, Levshin A (2007) Effects of leading-edge protuberances on airfoil performance. AIAA J 45(11):2634–2642
Levshin A, Custodio D, Henoch C, Johari H (2006) Effects of leading edge protuberances on airfoil performance. In: Proceeding of 36th AIAA fluid dynamics conference and exhibit, San Francisco, California, AIAA 2006–2868
Lin JC (2002) Review of research on low-profile vortex generators to control boundary-layer separation. Prog Aerosp Sci 38:389–420
Lin JC, Pauley LL (1996) Low-Reynolds-number separation on an airfoil. AIAA J 34:1570–1577
Lin YF, Lam K, Zhou L, Liu Y (2013) Numerical study of flows past airfoils with wavy surfaces. J Fluid Struct 36:136–148
Lissaman PBS (1983) Low-reynolds-number airfoils. Annu Rev Fluid Mech 15:223–239
Maskell EG (1963) Theory of blockage effects on bluff bodies and stalled wings in a closed wind tunnel. ARC R&M 3400
McCullough GB, Gault DE (1951) Examples of three representative types of airfoil-section stall at low speed. NACA TN2502
Miklosovic DS, Murray MM, Howle LE, Fish FE (2004) Leading-deg tubercles delay stall on humpback whale (Megaptera novaeangliae) flippers. Phys Fluids 16(5):39–42
Miklosovic DS, Murray MM, Howle LE (2007) Experimental evaluation of sinusoidal leading edges. J Aircraft 44(4):1404–1407
Mueller TJ, DeLaurier JD (2003) Aerodynamics of small vehicles. Annu Rev Fluid Mech 35:89–111
Pedro HTC, Kobayashi MH (2008) Numerical study of stall delay on humpback whale flippers. In: Proceeding of 46th AIAA Aerospace Sciences Meeting and Exhibit, Reno, Nevada
Raghunathan S, Harrison JR, Hawkins BD (1988) Thick airfoil at low Reynolds number and high incidence. J Aircraft 25:669–671
Stanway MJ (2008) Hydrodynamic effect of leading-edge tubercles on control surfaces and in flapping foil propulsion. Master Dissertation, Department of Mechanical Engineering, Massachusetts Institute of Technology
Timmins BH, Wilson BW, Smith BL, Vlachos PP (2012) A method for automatic estimation of instantaneous local uncertainty in particle image velocimetry measurements. Exp Fluids 53:1133–1147
Torenbeek E (1982) Synthesis of subsonic airplane design. Delft University Press, The Netherlands
van Nierop EA, Alben S, Brenner MP (2008) How bumps on whale flippers delay stall: an aerodynamic model. Phys Rev Lett 100:054502
Watts P, Fish FE (2001) The influence of passive, leading edge tubercles on wing performance. In: Proceeding of 12th Unmanned Untethered Submersible Technology (UUST01), Autonomous Undersea Systems Inst., Durham, NH
Weber PW, Howle LE, Murray MM, Miklosovic DS (2011) Computational evaluation of the performance of lifting surfaces with leading-edge protuberances. J Aircraft 48(2):591–600
West GS, Apelt CJ (1982) The effect of tunnel blockage and aspect ratio on the mean flow past a circular cylinder with Reynolds number between 104 and 2.5 × 105. J Fluid Mech 114:361–377
Wilson BM, Smith BL (2013) Taylor-series and Monte-Carlo-method uncertainty estimation of the width of a probability distribution based on varying bias and random error. Meas Sci Technol 24:035301
Wright AK, Wood DH (2004) The starting and low wind speed behavior of a small horizontal axis wind turbine. J Wind Eng Ind Aerodyn 92:1265–1279
Zhang MM, Wang GF, Xu JZ (2013) Aerodynamic control of low-Reynolds-number airfoil with leading-edge protuberances. AIAA J 51(8):1960–1971
Acknowledgments
This work was supported by the National Natural Science Foundation of China (Grant No. 51222606) and the “Hundred Talent Program” of the Chinese Academy of Sciences.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Zhang, M.M., Wang, G.F. & Xu, J.Z. Experimental study of flow separation control on a low-Re airfoil using leading-edge protuberance method. Exp Fluids 55, 1710 (2014). https://doi.org/10.1007/s00348-014-1710-z
Received:
Revised:
Accepted:
Published:
DOI: https://doi.org/10.1007/s00348-014-1710-z