Numerical Investigation on the Effect of Leading-Edge Tubercles on the Laminar Separation Bubble

Document Type : Regular Article


1 Department of Mechanical Engineering, National Institute of Technology Karnataka, Mangaluru, Karnataka, India-575025, India

2 Department of Mechanical Engineering, AJ Institute of Engineering and Technology, Mangaluru, Karnataka, India-575006, India



The effect of leading-edge tubercles on the aerodynamic performance of E216 airfoil is studied by steady 3D numerical simulations using Transition γ−Reθ turbulance model. The investigation is carried out for the various angles of attack in the pre-stall region at Reynolds number of 100,000. Various tubercle configurations with different combinations of amplitude ranging from 2 mm to 8 mm and wavelength varying from 15.5mm to 62 mm are studied. The effect of tubercle parameters on the laminar separation bubble (LSB) is extensively studied. Improvement in the coefficient of lift (Cl) is observed for most of the tubercled models and is significant at high angles of attack. But the simultaneous increase in the drag coefficient resulted in a marginal improvement in the coefficient of lift to drag ratio (Cl/Cd) for most of the cases except for A2W62, which produced a peak value of 46.91 at AOA 6which is higher than that for the baseline by 7.37%. Compared to the baseline, the magnitude of suction peak is higher along the trough and lower along the peak. The low amplitude and low wavelength tubercle model exhibited smooth surface pressure coefficient (Cp) distribution without any sign of strong LSB formation. The LSB moves upstream with the increase in amplitude and wavelength. The LSB along the trough is formed ahead of that at peak inducing three-dimensional wavy shaped LSB unlike the straight LSB as in baseline. Two pairs of counter rotating vortices are formed on the airfoil surface between the adjacent peaks at two different chord-wise locations which strongly alter the flow pattern over it.


Arai, H., Y. Doi, T. Nakashima and H. Mutsuda (2010). A study on stall delay by various wavy leading edges. Journal of aero aqua bio-mechanisms 1(1), 18–23.##
Bolzon, M. D., R. M. Kelso and M. Arjomandi (2015). Tubercles and their applications. Journal of Aerospace Engineering 29(1), 04015013.##
Bolzon, M. D., R. M. Kelso and M. Arjomandi (2016). Formation of vortices on a tubercled wing, and their effects on drag. Aerospace Science and Technology 56, 46–55.##
Bolzon, M. D., R. M. Kelso and M. Arjomandi (2017a). Force measurements and wake surveys of a swept tubercled wing. Journal of Aerospace Engineering 30(3), 04016085.##
Bolzon, M. D., R. M. Kelso and M. Arjomandi (2017b). Performance effects of a single tubercle terminating at a swept wing’s tip. Experimental Thermal and Fluid Science 85, 52–68.##
Bushnell, D. M. and K. Moore (1991). Drag reduction in nature. Annual Review of Fluid Mechanics 23(1), 65–79.##
Cai, C., Z. Zuo, S. Liu and Y. Wu (2015). Numerical investigations of hydrodynamic performance of hydrofoils with leading-edge protuberances. Advances in Mechanical Engineering 7(7), 1687814015592088.##
Cai, C., Z. Zuo, T. Maeda, Y. Kamada, Q. Li, K. Shimamoto and S. Liu (2017). Periodic and aperiodic flow patterns around an airfoil with leading-edge protuberances. Physics of fluids 29(11), 115110.##
Carreira Pedro, H. and M. Kobayashi (2008). Numerical study of stall delay on humpback whale flippers. In 46th AIAA aerospace sciences meeting and exhibit, pp. 584.##
Chishty, M. A., K. Parvez, S. Ahmed, H. R. Hamdani and A. Mushtaq (2011). Transition prediction in low pressure turbine (lpt) using gamma theta model and passive control of separation. In ASME 2011 International Mechanical Engineering Congress and Exposition, pp. 193–200. American Society of Mechanical Engineers Digital Collection.##
Crivellini, A., V. D’Alessandro, D. Di Benedetto, S. Montelpare and R. Ricci (2014). Study of laminar separation bubble on low reynolds number operating airfoils: Rans modelling by means of an high-accuracy solver and experimental verification. In Journal of Physics: Conference Series, Volume 501, pp. 012024. IOP Publishing.##
Custodio, D. S. (2007). The effect of humpback whale-like protuberances on hydrofoil performance.##
de Paula, A. A., J. Meneghini, V. G. Kleine and R. D. Girardi (2017). The wavy leading edge performance for a very thick airfoil. In 55th AIAA Aerospace Sciences Meeting, pp. 0492.##
Fagbenro, K., M. Mohamed and D. Wood (2014). Computational modeling of the aerodynamics of windmill blades at high solidity. Energy for Sustainable Development 22, 13– 20.##
Favier, J., A. Pinelli and U. Piomelli (2012). Control of the separated flow around an airfoil using a wavy leading edge inspired by humpback whale flippers. Comptes Rendus Mecanique 340(1-2), 107–114.##
Filho, G. B., A. L. Da Costa, A. A. de Paula and G. R. De Lima (2018). A numerical investigation of the wavy leading edge phenomena at transonic regime. In 2018 AIAA Aerospace Sciences Meeting, pp. 0317.##
Fish, F. E. and J. M. Battle (1995). Hydrodynamic design of the humpback whale flipper. Journal of Morphology 225(1), 51–60.##
FLUENT (2014). 15.0. Theory Guide.##
Genc, M. S., I. Karasu, H. H. Acikel, M. T. Akpolat and M. Genc (2012). Low reynolds number flows and transition. Low Reynolds Number Aerodynamics and Transition, Genc, MS Ed.; InTech: Rijeka, Croatia, 1–28.##
Godard, G. and M. Stanislas (2006). Control of a decelerating boundary layer. part 1: Optimization of passive vortex generators. Aerospace Science and Technology 10(3), 181–191.##
Hansen, K. L. (2012). Effect of leading edge tubercles on airfoil performance. Ph. D. thesis.##
Hansen, K. L., R. M. Kelso and B. B. Dally (2011). Performance variations of leadingedge tubercles for distinct airfoil profiles. AIAA journal 49(1), 185–194.##
Hansen, K. L., N. Rostamzadeh, R. M. Kelso and B. B. Dally (2016). Evolution of the streamwise vortices generated between leading edge tubercles. Journal of Fluid Mechanics 788, 730–766.##
Hu, H. and Z. Yang (2008). An experimental study of the laminar flow separation on a low-reynolds-number airfoil. Journal of Fluids Engineering 130(5), 051101.##
Johari, H., C. W. Henoch, D. Custodio and A. Levshin (2007). Effects of leading-edge protuberances on airfoil performance. AIAA Journal 45(11), 2634–2642.##
Lu, Y., Z. Li, X. Chang, Z. Chuang and J. Xing (2021). An aerodynamic optimization design study on the bio-inspired airfoil with leading-edge tubercles. Engineering Applications of Computational Fluid Mechanics 15(1), 293–313.##
Lyon, C., M. Selig, A. Broeren, C. Lyon, M. Selig and A. Broeren (1997). Boundary layer trips on airfoils at low Reynolds numbers. In 35th Aerospace Sciences Meeting and Exhibit, pp. 511.##
Menter, F., R. Langtry and S. V lker (2006a). Transition modelling for general purpose cfd codes. Flow, turbulence and combustion 77(1-4), 277–303.##
Menter, F. R., R. B. Langtry, S. Likki, Y. Suzen, P. Huang and S. V lker (2006b). A correlation-based transition model using local variables—part i: model formulation. Journal of turbomachinery 128(3), 413–422.##
Miklosovic, D., M. Murray, L. Howle and F. Fish (2004). Leading-edge tubercles delay stall on humpback whale (megaptera novaeangliae) flippers. Physics of Fluids 16(5), L39–L42.##
Miklosovic, D. S., M. M. Murray, and L. E. Howle (2007). Experimental evaluation of sinusoidal leading edges. Journal of Aircraft 44(4), 1404–1408.##
Musial, W. and D. Cromack (1988). Influence of reynolds number on performance modeling of horizontal axis wind rotors. Journal of Solar Energy Engineering 110(2), 139–144.##
Ozen, C. and D. Rockwell (2010). Control of vortical structures on a flapping wing via a sinusoidal leading-edge. Physics of fluids 22(2), 021701.##
Rahimi, H., W. Medjroubi, B. Stoevesandt and J. Peinke (2014). 2d numerical investigation of the laminar and turbulent flow over different airfoils using openfoam. In Journal of Physics: Conference Series, Volume 555, pp. 012070. IOP Publishing.##
Rostamzadeh, N., K. Hansen, R. Kelso and B. Dally (2014). The formation mechanism and impact of streamwise vortices on naca 0021 airfoil’s performance with undulating leading edge modification. Physics of Fluids 26(10), 107101.##
Rostamzadeh, N., R. Kelso, B. Dall and K. Hansen (2013). The effect of undulating leading-edge modifications on naca 0021 airfoil characteristics. Physics of fluids 25(11), 117101.##
Serson, D. and J. Meneghini (2015). Numerical study of wings with wavy leading and trailing edges. Procedia Iutam 14, 563–569.##
Serson, D., J. Meneghini and S. Sherwin (2017). Direct numerical simulations of the flow around wings with spanwise waviness at a very low Reynolds number. Computers & Fluids 146, 117–124.##
Shah, H., S. Mathew and C. M. Lim (2015). Numerical simulation of flow over an airfoil for small wind turbines using the γ-Reθ model. International Journal of Energy and Environmental Engineering 6(4), 419–429.##
Sheikholeslami, M. and D. Domiri Ganji (2017). Turbulent heat transfer enhancement in an air-to-water heat exchanger. Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 231(6), 1235–1248.##
Skillen, A., A. Revell, A. Pinelli, U. Piomelli and J. Favier (2015). Flow over a wing with leading-edge undulations. Aiaa Journal 53(2), 464–472.##
Sreejith, B. and A. Sathyabhama (2018). Numerical study on effect of boundary layer trips on aerodynamic performance of e216 airfoil. Engineering science and technology, an international Journal 21(1), 77–88.##
Sreejith, B. and A. Sathyabhama (2020). Experimental and numerical study of laminar separation bubble formation on low Reynolds number airfoil with leading-edge tubercles. Journal of the Brazilian Society of Mechanical Sciences and Engineering 42(4), 1–15.##
Stanway, M. J. (2008). Hydrodynamic effects of leading-edge tubercles on control surfaces and in flapping foil propulsion. Ph. D. thesis, Massachusetts Institute of Technology.##
Stark, C., W. Shi and M. Atlar (2021). A numerical investigation into the influence of bio-inspired leading-edge tubercles on the hydrodynamic performance of a benchmark ducted propeller. Ocean Engineering 237, 109593.##
Stein, B. and M. Murray (2005). Stall mechanism analysis of humpback whale flipper models. Proceedings of Unmanned Untethered Submersible Technology (UUST), UUST05 5.##
Sudhakar, S., N. Karthikeyan and P. Suriyanarayanan (2019). Experimental studies on the effect of leading-edge tubercles on laminar separation bubble. AIAA Journal 57(12), 5197–5207.##
Van Nierop, E. A., S. Alben, and M. P. Brenner (2008). How bumps on whale flippers delay stall: an aerodynamic model. Physical Review Letters 100(5), 054502.##
Watts, P. and F. E. Fish (2001). The influence of passive, leading edge tubercles on wing performance. In Proc. Twelfth Intl. Symp. Unmanned Untethered Submers. Technol. Auton. Undersea Syst. Inst. Durham New Hampshire.##
Weber, P. W., L. E. Howle, M. M. Murray and D. S. Miklosovic (2011). Computational evaluation of the performance of lifting surfaces with leading-edge protuberances. Journal of Aircraft 48(2), 591–600.##
Wei, Z., T. New and Y. Cui (2015). An experimental study on flow separation control of hydrofoils with leading-edge tubercles at low reynolds number. Ocean Engineering 108, 336–349.##
Wei, Z., T. H. New and Y. Cui (2018). Aerodynamic performance and surface flow structures of leading-edge tubercled tapered swept-back wings. AIAA Journal 56(1), 423–431.##
Wei, Z., J. Toh, I. Ibrahim and Y. Zhang (2019). Aerodynamic characteristics and surface flow structures of moderate aspectratio leading-edge tubercled wings. European Journal of Mechanics-B/Fluids 75, 143–152.##
Zhang, M. and A. Frendi (2016). Effect of airfoil leading edge waviness on flow structures and noise. International Journal of Numerical Methods for Heat & Fluid Flow##
Volume 15, Issue 3 - Serial Number 64
May and June 2022
Pages 767-780
  • Received: 22 April 2021
  • Revised: 08 November 2021
  • Accepted: 12 November 2021
  • Available online: 14 March 2022