A Study of Model Separation Flow Behavior at High Angles of Attack Aerodynamics

Document Type : Research Paper


1 Department of Applied Mechanics, Engineering Faculty, IIT Madras, Chennai, India

2 Department of Applied Mechanics, IIT Madras, Chennai, India


This paper analyzes the aerodynamic performance and flow separation characteristics of a rectangular wing for varying Reynolds numbers. The mechanism of separation and its effect on the rectangular wing were simulated in ANSYS FLUENT using K-ω SST turbulence model. A detailed analysis was performed to discuss aspects like the lift and drag force of the wing surface, surface pressure distribution around the wing surface, flow separation characteristics for different angles of attack, velocity profiles at different sections of the wing surface along the chord length, and the effect of wing tip vortices. The simulation results showed that by increasing the angles of attack, the separation point moves towards the leading edge and the onset of stalling is very much closer to the leading edge. Also, the experimental and numerical results indicated that NACA4415 airfoil had enhanced coefficient of lift to coefficient of drag ratio at the angles of attack (AoA) ranging between 4and6,which are distinctively advantageous for the better performance of small-scale wind turbine rotors. The experimental and computational results were analyzed in the context of effective change in stalling characteristics at different Reynolds numbers.


Main Subjects

[1] Lissaman, P.B.S., Low-Reynolds-number-airfoils, Annual Review Fluid Mechanics, 15, 1983, 223-239.
[2] Carmichael, B.H., Low Reynolds Number Airfoil Survey, NASA CR-165803, 1, 1981, 19820006186.
[3] Sharma, M.S., Poddar, K., Experimental investigation of laminar separation bubble for a flow past an airfoil, Proceedings of ASME Turbo Expo 2010: Power for Land, Sea, and Air (GT2010), Glasgow, UK, 2010.
[4] Shah, H., Bhattarai, N., Lim, C.M., Mathew, S., Low Reynolds number airfoil for small horizontal axis wind turbine blades, Sustainable future energy 2012 and 10th SEE FORUM, Brunei Darussalam, 2012.
[5] Selig, M.S., Lecture notes on low Reynolds number airfoil design, VKI lecture series 8, 2003.
[6] Langtry, R.B., Menter, and F.R., Transition modeling for general CFD applications in aeronautics, 43rd AIAA Aerospace Sciences Meeting and Exhibit Reno, Nevada, 2005.
[7] Canonsburg, D.R., Fluent Theory Guide, ANSYS Academic Research, Canonsburg, 2011.
[8] Menter, P.R., Langtry, R., Voker, S., Transition modelling for general purpose CFD codes, Flow, Turbulence and Combustion, 77, 2006, 277–303.
[9] Menter, F., Zonal Two Equation K-ω Turbulence Models for Aerodynamic Flows, 23rd Fluid Dynamics, Plasma dynamics, and Lasers Conference, Orlando, FL, U.S.A., 1999.
[10] Menter, F.R., Improved Two-Equation k-ω Turbulence Models for Aerodynamic Flows, NASA Technical Memorandum, 103975, October, 1992. 
[11] Eggenspieler, G., Modelling Laminar Turbulent Transition Processes, ANSYS guide.
[12] PADT Lunch & Learn Series, ANSYS Meshing Advanced Techniques.
[13] Jones, B.M., Stalling, J. R. Aeronaut. Soc., 38, 1934, 753–770.
[14] White, N.F., Fluid Mechanics, McGraw Hill series in Mechanical Engineering, 5th edition. McGraw Hill, New York, 2002.
[15] Hu, H., Yang, Z., An Experimental Study of the Laminar Flow Separation on a Low-Reynolds-Number Airfoil, Journal of Fluids Engineering, 130(5), 2008, 051101.
[16] Hatman, A., and Wang, T., A Prediction Model for Separated Flow Transition, Journal of Turbo Machinery, 121, 1999, 594–602.
[17] Solomon, W.J., Walker, G.J., Gostelow, J.P., Transition Length Prediction for Flows with Rapidly Changing Pressure Gradients,” Journal of Turbo Machinery, 118, 1996, 744–751.
[18] Volino, R.J., Hultgren, L.S., Measurements in Separated and Transitional Boundary Layers Under Low-Pressure Turbine Airfoil Conditions, Journal of Turbo Machinery, 123, 2001, 189–197
[19] Lin, J.C.M., Pulley, L.L., Low-Reynolds-Number Separation on an Airfoil, AIAA Journal, 348, 1996, 1570–1577.
[20] Eastman, J., Sherman, A., Airfoil section characteristics as affected by variations of Reynolds number, NACA Report no. 586, 1937.
[21] McGranahan, B.D., Selig, M.S., Surface oil flow measurements on several airfoils at low Reynolds number, 21st AIAA Applied Conference, Orlando, Florida, 2003.
[22] Suzen, Y.B., Huang, P.G., Predictions of separated and transitional boundary layers under low-pressure turbine airfoil conditions using an intermittency transport equation, Journal of Turbo Machinery, 125, 2003, 455-464.
[23] Mueller, T.J., Batil, S.M., Experimental studies of separation on a two-dimensional airfoil at low Reynolds numbers, AIAA Journal, 20, 1982, 457–463.
[24] Cebeci, T., Mosinskis, G.J., Calculation of Separation Points in Incompressible Turbulent Flows, Journal of Aircraft, 9, 1972, 618-624.
[25] Stratford, S., The Prediction of Separation of the Turbulent Boundary Layer, Journal of Fluid Mechanics, 5, 1959, 1-16.
[26] Hansen, M.O.L., Aerodynamics of wind turbines, Routledge, 2013.
[27] Van den Berg, B., Role of Laminar Separation Bubbles in Airfoil Leading-Edge Stalls, AIAA Journal, 19(5), 1981, 553-556.
[28] Samal, S.K., Dash, P.K., Reduction of Wingtip Vortices by Using Active Means, International Journal of Scientific & Engineering Research, 4(4), 2013, 1280-1293.
[29] Wu, J.M. et al., Wing tip jets aerodynamics performance,” 13th Congress of the International Council of the Aeronautical Sciences/AIAA Aircraft Systems and Technology Conference, ICAS proceedings, 2, 1982, 1115-1121.
[30] Wilcox, D.C., Reassessment of the Scale-Determining Equation for Advanced Turbulence Models, AIAA Journal, 26, 1988, 1299-1310.
[31] Coakley, T.J., Turbulence Modeling Methods for the Compressible Navier-Stokes Equations, AIAA, 83, 1982.
[32] W'ilcox, D.C., Rubesin, M.W., Progress in Turbulence Modeling for Complex Flow Fields Including the Effect of Compressibility, NASA TP-1517, 1980
[33] Johnson, D.A., King, L.S., A Mathematically Simple Turbulence Closure Model for Attached and Separated Turbulent Boundary Layers, AIAA Journal, 23, 1985, 1684-1692.
[34] An Introduction to Turbulence and Its Measurement, Pergamon, Oxford, 1975
[35] Cebeci, T., Bradshaw, P., Momentum Transfer in Boundary Layers, Hemisphere, New York, 1977.
[36] Shah, H., Mathew, S., Lim, C.M., Numerical simulation of flow over an airfoil for small wind turbines using the γ-ReӨ model, International Journal of Energy and Environmental Engineering, 6(4), 2015, 419–429.
[37] J.D Anderson, Fundamentals of Aerodynamics, McGraw-Hill Education, 5th edition, February 12, 2010.
[38] Moffat, R.J., Using uncertainty analysis in the planning of an experiment, Journal of Fluids Engineering, 107(2), 1985, 173-178.
[39] Kline, S.J., McClintock, F.A., Describing Uncertainties in Single-Sample Experiments, Mechanical Engineering, 75(1), 1953, 3-8.