1
Islamic Azad University, Science and Research Branch of Tehran
2
Technical Engineering Faculty, Aerospace Engineering Department Islamic Azad University, Science And Research Branch
Abstract
This study is conducted on the effects of leading-edge slat and longitudinal slots in delaying the flow separation. The case study is a conventional wind turbine airfoil and four different types of slots have been investigated. The aerodynamic simulation is performed on the basis of a steady state air flow over the NREL S809 airfoil and the solution is obtained numerically using the structured grids. The results show that at Reynolds number of 1e+6 and an angle of attack equal to 16.22o, with the addition of leading-edge slat, the separation is delayed from x / c = 0.47 to x / c = 0.67 and the lift coefficient is increased by 64% (from 1.17 to 1.92). So, by adding several types of longitudinal slots, it is observed that a sinusoidal slot with 45o of phase lead, has the best performance.Through studying the values of the aperture, depth and location of the sinusoidal slot, the best values of these parameters were obtained as follows: 3% of the chord for the aperture value, 0.5% of the chord for the depth value and 0.85 for the x/c ratio. By completely removing the flow separation, at the mentioned Reynolds number with the same angle of attack, the lift coefficient has 117% increase, reaching the value of 2.54.
Willert, C.E., Cuvier, C., Foucaut, J.M., Klinner, J., Stanislas, M., Laval, J.P., Srinath, S., Soria, J., Amili, O., Atkinson, C. and Kähler, C.J. “Experimental Evidence of Near-wall Reverse Flow Events in a Zero Pressure Gradient Turbulent Boundary Layer”, Exp. Therm. Fluid Sci., Vol. 91, pp. 320–328, 2018.
Berg, Dale E. and Johnson, Scott J. (University of California, Davis, CA) “Active Load Control Techniques for Wind Turbines”, Report, July 1,2008; UnitedStates. (https://digital.library.unt.edu/ark:/67531/metadc895537/: accessed August 25, 2021), University of North Texas Libraries,
Martinstetter, M. and Niehuis“Passive Boundary Layer Control on a Highly Loaded Low Pressure Turbine Cascade”, Turbo Expo: Power for Land, Sea, and Air,Vol. 44021,No. GT2010-22739,pp. 1315-1326, 2010.
Yen,J. and Ahmed,N. A. “Enhancing Vertical Axis Wind Turbine By Dynamic Stall Control Using Synthetic Jets”, J. Wind Eng. Ind. Aerodyn., Vol. 114, no. 0167-6105, pp. 12–17, 2013.
Feng,J.,Lin,Y.,Zhu,G. and Luo,X. “Effect of Synthetic Jet Parameters on Flow Control of an Airfoil at High Reynolds Number”,Sadhana - Acad. Proc. Eng. Sci., Vol. 44, no. 8, pp. 9-12, 2019.
Wang, H., Jiang, X., Chao, Y., Li, Q., Li, M., Zheng, W. and Chen, T.“Effects of Leading-Edge Slat onFlow Separation and Aerodynamic Performance of Wind Turbine”, Energy, Vol. 182, pp. 988–998, 2019, doi: 10.1016/j.energy.2019.06.096.
Chen,T.,Jiang,X.,Wang,H.,Li,Q.,Li, M. and Wu,Z. “Investigation of Leading-Edge Slat on Aerodynamic Performance of Wind Turbine Blade”, Proc. Inst. Mech. Eng. Part C., J. Mech. Eng. Sci., Vol. 0, no. 0, pp. 1–15, 2020.
James, S.,Suryan, A.,Sebastian, J.,and Mohan, A. H. K.-C. “Comparative Study of Boundary Layer Control Around an Ordinary Airfoil and a High Lift Airfoil with Secondary Blowing”,Computers & Fluids, Vol. 164, No. 0045-7930, pp. 50-63, 2018.
Wang,H.,Zhang, B.,Qiu, Q. and Xu, X. “Flow Control on the NREL S809 Wind Turbine Airfoil Using Vortex Generators”,Energy, Vol. 118, no. 0360-5442, pp. 1210–1221, 2017.
Zhong, J.,Li, J.,Guo, P. and Wang, Y. “Dynamic Stall Control on a Vertical Axis Wind Turbine Airfoil Using Leading-Edge Rod”, Energy, Vol. 174, no. 0360-5442, pp. 246–260, 2019.
Hao,L. S. and Gao, Y. W. “Effect of Gurney Flap Geometry on a S809 Airfoil”, Int. J. Aerosp. Eng., Vol. 2019, pp. 1687-5966, DOI:10.1155/2019/9875968
Belamadi, R.,Djemili, A.,Ilinca, A. and Mdouki, R. “Aerodynamic performance analysis of slotted airfoils for application to wind turbine blades”, J. Wind Eng. Ind. Aerodyn., Vol. 2019, no. 2019, pp. 1687-5966,
Moshfeghi, M.,Shams, Sh.,Ramezani M. and Hur, N.K.“Effect of Split on Flow Separation Reduction of Wind Turbine Airfoil Using DES Turbulence Model”, Modares Mechanical Engineering, Vol. 20, no. 2, pp. 381–390, 2020, (In Persian).
Xie, Y.,Chen, J.,Qu, H.,Xie, G.,Zhang, D. and Moshfeghi, M. “Numerical and Experimental Investigation on the Flow Separation Control of S809 Airfoil with Slot”, Math. Probl. Eng., Vol. 2013, No. 301748, 2013..
Beyhaghi,S. and Amano, R. S. “Improvement of Aerodynamic Performance of Cambered Airfoils Using Leading-Edge Slots”, J. Energy Resour. Technol., Vol. 139, no. 5, pp. 12-16, 2017.
Beyhaghi,S. and Amano,R. S. “A Parametric Study on Leading-Edge Slots Used on Wind Turbine Airfoils at Various Angles of Attack”, J. Wind Eng. Ind. Aerodyn., Vol. 175, no. 0167-6105, pp. 43–52, 2018.
Akbarzadeh,M. and Birouk, M. “Near-Field Characteristics of a Rectangular Jet and Its Effect on the Liftoff of Turbulent Methane Flame”, J. Eng. Gas Turbines Power, Vol. 137, no. 8, pp. 1-8, 2015.
Sanieinejad,M. "Fundamentals of Turbulent Flows and Their Modeling”, Publisher: Danesh Negar, Isbn. 978-964-2927-35-7 pp. 728-740, Iran, 2017.
Heidarinejad, Gh. "An Introduction to Turbulence”,Publisher: Tarbiat Modares University, Isbn. 60075897062010, pp. 145-196, Iran, 2018.##
Gladwell, I.“Boundary Value Problem”,Scholarpedia, Vol. 3, no. 1,pp. 2853,2008.
Somers, D. M. “Design and Experimental Results for the S809 Airfoil”,National Renewable Energy Lab., Golden, CO (United States), p. 104, 1997.
fallahzadeh,M. “Numerical Study of Camber Effect on the Aerodynamic Performance of Corrugated Airfoils”, M.Sc. Thesis, Shiraz University of Technology Department of Mechanical and Aerospace Engineering,2014.
Moshfeghi, M.,Shams, S.,Ramezani, M. and Hur,N. “Effect of Split on Flow Separation Reduction of Wind Turbine Airfoil Using DES Turbulence Model”, Modares Mech. Eng., Vol. 20, no. 2, pp. 381-390, 2020.
Saeedi, M., & aghaei tough, R. (2021). Delay in flow separation on wind turbine blade by combining slat effect and longitudinal slot. Fluid Mechanics & Aerodynamics, 9(2), 39-52.
MLA
Mohammad Saeedi; Reza aghaei tough. "Delay in flow separation on wind turbine blade by combining slat effect and longitudinal slot", Fluid Mechanics & Aerodynamics, 9, 2, 2021, 39-52.
HARVARD
Saeedi, M., aghaei tough, R. (2021). 'Delay in flow separation on wind turbine blade by combining slat effect and longitudinal slot', Fluid Mechanics & Aerodynamics, 9(2), pp. 39-52.
VANCOUVER
Saeedi, M., aghaei tough, R. Delay in flow separation on wind turbine blade by combining slat effect and longitudinal slot. Fluid Mechanics & Aerodynamics, 2021; 9(2): 39-52.
)
