IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) e-ISSN: 2278-1684,p-ISSN: 2320-334X, Volume 13, Issue 4 Ver. II (Jul. - Aug. 2016), PP 18-24 www.iosrjournals.org DOI: 10.9790/1684-1304021824 www.iosrjournals.org 18 | Page CFD Analysis ofWind Turbine Airfoil at Various Angles of Attack Ankan Dash (School of Mechanical Engineering, KIIT University, India) Abstract: The main aim of the study was to analyze the NACA0012 wind turbine airfoil at various angles of attack, keeping the Reynolds number constant. The efficiency of the aerodynamic wind turbine is greatly influenced by the aerodynamic efficiency of the airfoil. In the present study NACA0012 airfoil is considered as a suitable wind turbine blade. The geometry and analysis was done using Ansys-Fluent. Calculations were done for constant air velocity altering only the angle of attack. For the computational domain an unstructured mesh with sphere of influence and inflation was selected, taking care of the refinement of the grid near the airfoil in order to enclose the boundary layer approach. The CFD simulation results show close agreement with the results obtained from wind tunnel testing experiments, thus suggesting CFD analysis as a reliable alternative to experimental methods. Keywords: Airfoil, Angle of Attack, CFD, Drag Coefficient,Lift Coefficient I. Introduction Airfoil is defined as the cross-section of a body that is placed in an airstream in order to generate useful aerodynamic force. Compressor and turbine blades, wings of aircraft, propeller blades, windmill blades and hydrofoils are all examples of airfoils. The shape of an airfoil blade is one of the most critical partof a wind turbine, as the blade is responsible for the conversion of kinetic energy to mechanical energy.Computational Fluid Dynamics (CFD) is a branch of fluid mechanics that uses numerical methods and algorithms to solve complex problems involving fluid flow. Some of the recent interesting work in the study of airfoils has been discussed below. Patil et al. [1] investigated the effect of low Reynolds number on lift and drag for the wind turbine blade. They found out as Reynolds number increases, lift and drag forces increases.Haque et al. [2] conducted various experimental studies to understand the effects of Reynolds number and angle of attack in flow analysis. Yao et al. [3] studied the aerodynamic performance of wind turbine airfoils and compared the numerical results with experimental data. The effect of transonic flow over an airfoil has been studied and a comparative analysis hasbeen done to analyze the variation of angle of attack and Mach number [4]. The comparison of various turbulence models (Spalart-Allmaras, Realizable − and − shear stress transport) has been done and it was found out that the turbulence models used in commercial CFD codes does not give accurate results yet at high angle of attack [5]. The mechanism of laminar separation bubble and laminar- turbulent separation over the airfoil has been analyzed by Shah et al. [6] and the relationship between angle of attack and laminar bubble separation, Reynolds number and laminar bubble separation was studied. The analysis of stall angle and its effects on lift and drag coefficient was reported by Sahin et al. [7]. In the light of the review of the existing literature, the present study aims to analyze the flow field for NACA 0012 wind turbine airfoil at various angles of attack with constant Reynolds number of 10 6 . The flow was obtained by solving the steady-state governing equations of continuity and momentum conservation with Realizable − turbulence model and the results were validated by comparing with the available experimental data. Lift Coefficient (C L ): It is a dimensionless quantity that relates the lift generated by airfoil to the fluid density around the body, the fluid velocity and an associated reference area. ܥ  =  1 2  2  (1) Where, L is the lift force, ρ is the density of air, V is inlet velocity of air, A is the area of airfoil. Drag Coefficient (C D ): It is a dimensional quantity that is used to quantify the drag or resistance of an object in a fluid environment. ܥ ܦ = ܦ 1 2  2  (2)