1. Numerical Analysis of Vertical Axis WindTurbineMohammad Rashedul Hasan, Md. Rasedul Islam,G.M Hasan Shahariar and Dr. Mohammad MashudDepartment of Mechanical EngineeringKhulna University of Engineering & Technology, Khulna, BangladeshIFOST-2014, Bangladesh

2. OUTLINE Introduction Objectives Boundary condition Mesh generation Assumptions Mathematical formula Results ConclusionIFOST-2014, Bangladesh 3. INTRODUCTIONA wind turbine is a rotating device which converts kinetic energy of windinto electrical energyHorizontal Axis Wind Turbine Vertical Axis Wind TurbineIFOST-2014, Bangladesh 4. OBJECTIVES Numerical modeling of a 2D Vertical Axis Wind Turbine CFD analysis of various performance parametersIFOST-2014, Bangladesh 5. BOUNDARY CONDITIONIFOST-2014, Bangladesh 6. CHOOSEN AIRFOILNACA 0018Chord length: 420mm High lift Better stall characteristics andlow dragIFOST-2014, Bangladesh 7. MESH GENERATION (Rotating Domain)IFOST-2014, Bangladesh 8. MESH GENERATION (Airfoil Section)IFOST-2014, Bangladesh 9. MESH GENERATION (Stationary Domain)IFOST-2014, Bangladesh 10. MESH GENERATION (Total Structure Domain) Nodes: 112929, Elements: 74532 Nature of the element: Quad The first cell height used such that they y+ values from the flow solutions did not exceed 1and the criterion is used to refine the mesh for a thickness equivalent to y+=30. The skewness of the cells such that the maximum is observed to be less than 0.6IFOST-2014, Bangladesh 11. SLIDING MESH TECHNIQUEIFOST-2014, Bangladesh 12. ASSUMPTIONS The incompressible, unsteady Reynolds Averaged Navier Stokes (URANS)equations are solved using finite volume method. The RNG k- model is adopted for the turbulence closure with standard wallfunctions on Near-wall treatment. A Sliding Mesh technique is used to rotate the rotor blade. Intensity of inlet and outlet turbulence is fixed to 5% and turbulence viscosityratio 10The unsteady Reynolds Average Navier Stokes equations are make out applyingthe green-gauss cell based gradient option. The SIMPLE pressure-based solver is selected having a second order implicittransient formulation for better result. All of the solution variables arecalculated with second order upwind discretization scheme.IFOST-2014, Bangladesh 13. MATHEMATICAL FORMULA Theoretical power, Pt=12 V3 Practical power, Pa = T Torque, =12CtV2 Angular velocity, =12 Power co-efficient, Cp= T/(V3 )Where, T= Torque (Nm)A= Swept area (m2)=2RlR= Rotor radius (m)V= Free stream velocity (m/s)= Angular velocity (rpm)= Density of air (kg/m3)= Tip speed ratioCt= Torque Co-efficientIFOST-2014, Bangladesh 14. MATHEMATICAL FORMULAIFOST-2014, Bangladesh 15. RESULTS2.00E+001.50E+001.00E+005.00E-010.00E+00-5.00E-01-1.00E+000 50 100 150 200 250 300 350 400Torque coefficient, CtAzimuthal angle,Figure 1: Torque coefficient vs Azimuthal angle for tip speed ratio (=2.0)6.00E+005.00E+004.00E+003.00E+002.00E+001.00E+000.00E+00-1.00E+00-2.00E+000 50 100 150 200 250 300 350 400Torque coefficient, CtAzimuthal angle,Figure 2: Torque coefficient vs Azimuthal angle for tip speed ratio (=4.5)IFOST-2014, Bangladesh 16. RESULTS (Contd)Figure 3: Power co-efficient vs Tip speed ratio for 9 m/s* Biadgo Mulugeta Asressa, Simonovi Aleksandarb, Komarov Draganb, Stupar Slobodanb Numerical and Analytical Investigationof Vertical Axis Wind Turbine, FME Transactions 2013, vol. 41, iss. 1, pp. 49-58IFOST-2014, Bangladesh 17. RESULTS (Contd)IFOST-2014, Bangladesh 18. CONCLUSION In this thesis, a 2-D numerical analysis has been completed using sliding meshtechnique, to predict the efficiency or power co-efficient of vertical axis windturbine From the performance curve, an optimum power co-efficient 0.34 is obtained attip speed ratio 4.5 This results may helpful for practical implementation of vertical axis windturbineIFOST-2014, Bangladesh 19. REFERENCES[1] Sathyajith, M, Wind Energy Fundamentals, Resource Analysis and Economics, Springer-VerlagBerlin Heidelberg, Netherlands, 2006.[2] Claessens, M.C., The Design and Testing of Airfoils for Application in Small Vertical Axis Windturbines, Delft University, November 2009.[3] Louis Angelo Danao, Jonathan Edwards, Okeoghene Eboibi , Robert Howell, A numericalinvestigation into the influence of unsteady wind on the performance and aerodynamics of avertical axis wind turbine, Proceedings of the World Congress on Engineering 2013 Vol III, WCE2013, July 3 - 5, 2013, London, U.K.[4] Asress Mulugeta Biadgo, Aleksandar Simonovic, Dragan Komarov, Slobodan Stupar, Numericaland Analytical Investigation of Vertical Axis Wind Turbine, FME Transactions (2013) 41, pp. 49-58.[5] Chao Li, Songye Zhu, You-lin Xu, Yiqing Xiao, 2.5D large eddy simulation of vertical axiswind turbine in consideration of high angle of attack flow, Renewable Energy, Volume 51, March 2013,pp 317-330.[6] Naveed Durrani, Haris Hameed, Hammad Rahman and Sajid Raza Chaudhry, A detailedAerodynamic Design and analysis of a 2D vertical axis wind turbine using sliding mesh in CFD,49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition4-7 January 2011, Orlando, Florida.[7] Marco Raciti Castelli, Stefano De Betta and Ernesto Benini, Effect of Blade Number on a Straight-Bladed Vertical-Axis Darreius Wind Turbine, World Academy of Science, Engineering and Technology61 2012.IFOST-2014, Bangladesh 20. Thanks To AllIFOST-2014, Bangladesh