Development of a Micro Horizontal Axis Wind Turbine Blade for the Semi-Arid Region of Nigeria

Abstract

AbstractThe semi-arid region of Nigeria has exceptionally reliable wind energy resource that is not fully exploited. This resource is associated with stochastic high wind speed phenomena, which are destructive to wind energy conversion systems not specifically designed for the region. In wind turbines, the component that is most affected by stochastic wind is the blade. In this work a horizontal axis wind turbine (HAWT) blade is developed for the region based on 32 years correlated wind data obtained from the Nigerian Metrological Agency. The blade airfoil is developed based on a modified National Adversary Committee on Aeronautics (NACA) 4412 airfoil profile. The airfoil was modified using the Design Foil Workshop CAD code, and optimal lift to drag coefficient ratio and angle of attack are determined. Other blade design parameters such as the blade chord length, lift force, drag force, and wind relative angle are determined using the Blade Element Momentum Theory (BEM). The lift to drag coefficient ratio of 124 is recorded at an 8 degree angle of attack and 3 × 106 Reynolds number. Based on the modified blade airfoil with a chord length of 0.24 m, other blade design parameters are determined, which include lift force determined to be 28.611 N, drag force determined to be 0.277, and wind relative angle determined to be 48. Based on this design, a model of the blade is developed on a scale factor of 1:11 and its performance test in a wind tunnel. The result of the wind tunnel test shows that from the available energy of 151.52 Watts in the wind at speed of 6 m/s, the blade extracted 33% (50 Watts) of it. Moreover based on the design parameter performance of the HAWT blade is numerically predicted using the Computational Fluid Dynamics (CFD) code ANSYS Fluent 6.18. The CFD result shows that a power output of 51 Watts can be generated at a wind speed of 6 m/s. The CFD result also shows that the modified blade airfoil has satisfied the Bernoulli’s effect and Newton’s Third Law. However, 2.5 m/s has also been established to be the cut-in wind speed in both experimental and numerical analysis. The numerical and experimental results were tested for validation using the F-test statistical tool in Microsoft Excel. The test result shows that there is no significant difference between the two results with a test value of 0.98400234 and this shows that there was an agreement between the results.KeywordsHAWT bladeCFDAngle of attackWind speed