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The aerodynamic performance of horizontal-axis wind turbines is strongly dependent on many parameters, among which the airfoil type and the blade geometry (mainly defined by the chord and the twist distributions) are considered the most critical ones. In this article, an approach giving the appropriate airfoil for a small wind turbine design was conducted by performing an aerodynamic improvement of the blade’s airfoil. First, a preliminary design of the rotor blades of a small wind turbine (11 kW) was conducted using the small wind turbine rotor design code. This preliminary approach was done for different airfoils, and it resulted in a maximum power coefficient of 0.40. Then, the aerodynamic efficiency of the wind turbine was improved by modifying the geometry of the airfoils. This technique targets the optimization of the lift-to-drag ratio (Cl/Cd) of the airfoil within a range of angles of attack. Also, a non-uniform rational B-spline approximation of the airfoil was adopted in order to reduce the number of the design variables of the optimization. This methodology determined the best airfoil for the design of a small wind turbine, and it gave an improved power coefficient of 0.42.

No abstract

This article presents a structural design and analysis of 11-kW small wind blades. The stress and the fatigue on the blades were computed using Simple Load Model from IEC 61400-2 standard, ANSYS nCode DesignLife, and FAST-MLife codes from the National Renewable Energy Laboratory. Simple Load Model gives good results in terms of stress analysis but overestimates fatigue damage on the blade. High safety factors imposed by the IEC 61400-2 standard, when full mechanical characterization of the blade material cannot be achieved, lead to heavy structures that impact the blade cost. For the same design, full computational analysis of the blade fatigue using FAST-MLife codes and the ANSYS nCode DesignLife revealed that the rotor blades will be safe against fatigue for a design lifetime of 20 years. This study shows that simple and reliable aeroelastic models are still needed for fatigue analysis of small wind blades.