The earlier EU-sponsored project MEXICO (model experiments in controlled conditions) provided a huge database for flows past an experimental rotor in standard and yaw conditions. This study aims to determine the eligibility of different models under various conditions by using the MEXICO data. The main purpose of this project is to improve the BEM technique for yawed flows by using the new yaw model. Additionally, the BEM technique with new yaw model is compared with the CFD and measurement results. The Glauert’s yaw model is also applied in BEM model to compare the effectiveness of the new yaw model. It is proved that the CFD technique is still better than the BEM technique except at the high yaw and wind conditions. Furthermore, new yaw model is favored against Glauert’s yaw model. This project also aims to implement the new tip loss correction model in the BEM code and the results are validated with the CFD results.

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Thesis (MScEng (Department of Mechanical and Mechatronic Engineering))--Stellenbosch University, 2006. / ENGLISH ABSTRACT: Wind conditions in South Africa determine the need for a small-scale wind turbine to produce useable power at windspeeds below 7m/s. In this project, a range of windspeeds, within which optimal performance o the wind turbine is expected, was selected. The optimal performance was assessed in terms of the Coefficient of Power(Cp), which rates the turbines blade's ability to extract energy form the avalible wind stream. The optimisation methods employed allowed a means of tackling the multi-variable problem such that the aerodynamic characteristics of the blade were ideal throughout the wind speed range. The design problem was broken down into a two-dimensional optimisaion of the airfoils used at the radial stations, and a three-dimensional optimisation of the geometric features of the wind rotor. by means of blending various standard airfoil profiles, a new profile was created at each radial station. XFOIL was used for the two-dimensional analysis of these airfoils. Three-dimensional optimisn involved representation of the rotor as a simplified model and use of the Blade Element Momentum(BEM) method for analysis. an existimg turbine blade, on which the design specifications were modelled, was further used for comparative purposes throughout the project. The resulting blade design offers substantial improvements on the reference design. The application of optimisation methods has successfully aided the creation of a wind turbine blade with consistent peak performance over a range of design prints. / Sponsored by the Centre for Renewable and Sustainable Energy Studies, Stellenbosch University