“Fast Track” Analysis of Small Wind Turbine Blade Performance

Abstract

Small wind turbines (SWTs) can be significantly sensitive to variances in the blade geometry shape when their operation in relatively low ranges of Reynolds numbers is considered. An SWT case study, where an existing wind turbine prototype was equipped with a redesigned blade set, to increase its aerodynamic efficiency, is presented. The geometry modification process was targeted at maximizing the turbine power coefficient in the presumed point of low Reynolds operation. The applied design and analysis methods included practical implementation of previously established “Fast Track” procedure for wind turbine development. A newly prepared blade geometry and a reference blade set were examined numerically and experimentally. Selected design and assessment processes were supposed to be low resource demanding, making them possibly highly applicable in renewable energy industry. Therefore, the numerical analysis of both geometries was based on BEM (blade element momentum theory) equations. The research was expanded by model validation in small-scale wind tunnel tests to provide detailed information on BEM data reliability in comparison to the results of the experiment. The small-scale analysis, performed in Reynolds numbers below 100,000, provided information sufficient for evaluation of the redesigned blade. Implementation of the geometry obtained throughout the proposed procedure increased the rotor’s maximum power coefficient by 10%.