Prova de conceito de controle passivo de ângulo de arfagem em pás de microgeradores eólicos

Abstract

Research and technology available for small wind turbines is still dependent on further development in order to meet the varied demands brought by the applications for which they are used. Taking into account the importance of microgenerators for off-grid applications in Brazil, this term paper was developed as a proof of concept for the passive pitch angle control for small wind turbine blades. This is proposed to be accomplished through aeroelastic tailoring of laminate composite material, so as to induce anisotropic structural behavior and introduce bend-twist coupling effect taking advantage of the aerodynamic loads to which the blade is subjected in operation. With a pre-established blade geometry, the behavior of different lay-ups in relation to their performance in extracting wind energy is evaluated in an iterative process between determining the aerodynamic loads and the twist of the blade that followed. The loads are obtained through the Blade Element Momentum – Theory (BEMT), coupled with the hypothesis that thin foil theory applies, with a programmed Matlab script, and the deflection is evaluated in several points along the span of the blade by using the ACP (ANSYS Composite PrepPost) module in the ANSYS software upon the definition of a material and a lay-up, and with the application of pressure calculated based on the aerodynamic loads obtained. It is possible to conclude that, for certain lamination parameters, a bend-twist coupling can be obtained such that the performance of the turbine, evaluated by means of its power coefficient, is increased in relation to a turbine with isotropic behaving blades (with no bend-twist coupling).