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ENCIT 2020
18th Brazilian Congress of Thermal Sciences and Engineering
DARRIEUS H-VAWT PERFORMANCE ANALYSIS USING FINITE VOLUME METHOD AND MULTIPLE STREAMTUBE
Submission Author:
Larissa Pontes , RN
Co-Authors:
Larissa Pontes, Jakson Junior, Joao Alves de Lima
Presenter: Jakson Junior
doi://10.26678/ABCM.ENCIT2020.CIT20-0551
Abstract
Wind energy has become a promising source of renewable energy. In particular, due to their low performance, vertical axis wind turbines (VAWT) are less used than horizontal axis wind turbines (HAWT). Nonetheless, they are suitable for unconventional installation areas, as they present lower variations in the power coefficient, lower noise emission and satisfactory reliability. In this work, the performance of an H-VAWT is evaluated using two approaches: the classical multiple streamtubes method (DART Code) and a computational fluid dynamic analysis (CFD) based on the finite volume method (ANSYS Fluent code). The former is used to obtain an initial rotor geometry that meets the power requirement for a given local wind condition and the last one is employed to verify this geometry. Numerical convergence was attained for time steps to which ≤ 1.8° and meshes with divisions on the edges of the airfoil Nd ≥ 300. For the DART code, the maximum power coefficient Cpmax = 0.29 was obtained for a tip speed ratio = 3.4, while with the Fluent code, Cpmax = 0.24 for = 3.0. The performance curves (Cp x ) showed similar behavior, a negative power coefficient at low tip speed ratios ( < 2.8) and a maximum power coefficient at similar tip speed ratios. The local power coefficient at the tip speed ration for maximum power coefficient ( = 3.0) showed that in some regions it exceeds the Betz’s limit, so this behavior is studied in the literature. The pressure gradient analysis showed why the power coefficient is negative for < 2.8, making the rotor unable to self-start.
Keywords
wind turbine, H-VAWT, Multiple Streamtubes, Finite volume method
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