Optimization of Blade Mount Point and Preset Pitch in a Conventional Small Vertical Axis Wind Turbine
Posted: 21 Jun 2019 Last revised: 30 Jun 2019
Date Written: June 17, 2019
Among the several categories of wind generators, small wind turbines have gained more and more interest for their excellent adaptability to the urban environment in terms of visual impact and noise pollution. Being axisymmetric, they are omnidirectional turbines, which respond well to changes in wind direction. To analyze the complexity of unsteady aerodynamic flow associated with a small conventional vertical axis wind turbine (VAWT) functioning, computational fluid dynamics (CFD) is an attractive and powerful method. The numerical model has been accomplished by means of CFD analysis by solving Unsteady Reynolds Average Navier-Stokes (URANS) equation. A rigorous parametric study of choosing a right turbulence model for solving URANS (unsteady RNG k-ε turbulence model) equation, mesh dependency analysis and the optimum time step is comprehended using sliding mesh technique in ANSYS Fluent 19.1. After choosing the right parameters, the benchmark is performed using wind tunnel flow field measurement. Following that the flow fields, a series of parametric studies have been conducted to investigate the impact of geometrical parameters. In this study, the geometrical optimization is focused on the impact of blade pre-set pitch and blade mount point offset. This study shows that the performance of the turbine can increase up to 60% by using appropriate blade offset and pre-set pitch. Another parameter investigated in this research is blade twist. The results compare well to the preliminary studies and indicate a decrease of up to 65% of amplitude and increase of up to 45% of performance coefficient could be achieved through the use of properly designed, bend twist vertical blades.
Keywords: VAWT, CFD, Blade Mount Point, Blade Pre-Set Pitch
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