Performance Characteristics of an Orthopter-Type Vertical Axis Wind Turbine in Shear Flows

Abstract

To properly conduct a micro-siting of an orthopter-type vertical axis wind turbine (O-VAWT) in the built environment, this study investigated the effects of horizontal shear flow on the power performance characteristics of an O-VAWT by performing wind tunnel experiments and computational fluid dynamics (CFD) simulations. A uniform flow and two types of shear flow (advancing side faster shear flow (ASF-SF) and retreating side faster shear flow (RSF-SF)) were employed as the approaching flow to the O-VAWT. The ASF-SF had a higher velocity on the advancing side of the rotor. The RSF-SF had a higher velocity on the retreating side of the rotor. For each type of shear flow, three shear strengths (Γ = 0.28, 0.40 and 0.51) were set. In the ASF-SF cases, the power coefficients (Cp) were significantly higher than the uniform flow case at all tip speed ratios (λ) and increased with Γ. In the RSF-SF cases, CP increased with Γ. However, when Γ = 0.28, the CP was lower than the uniform flow case at all λ. When Γ = 0.51, the CP was higher than the uniform flow case except at low λ; however, it was lower than the ASF-SF case with Γ = 0.28. The causes of the features of CP were discussed through the analysis of the variation of blade torque coefficient, its rotor-revolution component and its blade-rotation component with azimuthal angle by using the CFD results for flow fields (i.e., horizontal velocity vectors, pressure and vorticity). These results indicate that a location where ASF-SFs with high Γ values dominantly occur is ideal for installing the O-VAWT.

Special Issue on Wind Turbine Aerodynamics II

“…There is one paper dealing with a study of orthopter-type vertical axis wind turbine (O-VAWT) concept [22]. The study by Wijayanto et al [23] investigated the effects of horizontal shear flow on the power performance characteristics of an O-VAWT by performing wind tunnel experiments and computational fluid dynamics (CFD) simulations. A uniform flow and two types of shear flow (advancing side faster shear flow (ASF-SF) and retreating side faster shear flow (RSF-SF)) were employed as the approaching flow to the O-VAWT.…”

Analysis of a Nature-Inspired Shape for a Vertical Axis Wind Turbine

“…The growing worldwide demand for wind energy leads to the necessity of obtaining a more efficient use of wind that cannot be employed by large HAWTs. To this end, VAWTs are aimed at low scale applications, especially urban environments with poor wind conditions [3][4][5][6]. The exploitation of these winds together with the winds exploited by large wind turbines may considerably increase the global wind energy production.…”

Optimization of a Nature-Inspired Shape for a Vertical Axis Wind Turbine through a Numerical Model and an Artificial Neural Network

“…On the other hand, VAWTs are less common but also interesting due to their capacity to capture wind from all directions and their acceptable performance under poor wind conditions. These characteristics make VAWTs appropriate for small power generation applications, especially in urban environments [9]. VAWTs are basically categorized into Darrieus (based on lift) and Savonius (based on drag).…”