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Title: A computational fluid dynamics investigation of a vertical axis augmented wind turbine designed for the built environment
Author: Nobile, Rosario
ISNI:       0000 0004 5357 7639
Awarding Body: University of Reading
Current Institution: University of Reading
Date of Award: 2014
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In recent years, there has been an increasing interest in vertical axis wind turbines (VA WTs); as they show a number of benefits when installed in the built environment. Nevertheless, VAWTs still suffer from: complex aerodynamics; dynamic stall and hence lower efficiency. Additionally, when they are integrated in the built environment the challenges are low/zero starting torque, noise and vibrations, visual impact and blade safety. In response to these needs, a vertical axis augmented wind turbine (A WT) has been developed, which is composed of a stator and a rotor. In this thesis, the aerodynamics of the vertical axis augmented wind turbine (A WT) was examined by employing a Computational Fluid Dynamics (CFD) tool. The main focus was on the 2D and 3D simulations of the vertical axis augmented wind turbine (A WT). In the 2D investigation, an open rotor was analysed in order to select the most appropriate mesh, turbulence model, and timestep. Successively, the rotor was combined with a stator and the results compared to the open rotor. The development of dynamic stall in both open and augmented rotors was also examined. The CFD results of the open rotor were validated using experimental data. In the 3D stator, the focus was to understand how the stator blades, the diameter and the conical surfaces could affect the flow. In the 3D open and augmented rotors, the results were compared to the 2D cases in order to evaluate similarities and dissimilarities. The 2D investigation has shown that the forces generated on the blades of an open rotor were dependent on the mesh resolution and turbulence model selected, while the timestep had small impact. The introduction of an augmenter has the potential to increase the power coefficient by 1.35 times when compared to the open rotor. However, the stator blade and conical surface orientation were found to affect the performance of the A WT, while changing the rotor blade orientation had small impact. The generation of dynamic stall was detected at low tip speed ratios (TSRs), but the turbulence model could affect its formation. The CFD results of the open rotor were found to be in good agreement with experimental data. In the 3D investigation, the stator was found to guide and accelerate the flow, but the orientation of both conical surface and stator blade play an important role. The 3D simulations, related to open and augmented rotor, were found to have similarities and dissimilarities when compared to the 2D. This research has developed a modelling technique, which could help with the further development of the AWT.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (D.Eng.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available