A multi-fidelity approach for aerodynamics and aeroacoustics of vertical axis wind turbines

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Shubham, S., 2024. A multi-fidelity approach for aerodynamics and aeroacoustics of vertical axis wind turbines. PhD, Nottingham Trent University.

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Abstract

This thesis performs an in-depth exploration of Vertical Axis Wind Turbines (VAWTs), motivated by the urgent need to address global climate change through sustainable energy solutions. The research predominantly focuses on the aerodynamics and aeroacoustics of VAWTs using computational simulations. This thesis aims to contribute to the body of knowledge and state-of-the-art surrounding VAWTs, a less explored yet promising design of wind turbines, especially suitable for urban and floating offshore applications.

This thesis employs a multi-fidelity computational approach, leveraging both mid-fidelity and high-fidelity methods. The mid-fidelity Lifting Line Free Vortex Wake (LLFVW) method offers a balance between computational cost and accuracy. The high-fidelity Lattice Boltzmann/Very Large Eddy Simulation (LB-VLES) method provides detailed insights into the complex aerodynamics and aeroacoustics of VAWTs. These methodologies are implemented using the open-source software QBlade and the commercial software Dassault Systèmes SIMULIA PowerFLOW, respectively. The thesis examines VAWTs over a range of both design and operational parameters, including different number of blades, supporting structures (struts and central towers), tip speed ratio, and non-uniform inflow such as skewed inflow and VAWT clusters in parallel and tandem configurations.

The study highlights how the above-mentioned operational and design parameters significantly influence the force-field and flow-field of VAWTs and how the force-field mutually affects the flow-field. Additionally, the focus is on understanding how the VAWT force-field affects the pressure perturbations in the far-field and therefore, the noise generated. The study shows the potential of VAWT designs which can exhibit high power performance and low aerodynamic noise. Notably, the research underscores the increased power density achievable in VAWT clusters compared to standalone VAWTs.

A comparative analysis between mid-fidelity and high-fidelity methods demonstrates that while mid-fidelity methods accurately predict general performance trends, high-fidelity methods are essential for capturing the complex fluid dynamic interactions in the VAWT force-field and flow-field. This is found to be true when any combination of the design or operational parameters is used. The thesis concludes that VAWTs hold significant potential for urban and offshore applications, debunking common misconceptions about their inefficiency.

The thesis outlines numerous areas for future research, including exploring different VAWT blade shapes, assessing the impact of flow control devices, and understanding the influence of variable pitch on performance and aeroacoustics. Further investigations into the clustering of VAWTs and the use of different vortex methods for performance prediction are also recommended.

Item Type:

Thesis

Creators:

Shubham, S.

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