An investigation into design optimization of vertical axis wind turbine

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Acknowledgement

I would take this opportunity to thank my research supervisor, family and friends for their support and guidance without which this research would not have been possible.

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I, [type your full first names and surname here], declare that the contents of this dissertation/thesis represent my own unaided work, and that the dissertation/thesis has not previously been submitted for academic examination towards any qualification. Furthermore, it represents my own opinions and not necessarily those of the University.

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Abstract

The purpose of this study is to introduce and demonstrate a fully automated process for optimizing the airfoil cross-section of a vertical axis wind turbine (VAWT). The objective is to maximize the torque while enforcing typical wind turbine design constraints such as tip speed ratio, solidity, and blade profile. By fixing the tip speed ratio and solidity of the wind turbine, there exists an airfoil cross-section for which the torque can be maximized, requiring the development of an iterative design system. The design system required to maximize torque incorporates rapid geometry generation and automated hybrid mesh generation tools with viscous, unsteady computational fluid dynamics (CFD) simulation software. The flexibility and automation of the modular design and simulation system allows for it to easily be coupled with a parallel differential evolution algorithm used to obtain an optimized blade design that maximizes the efficiency of the wind turbine.

Table of Contents

CHAPTER 1: INTRODUCTION6

Background6

Theoretical framework7

Problem Statement8

Aims and Objectives8

CHAPTER 2: LITERATIRE REVIEW9

Vertical axis wind turbine (VAWT)9

Wind Turbine Types10

Horizontal Axis Wind Turbines11

Vertical Axis Wind Turbines14

Advantages of vertical axis wind turbines17

Disadvantages of vertical axis wind turbines18

Vertical Axis Wind Turbine Performance18

Ideal Performance and the Betz Limit18

Wind Speed and Tip Speed Ratio19

Computational Modeling20

Effects of roughness22

Geometry Creation22

CHAPTER 3: COMPUTATIONAL METHODOLOGY24

Introduction24

Pre-processing25

Requirements25

Unique Modular Design25

Directory Structure27

Complete Automation28

Parametric Studies and Optimization28

CHAPTER 4: ANALYSIS AND DISCUSSION30

Grid Dependency Studies30

Structured Grid Topology31

Hybrid Grid Topology34

Grid Independent Solution36

Baseline Geometry39

Baseline Performance40

Case 144

Optimization Results44

Case 248

Optimization Results48

CHAPTER 5: CONCLUSION51

REFERENCES53

CHAPTER 1: INTRODUCTION

Background

Wind is everywhere. As long as the Earth continues to provide the right conditions, it will remain that way. All it takes is a difference in pressure to get a mass of air moving. This movement of air from areas of high pressure to areas of low pressure is what generates wind. Because this mass of air is moving, it has energy, renewable energy that has been used to provide thrust to sailboats and ships crossing the oceans, to windmills used to pump water for irrigation or grinding up grain. Even today, wind is still harnessed for much the same reason as it was thousands of years ago, but something it can provide in today's day and age is electricity. Today, only a small fraction of the world's electricity is generated by wind, however, demand for this renewable energy resource will continue to increase with the depletion of fossil fuels (Sane, 2001, pp. 2607).

As the world continues to use up non-renewable energy resources, wind energy will continue to gain popularity. A new market in wind energy technology has emerged that has the means of efficiently transforming ...