CFD Analysis of the Characteristics of a Shrouded Turbine

Inhaltsangabe:Abstract:Wind energy is an increasingly import source of renewable clean energy. In spite of this only the methods and the materials of construction have improved over time while the basic working principle of the wind turbine is still the same as it was centuries ago. In this thesis we have increased the power of a wind turbine by a factor of 4 in a fluid dynamic simulation using a very simple external shroud system. We have also extended the theory of wind turbines (limit of Betz) to include this new kind of device and show why past attempts to augment the power of a wind turbine by means of shroud systems have failed. A detailed analysis of the device and its functioning principle is presented in this thesis - optimization studies need to be done in the future.Inhaltsverzeichnis:Table of Contents:AbstractIIndexIIList of FiguresIVList of SymbolsVIIntroduction11.Theory of Wind Turbines51.1Introduction51.2The Betz Law61.3Aerodynamics of the rotor131.4Rotor Power Characteristics181.5Number of Rotor Blades201.6Horizontal Axis Wind Turbines (HAWT)221.7Shrouded / Ducted Wind Turbines281.7.1Ducted Rotor291.7.2Turbine with a Diffuser Duct292.Methodology332.1Introduction332.2Computational Domain342.3Computational Code412.3.1Conservation Equations422.3.2K-Epsilon Turbulence Model432.3.3Discretization of the Conservation Equations452.4MFR - Multiple Frame of Reference452.5Parallel Processing462.6Simulations473.Results483.1Introduction483.2Conventional Turbine493.2.1Velocity Field493.2.2Static Pressure Field523.2.3Total Pressure Field533.2.4Power of the Conventional Turbine553.2.5Energy and Momentum Transfer573.3Shrouded Turbine593.3.1Velocity Field593.3.2Static Pressure Field623.3.3Total Pressure Field633.3.4Power of the Shrouded Turbine653.3.5Energy and Momentum Transfer663.3.6The Betz Limit683.3.7Cross Check Analysis with Traditional Shrouded Turbines69Conclusions72Bibliography73Acknowledgments