الفهرس 
CHAPTER 1 INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Wind energy is the fastest growing energy in the world today. Vertical axis wind turbine (VAWT) is an effective way to benefit from this energy. So, The objective of the present work is to enhance the performance of vertical axis wind turbines VAWTs (Darrieus turbine) in order to operate efficiently at low wind speeds and improve their performance and self-starting characteristics. This has been achieved by both numerical and experimental investigations. The numerical results presented in this study are based on solving the two-dimensional incompressible unsteady Reynolds-Averaged Navier-Stokes (RANS) equations using ANSYS-FLUENT 15. Three different turbulence models are adapted in this study, which are, the realizable k–ε, the SST k–ω and Transition SST k–ω. Validation of the numerical methodology is performed using the available experimental data from the literature. The CFD predictions of the power coefficient are well compared to the experimental work. Furthermore, the CFD results indicated that the transition SST turbulence model gives the best predictions of the experimental power coefficient. Therefore, the simulation is extended using the transition SST k–ω turbulence model as a suitable turbulence model for further predictions of different non-measured data.