الفهرس 
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Abstract
The power generation by a horizontal axis wind turbine (HAWT) is considered to be at the forefront of technology due to its reliability and cost effectiveness. However, the power coefficient of wind turbine is not at the desired level due to the insufficient extraction of power from the wind by the turbine blades. The turbine blades experience an undesirable phenomenon of the tip of the blade known as vortex due to the pressure difference on the surface of the blades. The presence of the vortex impairs the performance of the turbine blades as it reduces the Lift-to-Drag ratio. Hence, the objective of the present investigation is to study the performance of Small Capacity Horizontal Axis Wind Turbine (SSHAWT). Blade Element Momentum (BEM)
calculations are first used to get suitable design of the turbine blade. Further, experimental measurements and numerical simulations are performed. The numerical results presented in this study are based on the three-dimensional incompressible Unsteady Reynolds-Average Navier-Stokes (URANS) equations that are solved by employing ANSYS Fluent. The turbulence model used in this study is the SST k–ω
turbulence model based on the recommendations of different publications. Grid independence study is performed to know the effect of grid resolution on the power
coefficient (Cp) for the rotor at different tip speed ratios (λ). Validation of the numerical
methodology is performed using the present experimental data and that available in the literature. It is aimed to install a simple and efficient design of SSHAWT and verify its performance experimentally. For performing the experimental work, a free air jet test rig was built at the laboratory of advanced fluid mechanics of the Faculty of Engineering, Menoufia University.
The proposed rotor models are fabricated, tested, and compared. The first one is a classical rotor with non-linear chord and twist distributions, and the second one is a new linearized rotor design. It is worth mentioning that; linearization of the chord with twisting is practical solution to minimize the manufacturing cost of the rotor blades. A thin airfoil E216 is selected based on its maximum Lift-to-Drag ratio of 68.543, at Reynolds number of 105 , to design the rotor blades. The rotor diameter of both designs is 1 m, with three blades. The comparison between the two designs is verified experimentally, at different air speeds of 5, 6, 8, and 10 m/s. Further, measurements are conducted at blade pitching angle of 0, 3, and -3 degrees. It is found that, the new
proposed linear design of the rotor blades has efficient performance, with maximum power coefficient of 0.426 at tip speed ratio 5.1 and wind speed 10 m/s, with performance approaching that achieved by non-linear blades. Moreover, there is a significant reduction in the blade size of the new linear design compared with the classical design, which consequently reduces the blade weight and hence the cost. The experimental results
obtained in the present work show higher starting torque and extended operating range of the linearized model at lower wind speed, than the classical model.
The performance of (SSHAWT) rotor with different winglet curvatures is also studied numerically. Rotors with two curvature types (convex and concave) based on the wind direction, of forward (convex) angles 5ᵒ , 10ᵒ
, 15ᵒ , 20ᵒ , 30ᵒ and 45ᵒ and backward (concave) angles -5 ᵒ ,-10ᵒ and -15ᵒ
are investigated. Further, three curvature positions of r/R=0.8, 0.9
and 0.95 are studied. The numerical simulations are performed on rotors of radius 0.5 m at different wind speeds. The results are compared with straight rotor of linear profiles of chord and twist, which is considered as base rotor. It is found that the turbine with forward curvature of 5 degrees and r/R =0.9 has the highest power coefficient compared with the other rotors. This proposed rotor leads also to a reduction in the axial thrust by
about 12.5% compared with the base rotor at peak performance. The flow behavior in terms of streamline contours and axial velocity profiles is also presented and discussed.