الفهرس 
Aerodynamic Investigation for the Effect of Blade Geometry on the Performance of HAWT
Chapter 1: IntroductionOnly 14 pages are availabe for public view
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Abstract
Small-scale horizontal axis wind turbines (SSHAWT) have recently gained more interest due to fuel shortages and environmental issues. In residential areas, the focus is on domestic SSHAWTs rather than large-scale horizontal axis wind turbines (LSHAWTs). In wind farms, LSHAWTs are installed in large numbers due to the availability of wasted space and are exploited in the link to the electric grid. These LSHAWTs usually operate at relatively high wind velocity, reaching more than 10 m/s. Nevertheless, these velocities are not easy to be achieved in residential areas due to the surrounding areas and the wind boundary layer. As a result, LSHAWTs are unsuited for use in residential regions.Generally, SSHAWTs are installed close to the ground in the wind boundary layer, where the velocity is relatively small. The test of the scale model is most popular in previous studies and used dimensional analysis to represent a full scale, but the similarity is still questionable. So, this study aims to evaluate the performance of a full-scale commercial SSHAWT and to modify rotor design based on wind velocity in the field. The experimental measurements are performed to examine a commercial 1 kW SSHAWT, which was designed at a rated velocity of about 8 m/s. The CFD and analytical calculations using Q-blade are performed as well to understand flow characteristics and to verify the experimental measurements. The numerical results presented in this study are based on the three-dimensional incompressible Steady Reynolds-Average Navier-Stokes (RANS) equations that are solved by employing ANSYS Fluent. The SST k–ω turbulence model is used. In the experimental procedure, the test of the wind turbine with a permanent magnet synchronous generator is carried out by using nine axial fans working as open grid fans in the Benha Faculty of Engineering wind laboratory. The commercial blade profile consists of three airfoils S835 at the hub, S833 at the root, and S834 at the tip. The maximum Lift-to-Drag ratio of the commercial rotor is about 45.6, at a Reynolds number of 105. The experimental tests are carried out at 4, 5, and 6 m/s. The experimental results showed that at a wind velocity of 5 and 6 m/s, the highest generated power is 163.9 and 306 W corresponding to power coefficients of 0.255 and 0.28 when the AC voltage of the generator is 24.4 and 37.76 V, the DC voltage after rectified 22 and 34 V, and the load current 7.45 and 9 A, respectively. Also, the numerical calculations using CFD and the analytical results using Q-blade agreed well with the experimental results.
Then the available wind velocity is measured on the Obour campus at Benha university, and the average velocity was found to be 4 m/s. Therefore, a more appropriate rotor is designed based on field velocity. The Q-blade software is first used to design the new rotor at the same radius as the commercial rotor. The new rotor that consists of airfoil geometry SG6040 and SG6043 which is selected based on its maximum Lift-to-Drag ratio of 65.5 at an angle of attack of 7° and a Reynolds number of 105. Furthermore, the CFD calculations are used to test the new rotor. The results clarify that the blade loading for the SG-rotor is higher than the S-rotor. Also, the flow separation phenomena manifest more strongly for the S-rotor than the SG-rotor so the SG-rotor is more stable than the S-rotor. Finally, for the SG-rotor, the maximum blade’s power coefficient is enhanced by more than 45% compared to the commercial rotor.