Performance evaluation of H-type Darrieus VAWT with J-shaped blade geometry at variable pitch angles

Abstract

The most common vertical axis wind turbine are the S shaped Savonius and Darrieus turbine. The Savonius rotor is a simple, drag based wind turbine and has desirable self-starting capabilities, but due to low efficiency they are used in fewer applications, whereas the Darrieus rotors are more aerodynamically adept hence more efficient, however these turbines has an inability to self-start therefore rendered useless in areas with low wind velocity. A j-shaped blade with base geometry of NACA 2424 was developed by removing its pressure side from trailing edge to maximum camber; to induce self–starting capability of Savonius rotor and Darrieus rotors’ higher aerodynamic efficiency. Experimentation on J-shaped NACA 2424 VAWT against conventional Darrieus was conducted inside wind box at different mean wind velocities; 8.63 and 11.02 ms−1 with a turbulence intensity of 7.5 and 7.2%, respectively, over a range of angle of attack 0-12° with 3 degree interval. The J-shaped VAWT had better self-starting capabilities at all angle of attack, whereas the conventional Darrieus rotor had to be pushed to begin rotation. The results obtained shows that J-shape rotor had an average coefficient of performance of 15.38% whereas the Darrieus turbine had an average coefficient of performance of 10.72%. The J-shaped Darrieus rotor had average brake mechanical power of at 11.02 ms−1 is 50.30 watts while Darrieus turbine had 35.06 watts. The J-shaped Darrieus had 30% better COP than conventional Darrieus turbine.The most common vertical axis wind turbine are the S shaped Savonius and Darrieus turbine. The Savonius rotor is a simple, drag based wind turbine and has desirable self-starting capabilities, but due to low efficiency they are used in fewer applications, whereas the Darrieus rotors are more aerodynamically adept hence more efficient, however these turbines has an inability to self-start therefore rendered useless in areas with low wind velocity. A j-shaped blade with base geometry of NACA 2424 was developed by removing its pressure side from trailing edge to maximum camber; to induce self–starting capability of Savonius rotor and Darrieus rotors’ higher aerodynamic efficiency. Experimentation on J-shaped NACA 2424 VAWT against conventional Darrieus was conducted inside wind box at different mean wind velocities; 8.63 and 11.02 ms−1 with a turbulence intensity of 7.5 and 7.2%, respectively, over a range of angle of attack 0-12° with 3 degree interval. The J-shaped VAWT had better self-starting capabilitie...