IMPROVEMENT OF HYBRID VERTICAL AXIS WIND TURBINE PERFORMANCE FOR LOW WIND SPEED CONDITION

Abstract

Vertical-axis wind turbine (VAWT) as a power generator has shown great interest in research design to improve operational efficiency and enhance self-starting capability. Currently, Darrieus rotor is known for generating high torque at low wind speed condition from  any direction indicating that Darrieus type wind turbine is excellent in electricity generator. However, Darrieus rotor suffers from poor self-starting capability and such wind turbine requires external power start-up. As a promising solution, dual stage Scoop Harmony combined with three-bladed NACA 0018 Darrieus rotor: D-rotor, H-rotor and Helix-rotor has been proposed to improve these limitations. Scoop Harmony is a drag-based turbine, assist to generate torque but received lesser attention compared to Savonius rotor. A proposed CAD wind turbine model was designed and fabricated using a 3D printer to study the effect of combined Darrieus and Scoop Harmony rotor on obtaining the tip speed ratio, torque and power coefficient, . All rotors have a similar chord length, solidity, radius and height dimension. During test run, wind speed operation was varied from 0 to 8m/s, following the wind speed conditions in Malaysia. Results shows that D-rotor with Scoop Harmony gives the best performance compared to Helix rotor and H-rotor. The tip speed ratio for D-rotor can reach up to 12% higher than Helix-rotor and 53.5% higher than H-rotor at a wind speed of 8 m/s. For the torque rate, D-rotor has a 76% higher torque output than H-rotor and 25% higher than Helix-rotor. Meanwhile for  D-rotor generates 23% and 75% higher compared to Helix rotor and H-rotor. However, D-rotor suffers from slower start-up compared to Helix-rotor when the starting torque occurred at 4 m/s compared to the Helix-rotor which is able to start up at only 3 m/s.