Wind energy is one of the fastest growing alternative energy resources being taped into worldwide. Vertical axis Darrieus ‘H’ type lift turbines have the potential to compete effectively with the more widely used conventional horizontal axis wind turbines. However, a disadvantage is when the rotor is stationary, no net rotational force arises, even at high wind speed. The rotor must already be spinning to generate torque and the design is normally not self-starting. In this study a hybrid Darrieus ‘H’ type lift turbine was designed to operate as a self-starting drag type turbine at low rotational speed. With increasing rotational velocity the centrifugal force converted the drag type blades to full symmetrical airfoil sections making the turbine lift type. Design calculations, construction and testing of a two-blade prototype with 43 cm long blades, 14 cm wide, which formed a symmetrical airfoil of NACA 0018 profile when closed. The diameter for the turbine was 1.448 m and tests were conducted at six pitch angles with respect to the closed blade section (0°, 15°, 22.5°, 30°, 37.5° and 45°). Test results showed that the wind turbine was self-starting and the shaft speed increased linearly with wind speed at all angles of attack for moderate wind speed up to 10 m/s. However, the rate of change in shaft speed with wind speed showed an increase from 0° angle of attack to a critical 37.5° angle of attack and then decreased at 45° angle of attack. This observation is consistent with airfoil theory that greater drag forces exist at smaller angles of attack. A similar trend was observed for shaft power and turbine efficiency with maximum values of 49.5 W and 24%, respectively, at a wind speed of 8.29 m/s for the 37.5° angle of attack. The tip speed ratio increased from a minimum of 0.83 at 0° to a maximum of 2.66 at 37.5° and then decreased at 45°. This indicated drag type operation (t.s.r. < 1) at small angle of attack and lift type operation (t.s.r. > 1) at higher angle of attack. This trend was consistent with theory as the drag force decreased the aerodynamic lift force increased with increasing attack angle, causing the blade speed to exceed that of the wind speed.
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ASME 2007 Energy Sustainability Conference
July 27–30, 2007
Long Beach, California, USA
Conference Sponsors:
- Solar Energy Division and Advanced Energy Systems Division
ISBN:
0-7918-4797-7
PROCEEDINGS PAPER
Self-Starting Hybrid ‘H’ Type Wind Turbine
Krishpersad Manohar,
Krishpersad Manohar
University of the West Indies, St. Augustine, Trinidad, Trinidad and Tobago
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Annil Rampartap,
Annil Rampartap
University of the West Indies, St. Augustine, Trinidad, Trinidad and Tobago
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Rikhi Ramkissoon
Rikhi Ramkissoon
University of the West Indies, St. Augustine, Trinidad, Trinidad and Tobago
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Krishpersad Manohar
University of the West Indies, St. Augustine, Trinidad, Trinidad and Tobago
Annil Rampartap
University of the West Indies, St. Augustine, Trinidad, Trinidad and Tobago
Rikhi Ramkissoon
University of the West Indies, St. Augustine, Trinidad, Trinidad and Tobago
Paper No:
ES2007-36187, pp. 1139-1146; 8 pages
Published Online:
February 24, 2009
Citation
Manohar, K, Rampartap, A, & Ramkissoon, R. "Self-Starting Hybrid ‘H’ Type Wind Turbine." Proceedings of the ASME 2007 Energy Sustainability Conference. ASME 2007 Energy Sustainability Conference. Long Beach, California, USA. July 27–30, 2007. pp. 1139-1146. ASME. https://doi.org/10.1115/ES2007-36187
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