| Summary: | The horizontal-axis-wind-turbine (HAWT) is popular in the wind power industry nowadays due to its high power extraction capability. However, the HAWT has some complications due to high turbulent, low speed and changing direction of wind, which inhibits its full performance. Some vertical-axis-wind-turbine (VAWT) designs were able to function well under these wind conditions but they usually produce less power compared to HAWT. Thus, a new type of wind turbine design is proposed to overcome the weaknesses of HAWT and VAWT namely the cross-axis-wind-turbine (CAWT). The CAWT has three vertical and six horizontal blades, which interacts with horizontal and vertical wind. The vertical wind is generated by introducing a deflector or an omni-directional shroud to direct the oncoming horizontal wind towards the horizontal blades. The shroud consists of stacked ring-like deflecting planes supported by vertical webs and an inverted funnel-shaped base. It was designed to produce vertical wind components from any horizontal wind direction. The performance of the shroud was investigated by using a computational fluid dynamics (CFD) software, which showed significant vertical wind component located at the top of the proposed shroud. Experiments using deflectors to guide the oncoming airflow upward were designed to test the CAWT performance with various inclination angles (from 30 to 45°, with 5º increment). The experiments were also conducted with different pitch angles to identify the characteristics of the horizontal blades of the CAWT. A conventional H-rotor VAWT was tested under the same experimental conditions for benchmarking purposes. The results showed that the CAWT produced significant improvements in power output and rotational speed performance compared to the VAWT. It was found that the CAWT’s peak power coefficients (integrated with the 45° deflector) were increased significantly by 103 to 175 % at different tip speed ratios for various horizontal blade pitch angles. The study showed that the proposed CAWT was able to achieve maximum RPM of up to 112% higher than that of the VAWT counterpart as well as better starting behaviour. These preliminary findings show the potential of CAWT for future applications in many locations, creating significant opportunities for wind energy devices.
|
|---|