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Introduction
Published in Thomas Corke, Robert Nelson, Wind Energy Design, 2018
The modern era of wind turbine design reflects the appreciation gained in aerodynamics that also drove the development of modern aircraft. The designs of the early 20th century involved both vertical and horizontal axis wind turbines. These were generally aimed at generating electricity. The vertical axis wind turbines (VAWT) employed either aerodynamic lift or drag to extract energy from the wind. In 1931, a French engineer named Georges Jean Marie Darrieus patented the Darrieus wind turbine. The photograph in Figure 1.14 shows an example of an early Darrieus design. It consists of a two curved rotors that have an airfoil section shape. The driving force that moves the rotors is aerodynamic lift. The vertical axis had the benefit of locating the electric generator on the ground. However the large loads at the base often required the use of guy wires for support. The largest built Darrieus wind tur‐ bine is the Eole turbine located in Cap‐Chat, Quebec Canada that is shown in the photograph in Figure 1.15. The turbine is 100 m. tall and 60 m. wide. It is used only occasionally because of structural fatigue issues.
Synthesis of energy harvesting, structural control and health monitoring
Published in You-Lin Xu, Jia He, Smart Civil Structures, 2017
A series of full-scale field tests were conducted on a group of 10-m VAWTs under natural wind conditions during summer 2010 (Dabiri 2010). The field test results showed that power densities of a greater order of magnitude could potentially be achieved by appropriately arranging VAWTs in layouts that enable them to extract energy from adjacent wakes and upwind farms. This improved performance did not require higher individual wind turbine efficiency, but only closer wind turbine spacing and a sufficient vertical flux of turbulence kinetic energy from the atmospheric surface layer. The National Research Council of Canada (NRC) also performed field tests of large-scale VAWTs and the test data were obtained from a 24-m VAWT operating at 29.4 rpm (Penna and Kuzina 1984). Sandia National Laboratories (SNL) designed and built a 17-m VAWT with and without struts. Worstell (1981) reported that a maximum rotor power coefficient of 0.467 could be achieved from this VAWT operating at 38.7 rpm. Moreover, the field measurements of a 34-m VAWT were conducted over three years by SNL to assess its structural dynamics, aerodynamics, fatigue and controls (Ashwill 1992). The field measurements of the largest VAWT, the curved-blade Darrieus Éole turbine as shown in Figure 17.2a, demonstrated that the maximum power output can exceed 1.3 MW at about 14.7 m/s (11.35 rpm) (Richards 1987). This turbine operated successfully for over 30,000 h during a five-year period from March 1988 and produced over 12 GW of electricity.
Wind Turbines
Published in V. Dakshina Murty, Turbomachinery, 2018
As described earlier, VAWT are wind turbines that generate power from rotors that are vertical. In such machines, since the torque-generating surfaces move in the wind direction, the blade speeds are always less than wind speed. Consequently, the speeds of VAWT are lower than those of the horizontal axis-type turbines. Also, during part of the revolution, the motion of the blades is against the wind which results in lower power output. This can be corrected partially by the use of a blanking arc. All these features make VAWT suitable for lower-power applications when compared with the horizontal type of turbines.
Continuous-time multi-model predictive control of variable-speed variable-pitch wind turbines
Published in International Journal of Systems Science, 2018
Magdi Sadek Mahmoud, Mojeed O. Oyedeji
The components of a WECS include wind turbine, generators, storage and grid (for grid-connected systems). The primary component of a WECS is the wind turbine and it is the main subject of research in most studies. Depending on the axis of rotation, wind turbines can be differentiated into two categories: horizontal axis wind turbine (HAWT) and vertical axis wind turbine (VAWT) (see Figure 1). Compared with the VAWT, the HAWT has a higher wind energy conversion efficiency due to its blade design but it requires stronger tower support due to the heavy weight of the nacelle and the cost of installation is higher compared with the VAWT. The operation of the VAWT is independent of the wind direction but has lower wind energy conversion efficiency and it is more susceptible to higher torque fluctuations and mechanical vibrations. It is commonly found in domestic/private installations where the energy demand is not so high.