Wind turbine blades construction

Typical large wind turbine blades consist of outer skins supported by a main spar and stiffeners.The blades are generally constructed using synthetic fibre/polymeric matrix composites, and may have a sandwich construction. 

The properties of the fibres, the matrices and the fibre arrangement within the composite and the fibre volume fraction govern the final strength and stiffness value properties of the composites. These parameters have been illustrated in Hollaway and Teng (2008) and Smith and Yeomans (2002). The matrices for the composites that could be used in the manufacture of wind turbine blades would be polyester, vinylester or epoxies. Glass, Kevlar or carbon fibres can be used with any of the polymers mentioned, but as the rotor blades become larger a hybrid construction of glass and carbon is used. The hybrid concept is often a compromise between the improved... 

Carbon fiber- and glass fiber-reinforced polyamides 6 have been used in the construction of wind turbine blades [15] using thermoset composite technology. It is claimed that such structures are stronger than thermostats for the same weight, and... 

Applications automotive, boats, buttons, chairs, coatings, construction, ducts, electrical components, gel coats, marine laminates, pipes, sheet molding compounds, shower stalls, synthetic marble, tanks, wind turbine blades ... 

Columbia Forest Products applied the principle that imparts adhesive ability to the blue mussel, to design a soy-based formaldehyde-free technology in the construction of hardwood and plywood products. The WhalePower Company designed wind turbine blades using the Tubercle Technology to help them be quieter, more reliable when winds fail, and perform better in turbulent winds (WhalePower 2013). The technology is based on the idea that humpback whales are agile in spite of their size because of bumps on their fins. 

The vane anemometer is an old invention. It can be likened to a small wind turbine with 4-10 rotating blades and a handle, as in Fig. 12.20. Earlier constructions were fully mechanical, where the spindle rotation was transmitted to a pointer through a series of gears. In modern vane anemometers, an electrical sensor records the spindle rotation and the signal is processed, giving the velocity on a digital display. Such an instrument usually is able to integrate the mean velocity over a time interval. 

The resistance of fibre-enhanced polymers to salts and acids has, however, kept them in active use in technical buildings. Silos and large halls are quite often raised using these materials. In the meantime, the industry has been able to gather a great deal of knowledge and experience through the construction of turbine blades for wind farms and the establishment of this technique in boat and yacht construction, as well as in the automobile, aeronautics and aerospace industries. 

Complete sub-stmctures, such as the root attachment construction inserted into the lay-up of a wind turbine rotor blade... 

A typical blade of large wind turbines consists of outer skins supported by a main spar and stiffeners. The blades are generally constructed using fibre/ polymeric matrix composites and may have a sandwich construction with low density polymer foam or balsa wood cores. The epoxy-based eomposites are of greatest interest to wind turbine manufacturers beeause they dehver a combination of environmental, production and cost advantages over other resin systems. Epoxies also improve wind turbine composite blade manufacture by allowing a shorter cure cycle, increased durability and improved surface finish. The utilisation of epoxy infusion or prepreg manufacture (see Sections... 

The vertical spindle, three blade machine [Fig. 12.11 and curve (E) in Fig. 12.10] is a high-speed wind turbine having blades in the shape of airfoil sections like an aircraft propeller. However, instead of having vertical blades, they are bowed to form a catenary thus eliminating the bending moments that straight vertical blades would experience. The peak efficiency of the three blade machines is about 42% at a speed ratio of about six. This means that great care of construction is required for these machines, as in the case of conventional two blade horizontal-axis propellers. A 14 ft diameter machine, tested in a wind tunnel, had an output of 0.65 hp at 130 rpm with a wind speed of 18.2 fps. 

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