Turbines Power Point - University of Texas at Austin
Turbines Power Point
Teacher Script
Slide 1
Structures are designed to support or carry loads without failure or collapse. Natural and man-made structures are encountered everywhere (see slide two).
Wind turbines are structures – materials, loads, economics, aesthetics, safety, and manufacturability are design issues.
Slide 2
People encounter structures everyday. The slide above compares structures found in nature (natural structures) versus structures made by man (engineered structures).
Natural Structures: caves, tree trunks, tree branches, spider webs, beaver dams, turtle shells, honeycombs, beehives…
Engineered Structures: rooms, columns, beams, trusses, dams, portable homes, cubicles, domes…
Slide 3
In the above slide, a load P is applied to a square beam. The load causes compression on the top of the beam and tension on the bottom of the beam. The yellow line on the beam illustrates the shape the beam will take due to the applied load. The slashed line represents the neutral axis. The neutral axis experiences neither compression nor tension; it represents steady state.
Failure due to compression or tension is shown below the loaded beam picture. In this case, the beam is made of wood. Wood is much stronger in compression than in tension; thus, the beam will first fail in tension.
A wind turbine is affected by wind loads which cause compression and tension. By understanding the basic beam structure, one can more easily understand how wind loads affect the parts of a wind turbine.
For example, the rotors (blades) of a wind turbine can have edge and flap bending moments due to applied loads. An edge bending moment is caused when the rotors move up and down in a vertical direction. A flap bending moment is caused when the rotors move sideways (flapping in the wind) in a horizontal direction. Excessive edge and flap bending moments can cause fatigue (like bending a paper clip), which can cause wear-and-tear and lead to structural failure.
Slide 4
The Tacoma Narrows Suspension Bridge in Washington State collapsed in November 1940 due to wind-induced vibrations. Wind-vibrations also affect wind turbine rotors; thus, it is important to design accordingly.
(Play the movie by clicking the picture)
Slide 5
Windmills and wind turbines come in many shapes. Early Dutch windmills crush grain, farm windmills pump water, and wind turbines create electricity. Wind turbines are either vertical (Darrieus) or horizontal (1-Blade, 2-Blade, and 3-Blade) to the ground. Drag devices such as Savonius also exist. Horizontal (parallel) wind turbines are the most widely used for creating electricity today.
Slide 6
Turbine failure usually occurs due to extreme wind loads (e.g. hurricanes). The extreme wind loads create turbulence which causes fatigue (e.g. bending a paperclip back and forth until it breaks).
Slide 7
Sandia National Laboratories has constructed three Micron 65/13M wind turbines in Bushland, Texas. The three turbines are being monitored by various instruments to determine wind speed, wind direction, and structural response.
Limited data is available at WE-Tex:
MartinRegner/Turbines/Home.htm
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