1 Historical Development of Wind Turbines Svein Kjetil Haugset, 2007.
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Transcript of 1 Historical Development of Wind Turbines Svein Kjetil Haugset, 2007.
1
Historical Development
of Wind Turbines
Svein Kjetil Haugset, 2007
2
First use of wind - sails
• In use for 6000 years• ”Catching” the wind in a sail• Generating a drag force, D
– due to pressure differences– parallel to the wind
• Drag force, D, on the sail:
v1 usail
v3
phigh plow
2
1
1w
2w v u , relative speed
, area of the sail
, drag force coefficient, unity
D
D
D a c
a
c
3
“Sailing” the mills in Mesopotamia
• First historic record from 1700BC in Mesopotamia.
• Afghan records 700AD show the title: “Millwright” as a common one.
• Mill-ruins in Iran and Afghanistan shows widespread use
• Known as “Persian wind mill”:– purely drag devices, using “sails”– fixed direction – slow rotating (slower than the wind)– poor efficiency, less than 10%
4
”Sailing” the mills elsewere
• Chinese drag-type mills– First record in 1219 A.D., possibly much
older– No screen – the sails were adjusting to
the wind direction– Could be used in all direction
• Recent design:– Savounius-type turbines– Cup aneometers
• Said to be the most “re-invented” turbine.....
5
Turbines in medieval Europe
• First record in Europe in 1185, Yorkshire.
• The “Windmill Psalter” from Canterbury, 1270, with picture.
• Horizontal axed – “sails” does not move parallel with the wind, but perpendicular to the wind.
• Lift-force is dominant: – no longer “sails” but “wings”
• Wind speed is no longer the limitation for the rotational speed.
6
Drag-type vs. lift-type turbines
• Drag force: • Lift force:
2
1 , relative speed
, area
, drag force coefficient
1 w2
w v u
D
D
ac
D a c
2 21
2
v u
, lift force coefficient
1 w2
w
L
L
c
L a c
v1 usail w
axis of rotation
D
v1
uwing
axis of rotation
wu L
7
First industrial revolution?
• Alongside watermills, the only source of mechanical power– 3-7 kW out-put, depending on size and wind conditions
• Used for grinding
• Long lasting design:– Great variation in structural design and control mechanisms but the overall
principle stayed the same till the 18th century.
• By the 14th century, it was widely used in whole Europe
8
Fortunes to the Netherlands
• Need for drainage lead to new development
• The new design featured:– a shaft to lead the power to
ground level.– possibility to link several mills
together– gradually improvement in the wing
design.
• Gave the opportunity for new uses
9
Variations in structural design
10
Scientific research
• Design done by craftsmen for 3400 years
• John Smeaton - first wind scientist?– Measuring efficiency, CP = 0,28
– Designed the twisted blade.
• The modern turbine is “ready”:1. Chambered leading edge (airfoil)
2. Blade-beam at 25% of airfoil length
3. Non-linear twist of airfoils
• 200 years of optimizing still to go!
11
Wild West Wind
• Fan type turbines in USA:– Halladay introduced in 1854– Aermotor ca 1870
• Autonomous system– Turned after the wind– Turned out of the wind at high
speeds
• Higher speed and efficiency
• Widely used– From 1854-1970: 6 million– Still in use to day
12
Wind goes electric
• First large scale electric wind turbine in 1888: Charles F. Brush
– Ø 17 m – 12 kW– step-up gearbox (50:1) – 10 / 500 r.p.m.
• First Danish electrical wind turbine in 1891: Poul La Cour
– low solidity (ratio of area)– airfoil shaped blades– higher rotational speed– 25 kW
13
Modern theory is developed
• Research on propellers and airfoils– NACA (later NASA) in USA and Göttinger in Germany– Airfoil and propeller theory was developed– Modern wind turbines: a spin-off from war-industry (?)
• Albert Betz:– Worked on the theoretical limit of wind turbines: the Betz’ limit.
• An ideal turbine, independent of design, will only be able to extract 59,3% of the available kinetic energy in the wind.
– Was important in developing the Blade Element Momentum Methode.• Ludvig Prandt’l:
– Simplified the complex analysis of Betz.– Developed Prandt’l Tip Loss Factor:
• Theoretical model for the loss in lift at the tip of a turbine blade
• The theoretical foundation for the modern turbine was made!
14
Various attempts:
Smith-Putam, 1941, USA:
•1.25 MW, 175 foot
•2 steel blades (16 tons)
•Down-wind type
•Destroyed after less than 1000 hours
Gedser Mill, 1960s, DK:
•200 kW
•3 glass fibres blade
•Up-wind type
•Basis for the Danish concept
Hutter, 1968, D:
•2 glass fibres and plastic blades
•Shedding aerodynamic loads
•4000 hours before project was ended
15
The Danish Concept
• Three bladed • Up-wind• Dimensioned to withstand gusts• AC – generators• Constant rotational speed• Automatic yawing (turning after the wind)• Stall controlled.
• Great commercial success in the 80s– The 55 kW sold over 10.000– Size gradually grew– VESTAS gained a leading position in the marked
16
Growing in the wind
17
What now?
• Potential for improving:– transmission, mechanical gears is the Achilles heal of the turbine
– lighter and stronger materials in the blades
– individually pitched (regulated) blades
– lower sound level
– decrease tip-losses
– making installations and maintenance more efficient
– CUTING COSTS
• Moving the turbines off-shore– floating installations no one can see (and would not protest against)
• Larger turbines– 5 MW is built, 7 MW is discussed.
18
What have we learned?
• Wind turbines is one of the oldest energy sources we know of
• The development of modern type turbines has taken nearly 900 yrs
• Have had great impact on the economy in various periods
• The modern turbine was made 250 yrs ago
• Basic theory only available in less than 90 yrs
• Still lost of things to do.......