Wind Turbine Power Generation
2 momentum and impluse related questions?
I need help answering these two questions.
1. At a hydroelectric power plant, water is directed at high speeds against a turbine blades on an axel that turns an electric generator. For maximum power generation should the turbine blades be designed so that the water is brought to a dead stop or so that the water rebounds?
2. During a Chicago wind storm, winds can whip horizontally at speeds of 100km/h. If the air strikes a person at the rate of 40 kg/s per square metre and is brought to rest, estimate the force of the wind on a person. Assumme the person is 1.5m high and 0.5 m wide. Compare to the typical maximum force of friction (mew = 1.0) between the person and the ground if the person has a mass of 70kg.
1. deadstop
2. surface of person is 1.5m x 0.5m = 0.75 m^2
so air strikes person at 40kg/s/m^2 * 0.75m^2 = 30 kg/s
speed of air is 100km/h = 27.8m/s
force of air is 30kg/s * 27.8m/s = 834 kg.m/s^2 = 834N
Maximum force of friction is
mew * m * g = 1.0 * 70kg * 9.8m/s^2 = 686N
Translation: the person is going to slide!
Although from personal experience it takes a lot more than 100km/h to make you slide and at 100km/h the force of the wind is much less than your own weight.
Airborne wind turbines
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MAB-311 Giant wind turbines on breakwater Photo Mugs MAB-311 Giant wind turbines on breakwater Bilbao harbour, Spain Mark Boulton Please note that prints are for personal display purposes only and may not be reproduced in any way. contact details prints ardea tel and 44 (0) 20 8672 2067 …. |
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Computer graphic of wind farm at sunset Photo Mugs Wind turbines. Computer graphic of windturbines against a red sky during sunset. Windpower creates no emissions and is reasonablyefficient. By altering the angle which the turbineblades present to the wind, some adjustment may bemade for changes in wind velocity. However, thenature of the weather means that wind power mayonly be used as an adjunct to other sources, reducing the demand on fossil or… |
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View of wind turbines in South Yorkshire Photo Mugs Wind turbines. View of several wind turbinesused in the generation of electricity. Wind powercreates no emissions and is reasonably efficient.By altering the angle which the turbine bladespresent to the wind, some adjustment may be madefor changes in wind velocity. However, the natureof the weather means that wind power may only beused as an adjunct to other sources, reducing thedemand on fossil o… |