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Old Apr 9th 2012, 02:58 AM   #1
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Wind generator

I am designing a small wind generator. The design speed is to achieve an output of 1KW in a wind of 10 mph. If I can achieve an efficiency of 40% at this design speed, what diameter do I need for the rotor?

Givens
Output 1KW
Wind 10mph
Efficiency 40%

Unknowns
Rotor Diameter ?

Answer 3.7m

Would like some help getting to this answer. Thanks.
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Old Apr 17th 2012, 12:16 AM   #2
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Since you need an output of 1kW, you need 2.5KW power (1kW/.4) from the wind.

lets assume that all the kinetic energy of the wind is used in generating power to the the generator.

so the Power achived from the wind = Kinetic energy of the mass of the wind that passes through the rotor per second

mass of the wind that passes throught the rotor per sec.=p.V

where p= density of the wind
V=volume of the wind that passes through the rotor per sec

V= (pi.(d^2)/4)*v where d=diameter of the rotor and v= velocity of the wind.

So going back through the path you'll get,

power achived from the wind = 1/2(pV)v^2
= (1/2)p(pi(d^2)/4)v.v^2
=(1/8)pi.p.d^2.v^3

this can be equated to 2.5kW now find d
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Old Apr 19th 2012, 04:10 AM   #3
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Thank you very much that 100% helped I fully understand now.
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Old Apr 19th 2012, 07:40 AM   #4
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It's my pleasure
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Old Apr 28th 2012, 06:21 AM   #5
Pmb
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Originally Posted by BAdhi View Post
Since you need an output of 1kW, you need 2.5KW power (1kW/.4) from the wind.

lets assume that all the kinetic energy of the wind is used in generating power to the the generator.

so the Power achived from the wind = Kinetic energy of the mass of the wind that passes through the rotor per second

mass of the wind that passes throught the rotor per sec.=p.V

where p= density of the wind
V=volume of the wind that passes through the rotor per sec

V= (pi.(d^2)/4)*v where d=diameter of the rotor and v= velocity of the wind.

So going back through the path you'll get,

power achived from the wind = 1/2(pV)v^2
= (1/2)p(pi(d^2)/4)v.v^2
=(1/8)pi.p.d^2.v^3

this can be equated to 2.5kW now find d
Where do show the number of blades in this wind generator?
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