turbine size for 12-15 mph wind ?

[hngni]

hi all

i am looking for ideas on sizes for an ariel flux turbine to work in low winds 12-15 mph producing 48v about 3kw

is this possible or am i expecting too much

thanks in advance

herbie

[fungus]

You'd need a 40' diameter prop - larger than anyone here has ever built..

[sk windpirate]

Keep up the BIG Thoughts. But you might have to lower your standards.

Low winds have no energy. Even a pirates fear them.

[electrondady1]

it may be necessary  to build multiple smaller  windmills in order to achieve your

power requirements.

[scorman]

You haven't defined your operating point clearly enough.

If you mean that the avg WS is 12mph, then the wind capacity is only 4.4KW at 100% for an 18 footer like Dave B has built and that isn't big enough.

I you mean the avg WS is 15mph, then the above 18footer will give you 8.6KW at 100%,

so 3KW delivered is possible.

If you mean that the maximum power you will be designing the generator will be 3KW, then you are in the right ballpark.

Caution: a 10 footer is relatively easy to construct and plant on a tower, however an 18footer similar to what I am currently building has a head asssembly that weighs 200+ pounds and that is no toy to get 50+ feet up into the air. Most here will tell you to get your feet wet with a modest unit, and then scale up once the kinks are out.

The current Jacobs 23 footer delivering 3KW at 15mph (rated at 10KW at 25mph) weighs 2500 pounds!!

http://www.windturbine.net/specs.htm

note: In above calculations I am choosing an arbitrary Weibul distribution factor = 2

semi OT ...does anyone have any documentation how they are doing dynamic pitch control (not furling) as in their advertising??

Stew Corman from sunny Endicott

[windstuffnow]

  Area = Power / ( .00508 x windspeed^3 x efficiency )

  Diameter = sqrt(area / .7854 )

 3000watts / ( .00508 x 15^3 x .3 ) = 583sq ft

 sqrt( 583sqft / .7854 ) = 27.25 ft diameter

I wouldn't use PVC blades for this one.... ;o)

.

[Dave B]

I know this has been posted before but this link and charts have been very helpful for me from a design stand point. http://www.ndsu.nodak.edu/ndsu/klemen/Perfect_Turbine.htm  I'm sure there are some who will argue against some of these figures but to me it's been realistic and a very good indicator of the efficiency of my alternator and blades matching. Dave B.

[Flux]

All depends on what you mean by a 12-15mph wind. If that is the sort of wind speed that you want to see 3kW then you will need a monster.

If you have an average wind speed of 15mph then that is very high and that changes things a great deal.

Wind speed and wind turbine rating is so confusing that few people have any idea of what is realistic.

The rated power of a turbine is a pretty arbitrary figure, it may be the maximum it can produce without burn out, it may be a figure that it produces at a wind speed chosen by the manufacturer or in some cases a dream based on nothing credible. It is never a figure that the machine will push out hour after hour like an engine driven generator. In the worst rated commercial cases you may only see its rating for a few minutes a year ( if ever sometimes)

The typical average power produced by a 3kW rated turbine could be down in the hundreds of watts on a typical site. If you need 3kW continuously then you may be looking at a 15kW machine.

Someone has already mentioned Michael Klemen's site. I suggest you have a good look at that or Paul Gipe's books.

You really need to consider your load requirements in kWh and work from the energy in the wind. Working with peak power figures is not going to give you much idea.

3kW peak rating in a 15 mph average wind area is very practical, but 3kW out at 15mph constant wind speed is a very different thing.

Flux

[hngni]

hi all

thank you all very much fo your detailed replies

i did not explain correctly what i needed

the average wind for here is 12-15mph

so i wanted to build a machine for 48v and put out around 1kw in a 15mph wind

blade size, rotor size, magnet size, and coil winding details are what i need if some one has done this already

thanks again

herbie

[bob golding]

12 to 15 mph average is very high as flux has pointed out already. we need more details of what you intend to do with the power. are you feeding in to batteries? heating coils? gridtie? the "standard" 10 footer our hosts build woud be fine for 1 kw into batteries or grid tie with that sort of wind speed. if you are intending to feed it into a resistive load like heating elements you are going to need some sort of control circuit or it will never get out of stall. you will will need some sort of charge control anyway if you are feeding batteries. gridtie will depend on the inverter you get. resistive load check dave b's diary. good luck.

cheers

bob golding

[hngni]

hi all

i am going to charge batterys (48v) via a controller and use the dump load to heat water

i just want to make the best use of the low speed winds as i do get a lot of wind around 12mph

thanks herbie

[Flux]

You seem to be talking about actual wind speed, not average.

If you copy Dan's 20ft machine then that would come close to your 1kW at about 15mph.

I don't think there is any point in doing other than copy Dan, he has sorted out most of the bugs and you will have head start on anything else. You may well see your 3kW quite often. If you really want to make reasonable use of heat on that set up I would if anything over build the alternator with a few more magnets or bigger ones and add line resistances as water heaters as well as using the dump load. I wouldn't do any modifications unless you are really sure what you are doing as you may open another can of worms but there is a good case for heating water rather than stators if heat is useful to you.

Flux

[hngni]

HI FLUX

thank you for your reply

are there any links to dans 20ft machine as i had a look and can not find it

hrrbie

[ghurd]

Here,

http://www.otherpower.com/20page1.html

[hngni]

hi all

thank you all very much for all your comments and guidance

i will have to do some reading and site viewing now before i start building this monster

i have built a 48v generator and about to start carving 12ft blades for it

when i get it up i will see how it preforms in low winds before istart on the big one

many thanks again for all your help

herbie