Stepper motor as a generator??

[Jonathan]

[QUOTE=wiatroda;23291]Jonathan have a loot at this video, It nicely shows how turbulent wind is in urban area.[/URL]

The thing is it will vary for each site, which in my opinion makes discussing in general terms not very productive.
The VAWT in that video is a drag based machine (so TSR<1), so is inherently inefficient compared to any HAWT, and better VAWTs. At a higher windspeed (which after all is what we're interested in since power is proportional to wind speed [b]cubed[b/]) the turbine with TSR>1 (i.e. VAWT or HAWT with airfoil profile blades) will generate much more power. If the wind is turbulent then I think neither of this type will be that effective since when the wind is coming from many different directions the resultant force on each 'section' of the blade will be different - so the overall torque may not be that much. So that implies that yes a drag based VAWT would work better than HAWT in turbulent wind, but still not generate much power as it wont benefit from higher windspeeds. Also in tubulant winds fatigue on the VAWT blades, which are already highly stressed compared to a HAWT, will be greater possibly leading to faliure.

I tend to agree that VAWT should be better in turbulent wind, just from common sense. I think that it's not worth considering having a wind turbine if your site is very turbulent (unless you don't need much power, say off grid). However if you've made it yourself, and therefore very cheaply then why not experiment... design the generator so you can try VA and HA with the same swept area and compare.

If the wind is that turbulent then you should just put the turbine higher, and use a HAWT. Granted planning permission is an issue, but it's clearly the best way.

Do you think HAWT is able to follow so changing wind direction ?? I doubt it.

Not one of a useful size, the moment of inertia is high and therefore cannot accelerate into the wind without a larger force from a big tail, and the gyroscopic forces would be large, so it is going to need a very strong tower to do that ... etc it's just not worth it.

Also in the video it says 'The HAWT will turn in lighter winds so it it more efficient' ... which is a bit of a dodgy statement.

[wiatroda]

That's what I thought to build, both HA and VA and compare performance ( generator can be the the same to cut costs and make whole experiment more data accurate) .
Permission makes me hesitate to build either one of them but the idea is still in back of my head. My garden location is very turbulent place and that's why I consider VAWT more appropriate for this location. Lots of reports say vawt doesn't need tower to be so high as havt so there is less risk it will fall to neighbours' gardens :). When I have some spare time (or money) I think I'll play a bit with stepper as generator and to control load by PWM proportionally to rotor RPM. Just an another idea.
Anyway, your generator looks superb. When are you going to put it up?

[Jonathan]

Lots of reports say vawt doesn't need tower to be so high as havt so there is less risk it will fall to neighbours' gardens :)

Lots of reports say that wind speed increases with altitude, from which you can conclude that having the turbine near the ground is less effective.

Anyway, your generator looks superb. When are you going to put it up?

Thanks, but there's still things I would improve if I made another one. No idea when as we don't have space for it (according to my Mum and Dad). I'm waiting for an opportunity to appear to mount it...