T Nation

Would This Help Windmill Efficiency?

As my brain is always turning, I have been interested in making a home windmill for power generation for a long time now. Now I was thinking of ways to make them more useful, would this reduce the friction of the system and boost the electrical generation conversion?

I mean it is essentially a zero friction bearing and if I could make it with solid state earth magnets, theoretically, it would last forever with no wear or tear. This would make the life expectancy MUCH MUCH greater for my windmill.

I also have to assume that this will lower the windspeed needed to turn a particular design, as the only resistance would be from the electrical generator. I think I’m going to order me some magnets up and get to work on this.

Please discuss, and Bill, If you read this I would like your input, I remember you had a fair amount to say in my last thread about making my own windmill.

Thanks,

V

A needle bearing design should give very low friction, probably taking away perhaps 1% of the power that could be generated with zero friction. Or I don’t know, maybe 2%. But not anything leaving great room for improvement.

A ceramic bearing would be lower in friction, typically. But they are more expensive. (I had ceramic wheel bearings on my ZX-12R. I think they cost me $200 for the pair, or something like that. Been a while.)

Not that the magnetic bearing (which I have no experience with) couldn’t be perfectly fine. I had thought the value was principally in allowing extremely high speeds, which wouldn’t be needed here.

I suspect they are not easy to home-build.

[quote]Bill Roberts wrote:
A needle bearing design should give very low friction, probably taking away perhaps 1% of the power that could be generated with zero friction. Or I don’t know, maybe 2%. But not anything leaving great room for improvement.

A ceramic bearing would be lower in friction, typically. But they are more expensive. (I had ceramic wheel bearings on my ZX-12R. I think they cost me $200 for the pair, or something like that. Been a while.)

Not that the magnetic bearing (which I have no experience with) couldn’t be perfectly fine. I had thought the value was principally in allowing extremely high speeds, which wouldn’t be needed here.

I suspect they are not easy to home-build.[/quote]

Well supposedly there is a lot of problems when you scale up a magnetic bearing. In fact I think most computer fans use them, or at least thats what I read. So on a small scale I think they are easy enough to build. But if you have a lot of mass, it seem like the magnetic field is not strong enough to keep the device in a stable position, or orbit. I am pretty crafty, and the magnets I would need for a small scale device won’t cost much.

To make the device harvest a lot of energy without having a massive fan I have thought of another idea. A wind funnel, basically a large half cone shaped device which will compress the incoming wind from a large area and force it through a smaller hole. This hole will house a small rotoe and blade system to gather the energy from the wind coming through. In this sense, I should be able to make a larger stationary device which collects the same amount of wind energy as a much larger blade system. It may also make use of slower wind speeds because even at lower wind speeds, they will be moving fatser as they are compressed to the smaller opening.

Do you see any flaws in this thinking? Will the air not compress to any degree and just spill over the sides of the funnel?

V

Vegita, not to derail the conversation but can you provide a link to the “old” discussion? Thanks bub.

http://tnation.tmuscle.com/free_online_forum/music_movies_girls_life/windmill_design

Here is the old thread. Basically, I am going to design the first picture with a mag lev bearing and a funnel that will funnel the air to right around the blades.

V

I know that there is only so much air you can get into a tube, depending on the diameter of the tube.

However, there is a solution to this, but I do not see how that would help you, namely to make the air circulate inside of the tube.

You´ll need some sort of rechargeable battery though, wont you?

Can you even charge them with an inconsistent power output like a windmill?

One of the things you may have to worry about is the prop speed. The less friction in the system the faster it will spin which could cause catastrophic failures at higher speeds. If the prop fins aren’t equal in shape, weight, and balance they could either break or cause uneven wearing. Depending on wind speeds at your location this probably won’t be a problem but it is something to keep in mind. You could always try to get super fancy and build a self-engaging emergency braking system. I’d probably just keep track of the weather channel and if it looks bad engage some brakes or take it down.

Below are a couple of decent alternate power websites which should have links to articles and other sites scattered throughout the forums.

http://www.solarpowerforum.net/forumVB/

http://otherpower.com/

You could just use a sail to funnel as much air to a particular place. I think if you google sail windmill you should get some hits. Seems more simplified than a funnel. Good luck.

never mind. I looked it up, try the wind dam project. Set it up so it can rotate. And it would not look like and it would not look like a giant air raid siren.

You certainly could achieve some increase in wind speed with some arrangement or other: I would suppose the funnel would work though I have no experience with that.

I can attest that when you are under the wing of a DC-3 on the ramp, wind gusts are considerably accelerated. (Which once provided the amusing enlightenment of revealing that a fellow mechanic, who was very hairy guy overall, only in his very early 30s, and always wore a baseball cap, was quite bald for almost all of the until-then-hidden cranial area.)

Basically, a flat board at an angle to the ground, some height above the ground, would be the equivalent. A pic of a DC-3 on the ground would give an idea of angle and height, relative to chord (width) of the wing or board.

But the funnel might work as well. Probably would as a guess.

However, it would not work as well as having blades extending that same diameter.

[quote]Bill Roberts wrote:
You certainly could achieve some increase in wind speed with some arrangement or other: I would suppose the funnel would work though I have no experience with that.

I can attest that when you are under the wing of a DC-3 on the ramp, wind gusts are considerably accelerated. (Which once provided the amusing enlightenment of revealing that a fellow mechanic, who was very hairy guy overall, only in his very early 30s, and always wore a baseball cap, was quite bald for almost all of the until-then-hidden cranial area.)

Basically, a flat board at an angle to the ground, some height above the ground, would be the equivalent. A pic of a DC-3 on the ground would give an idea of angle and height, relative to chord (width) of the wing or board.

But the funnel might work as well. Probably would as a guess.

However, it would not work as well as having blades extending that same diameter.[/quote]

I’m not sure I agree, wouldn’t I be collecting the energy from a higher percentage of the air that moves past my rotor? I mean in a typical 3 blade design, you are only gathering the energy from the wind hitting the blades, which is a small amount. But if it was all funneled to a paddle wheel design windmill with closely spaces blades, nearly all of the wind would be applying force to the blades. You would lose some efficiency due to having no aerodynamic effect, but aerodynamic effect cannot INCREASE the amount of energy a given wind has, only make the turbine more efficient. So being 50% more efficient at collecting 30% of the wind cannot be better than collecting 95% of the wind. And with the Mag Lev Bearing, efficiency should be increased on my design, so maybe the airfoil would only be 25% more efficient, or maybe less. Won’t know untill I get working prototypes.

Orion - I could put spiral fins inside the funnel, but I am not sure it would have a positive effect on the blades. If the air coming out the back of the funnel was spinning, I think even though more air was coming through, it might not be going in a straight line.

Now with a big enough funnel and the spiral fins in it to produce a vortex, you could cut slits in the funnel and actually mount small paddle wheel rotors halfway into the funnel and catch the swirling wind in a predicatable manner. You could have several of them sunk into one funnel. Than might be another idea worth checking into. You could get 3 or 4 cracks at a given strech of wind.

V