Started to build a VAWT

[ffoegw]

I have started a few threads regarding my intention to build a vawt and decided to record any progress here.

As soon as I can recharge my camera batteries I hope to post some photo's.

Several users have recommended that I start small so have taken the good advice. My goal is to eventually built a VAWT with 4x8 rigid sails mounted on a truck axle.

Start small and compromising my intention I have started shopping for stuff.

Here is what I have purchased and scrounged so far.

1/Assorted ABS pipe 4" to 1" diameter.

Hope to use this for the hub/axle/mast. A place to hang the spokes on from which the rigid sails will be suspended.

2/ 12" x 12" vinyl floor tile. ( a lot smaller than 4ft x 8ft panels)

These will be my ridid sails.

3/ 3/4 and 1/2" PVC pipe.

Used for the spokes and suspending the vinyl tiles.

4. / assorted pvc and abs connetors.
   
5. / ABS end cap to mount the bearing.
   
6. / Large caster wheel.
   
   

Cheap way to get some bearings. Will remove the wheel and replace it with a wood 2x4 for the tower.

Promise some pictures when I get going.

Regards

Geoff

[Bruce S]

Geoff

   Another good scrounge would be to go around the computer repair centers and pick up old hard-drive. The Neos in them are very powerful and will be free , just a little hammering to get them out:-))

Also another source of bearing, would be inline skates. These will not last very long in the elements, but are very good high quality bearings.

Are you planning on building your own genny or a conversion?

Cheers!

Bruce S

 

[vawtman]

Geoff,How do you plan on cupping floor tiles? if you leave them straight it will act like a weathervane.Glad to see you getting started.Cant wait til you get the camera charged so we can help more.Is this a 2bladed hbar configuration?

[ffoegw]

Bruce,

I am not planning to hook a genny to this one.

Just going to test out the vawt idea's in my head first before I progress to actually making power.

I'm thinking there will be lots of torq and not so much rpm's so will probably do some kind of mechanical / hydraulic PTO where I can set the rpms to exactly match an off the shelf genny and go for 117/60 right off the mill.

Thanks for the inline skates bearing idea. I know a good source  for those.

I live in Georgetown, Ontario where there is a recycling center where people dump everything they don't want and others can scoop it up for cheap.

Saw some electric baseboard heaters which could quickly be put to good use once I start generating some power.

Geoff

[ffoegw]

vawtman,

Glad your keeping an eye on me.

I am going to leave them straight.

Hinge one side.

elastic/bungee the other.

The largest problem I think I will need to overcome are the centrifugal forces on the rigid sail.

I have a couple ideas to balance the sail and compensate for the centrifuge however, am also thinking that the centrifugal forces could be put to use as a brake.

Geoff

[ffoegw]

Oooops there was more,

Yes, 2 bladed will keep it simpler and cheaper for now but 4 blade or more are possibilities.

If this works I am thinking it could be built in a modular way where more spokes / blades could be either stacked upwards or extended outwards.

This should make it easier to grow or service the mill.

The hinge mentioned above will be a 360 hinge however, am thinking I would like to include a simple attachment which could be adjusted to limit the rigid sails travel to different angles.

hmmmmmmmmmmmmmmm   it's windy today.

Geoff

[Bruce S]

Geoff;

   On the extending outward, the one thing to keep in mind is that once you get past a meter in length the PVC starts to really get bend happy. One thing that could keep the flex and weight down would be the expando-foam, just check the type.There's a closed cell type that is much better than the type for insulating inside door frames.

Stacking upwards is good, kind of like what Norm has done with plastic cups on a micro-mill, just offset each one by degrees equal to the total number of sections divided into 360.

And of course, once you get ready to put something up the wind will go hide:-))

Cheers!

Bruce S

[vawtman]

Hi Geoff,I once tried using magnets with similar poles facing each other to open and close the blades during rotation the problem was getting it started.The idea I thought was sound because the upwind blade would compress and the downwind blade would open and grab wind.Once I started tinkering with airfoils there was no going back.No starting problems that was a major hurdle jumped.Now that its finally warming up im going to put the conversion on it and see how to load it for different wind speeds its not going to be easy.Im planning on a variable resistive load for heating only.I think and am hoping the 5hp will control the 8x8 in higher winds.Build your idea and test it.The fun part is if it doesnt work it makes you want to win and then you get into the advanced stages of our lovely virrus.My wife works at a pharmacy and they have nothing to spike my coffee with yet.Ive been told to marry the darn thing a few times.Cool

[thefinis]

Here is a good way to test the power it is making without a genny but you will need a way to check the rpms. For a vertical shaft a spring scale should work to read lbs of pull.

How the Prony Brake Measures Horsepower

The problem of how to measure the horsepower of a rotating shaft was solved by Gaspard de Prony in France in 1826, when he invented the first friction brake. This device came to be known as the Prony brake. The following sketch, (below) shows the simplicity of Gaspard de Prony's invention. In use, the stationary lever (D) is clamped around a rotating shaft (A) and the two bolts above the shaft are tightened until the engine is working up to full load. Weights (B) are then added to the scale pan until the lever (D) drops slightly away from the upper stop (C). To calculate horsepower the only things needed to be known are the length of the lever (D), the weight of the lever (D) at its right hand end, the additional amount of weight (B) added to the scale pan and the speed of the shaft (A) in rpm.

  The calculation is:

Foot Pounds per Minute = Pi x 2 x Length of D x RPM x Weight

And because Watt's figure of 33,000 foot-pounds per minute per horsepower has survived through both the 19th and 20th centuries, we end up with:

Horsepower = (Pi x 2 x Length of D x RPM x Weight) divided by 33,000

When you get to the stage of adding the pto/hydraulic drop me a line if you need help. Good luck and expect problems experimenting but don't let them discourage you.

Finis

[ffoegw]

Thanks to everyone for all the input.

vawtman,

If a sail is mounted perpendicular to a spoke with a frame and the leading side of the sail is attached to the frame with a hinge.

Much like a sail boat the trailing side is also attached to the other side of the frame but this time with an elastic material.

Except when the wind is blowing exactly from the leading to trailing edge there should always be some rotational pull on the spoke.

The other 359.99999999 degrees should alway provide some rotational power.

While one sail is in that moment of time that it cannot get power from the wind the sail on the spoke 180 degrees away should be obtaining the maximum amount of power from the sail.

Try to imagine the sail in any position other than that exact point where the wind is from the leading to trailing edge.

The wind should ALWAYS extend the elastic away from the spoke where the frame is attached to the the trailing edge of the sail.

If that elastic is extended then rotational power is also always being applied to the vawt.

I have tried to upload some photo's but don't see them.

Maybe they went somnewhere else?

I'll try again later.

The vawt is built and ready to deploy however, ......... no wind today.

Regards

Geoff Wright

[ffoegw]

Bruces,

Ive noticed the bend happy qualities of pvc already.

Thanks for the foam idea!

I also was thinking that I could build spokes with two peices of pvc cemented together like a ladder.

Geoff

[ffoegw]

finis,

I didn't know about the prony brake thing.

Thanks.

I am wondering how I could practically apply it to a vawt.

RPM's?

I have one of those cerial box step counters that joggers like to use to measure how many steps they have taken.

If I can mount it underneath the vawt and have a flapper with a spring mounted to one of the spokes which hits it on every rotation I should be able to take a measurement every hour and calculate average rpms.

Any other idea's for a tachometer?

Geoff

[ffoegw]

Thanks finis,

Here is a link to a post where I try to explain where I eventually plan to go with the hydraulics idea.

Please read it and keep me honest.

I have a lot of hydraulics questions which are still unanswered. Thanks for your offer to help.

http://www.fieldlines.com/comments/2006/3/10/162433/857/15#15

Geoff

[ffoegw]

Posted photo's in another diary entry.

http://www.fieldlines.com/story/2006/3/12/19217/2657

[ffoegw]

Here is the link to the first mini vawt deployment.

http://www.fieldlines.com/story/2006/3/14/133853/229

Just providing some better continuity to the diary.

[ffoegw]

Started to build a second vawt.

It should have the following changes which I hope will greatly improve design and performance.

1. / Using 1 1/2" abs instead of 3/4" pvc for the spokes. The 3/4 pvc was too "bend happy".
   
2. / Gravity seems to make the sail frame want to hang down or bend so will try to mount the sail under the spokes so that instead of fighting gravity it is complying with it. (It can't droop any lower than underneath).
   
3. / Put the hinge a little off center instead of at the end of the sail or mount a sail behind and in front of the hinge. This should help balance the sail(s) and stop centrifugal forces determining the angle of attack instead of the wind and the spoke.
   
4. / Balance the sail with weights if necessary before mounting it on the hinge. For the same reason identified above.
   
5. / Design and make a sail which will be pulled into a typical airfoil shape so that instead of just drag the vawt will exploit aerodynamic advantages.
   
6. / Design and build the vawt so that it can easily be extended upwards or outwards just like adding extra sails on a sail boat.
   
7. / A more solid and adjustable method to attach elastic or bungee for the mainsheet.
   
   

Already getting excited about what the outcome may bring.

Any other suggestions?

Geoff

[ffoegw]

Here is a photo of Ffoeg2 the second version of a vawt with the principles that give motion to sailboats applied to a vawt.

There has been no wind for a couple of days here so no use taking any video.

All the improvements I listed in the post above have been fully implemented except #3 and 4, however I have left room to extend the boom the sail / hinge is mounted on so I can finish #3 and #4 later.

Regards

Geoff

[ffoegw]

35kph winds forecast on Saturday.

I'll take some video then.

Getting excited.

http://www.theweathernetwork.com/weather/cities/can/Pages/CAON0258.htm#longTerm

[ffoegw]

We really didn't get much wind so I decided to rebuild the sails again.

This time I made rigid airfoil shaped sails / blades after reading some of your comments and also reading up on aerodynamics.

Also #3 and #4 has been implemented however, I am back to a non gravity sail on top of spoke configuration just to see what happens.

The Ffoeg VAWT now looks like something out of Star Wars.

Supposed to be a thunderstorm this evening. with some wind?

Here is the latest photo and hope for some video later:

Regards

Geoff

[vawtman]

Geoff

  Im guessing but I think your having trouble with low wind startup.You mentioned in a earlier post that has the blades sped up the centrifical force would throw the blades out.If thats happening I cant see you getting more than 1tsr and the airfoil wouldnt help much unless the blades where fixed.

  Thats a cute little airfoil you made and is there a way you can curve it to the rotation and test?

  I also think youll eventually have to connect the rotor to the center of the blades if your going bigger.Or top and bottom.

  Keep plugin along your doin good.

[ffoegw]

vawtman,

Don't understand what you mean by this:

"is there a way you can curve it to the rotation and test"

Sounds interesting though.

The vawt above broke before I could take some video. The bolt which holds the caster bearings to the 2x4 came loose and it started to wobble and snapped a 1/2 ' pvc connector. Because it was connected to the spoke I had to cut of the end, splice and rebuild everything up to the sail/blade.

Any other idea's for giving me a more stable mount for the hub which I can still move around?

The vawt is presently mounted on a fence post less than 10ft from the bottom of a 3 storey building. I would like to take it out to some nearby open fields and strap it to a fence post, thats why the need for portability.

I have since fixed the vawt and tightened the bolt on the bearings.

Now have some video which I am going to post right after this.

I did move the hinge more towards the center of the sail/blade so that centrifugal force shouldn't have such a large effect. I think however this effect could be something which keeps the vawt within safety limits during very heavy winds.

Also put the sails under the spoke again. Think this gives it more stability having weight below the bearing. Would like to try an over and under the spoke sail arrangement also. Maybe later.

There does not seem to be any problem starting in low winds, in fact I am surprised how little it takes to get some rotation however, I have never put a load on it yet.

This seems to be an imrovement gained by the airfoils.

I think the radius could be increased giving the airfoil a little more time and space to get some wind glued to the sails.

I think the tsr will go a little over 1 without a load however it would become more difficult as the speed and centrifugal forces increase. I think this is a good, safe thing.

The top and bottom connection seems to be a prudent thing to do just for safety and peace of mind reasons. I will keep that in mind when I supersize.

Thanks for keeping your eye on this stuff.

Geoff

[ffoegw]

Here is the latest video, it shows some rapid acceleration when a gust hits it:

It's in the post here:

or you can click on Ffoegfixed.avi in my file link here:

http://www.fieldlines.com/user/ffoegw/files

regards

Geoff

[vawtman]

Hi Geoff

  My comment to curve the airfoil to the rotation of the turbine is just what I said.Instead of having your airfoil straight, curve it to your rotor diameter.

  Ill reply to your other questions in a bit if these pics go through.

[ffoegw]

vawtman,

I think that is a great idea!

Just like on conventional airplanes the underside of the airfoil is cambered to give more lift even when the angle of attack is 0.

It would be like cambering the inside edge on the vawt airfoil which now because of centrifugal forces offsetting the airfoil would continue to provide lift even a the greater rpms.

Think I'll have to try it.

thanks

Geoff

[vawtman]

Geoff

  I struggled with low wind startup and slow speeds in low winds until I thought of this airfoil design.Sometimes it seems to be spinning with no wind.It also seems the taller the blade the more rpms in low winds.

[kays2002]

A wind turbine without the dependence on the weather or wind velocity is a very inventive & ingenious idea.  Harvesting the wind will be farfetched solution to huge towers and large controversial wind forms.  I was just thinking that what will be the result if modify the wind machine by adding some thing from the hydro turbines, I mean the something similar to an impulse turbine but instead of water it must be run on compressed air from a secondary compressor either to be powered by the generated electricity (after initial startup) or by using bio diesel.

[ffoegw]

Vawtman,

That was my next door neighbours suggestion.

To make the blades taller and perhaps less wide.

Geoff