Storing Cookies (See : http://ec.europa.eu/ipg/basics/legal/cookies/index_en.htm ) help us to bring you our services at overunity.com . If you use this website and our services you declare yourself okay with using cookies .More Infos here:
https://overunity.com/5553/privacy-policy/
If you do not agree with storing cookies, please LEAVE this website now. From the 25th of May 2018, every existing user has to accept the GDPR agreement at first login. If a user is unwilling to accept the GDPR, he should email us and request to erase his account. Many thanks for your understanding

User Menu

Custom Search

Author Topic: hey guys ! a new type of windmill (french site)  (Read 40541 times)

NssB

  • Newbie
  • *
  • Posts: 40
Re: hey guys ! a new type of windmill (french site)
« Reply #15 on: December 17, 2007, 04:39:46 PM »
The idea seems pretty "genial", however something is playing in my mind. Is it just me, or is this system going to be terribly unbalanced?

What I mean is, you have wind coming in from lets say NORTH blowing SOUTH. Now lets just picture for one minute that the LEFT side of the rotor is on the WEST and the right on the EAST. So, we have NORTH winds blowing SOUTH pushing on the WEST blades for an ANTI-CLOCKWISE rotation, as depicted in the flash videos. These WESTerly blades are being pushed on from 0 degrees through to perpendicular(so many degrees above WEST). And on the EASTerly plane, you have a feathered situation in order to reduce drag.

Now please correct me if I am wrong, but wont the pressure exerted on one side unbalance the system causing great stress on the mount?


NssB

titof

  • Newbie
  • *
  • Posts: 34
Re: hey guys ! a new type of windmill (french site)
« Reply #16 on: December 17, 2007, 05:36:34 PM »
Well
I think  the entiere device is wind-facing by a little blade in front or behind it like a weathercock...
you see only a model on video
I 've meet this guy and talked with him about it ... :)
don't forget each blade make a half turn in time the rotor makes one turn.
you must have blade's shape which have  the same wing profile "or section".
- I told him : did you try wing-plane profile ?...-
A plate blade works as well !
It 's surely perfectible ... but it's working when all windmills are not !
very efficient.
we can build it .... and big torque !
It's in a corner of my head now.



robbie47

  • Full Member
  • ***
  • Posts: 193
Re: hey guys ! a new type of windmill (french site)
« Reply #17 on: December 17, 2007, 08:19:27 PM »

- I told him : did you try wing-plane profile ?...-
A plate blade works as well !
It 's surely perfectible ... but it's working when all windmills are not !
very efficient.

Hi titof,
How did you get in touch with this French guy? By e-mail? I'd like to have a chat with him.
Surely with flat blades its working as well, I don't argue that.
But, since he compared the claimed principle with a sailing boat in his presentation, I thought his detail over and was actually supprised that he did not claimed this additional principle as well, since it is very obvious (to me).

My French is not so good, so I wonder whether he claimed the basic idea himself. It shows very much resemblance with the patent of Roger Green, alias minsapint earlier.

Anyway, I think its a funny idea, I'd like to have it a go myself and try this out.
The blade angle can be very simple adjusted by a simple timing belt and two different size pulleys (2:1 diameter) between the main axis and the centre axis of each blade
Balancing could be an issue, like NssB mentioned.

titof

  • Newbie
  • *
  • Posts: 34
Re: hey guys ! a new type of windmill (french site)
« Reply #18 on: December 17, 2007, 08:34:48 PM »
I think you guess the mechanics ! ;D
simple!

I saw him on a" innovia" meeting 2 month ago
I talk with him 20 minutes .
you can contact him thew email address on his website

I don't know more
I hope for you he speaks english !
He 's actually shearching for investissors to developpe the project  :)

hard to find...

regards !.. ;D

positron

  • Newbie
  • *
  • Posts: 2
Re: hey guys ! a new type of windmill (french site)
« Reply #19 on: December 17, 2007, 09:45:10 PM »
Hello all!

A bit mixed feelings about finding "my" idea out and about. Oh well, I bet there are many of us. Anyway, I am already in the process (rather slowly thow) of building a windmill looking and working just like this one. The wings are 2000mm high and 600mm wide. They are made of wood, with 10mm steel shafts attached to the middle of the short ends. For the mechanics i have standard chainwheels and chain for mopeds. I have 4 pcs 38T (teeth), one on each wing shaft, connected togheter with one chain, all around them for synchronization of the wings and establishing their relative positions. They need to bee 0, 45, 90, and 135 degrees to each other, or 1/8 of a rev., like this:

  /
I O -
  \

For the rpm reduktion and reference to wind direction I have one stationary chainwheel (16T) in the center connected with a drive chain to one 32T chainwheel on one of the wing shafts. The 16T is to be welded on a 20mm diam. vertical rod wich is fixed to the ground. The 16T needs to be a bit above ground, because there will be another, bigger wheel below it, wich is not fixed to that rod though.
Picture a tube, fitted with roller bearings, on the rod, resting at the fixed 16T. The tube is carrying the whole Wheel.
The arrangement with the chain wheels and chain doesn't transfer any power, if everything is symmetrical
and balanced. The main forces are from the wing shafts pushing on the "cross" type frame.
Output to a generator is to be with a 350 mm diam. wheel, same profile as a standard car alternator. I hope to get more peak power than from an average car generator, though. If anybody is intrested i'll make a drawing of how to make  the chains and belt for the generator to coexist without collision. It's not that difficult,though:
The 38T sync-wheels are mounted on the wing shafts immidiately below the "lower cross" frame. Below
one of the 38T is the 32T mounted, wich is at level with the fixed 16T. The big "belt wheel" has a large enough center hole, it's bigger than the 16T wheel. The belt wheel is fastened to the "lower cross" by means of four
rods fastened vertically to the belt wheel almost at the periferial. Remember, as the Wheel rotates, so does
the 16T-32T chain, so there is no conflict with the belt wheel.
The 38T are for Suzuki, don't know model
The 16T is for Honda MT50/MB50
The 32T is for Suzuki K50
They are all 1/2" x 1/4", japanese standard. Note that there needs to be the absolute relation 1-2 for the rpm
reduction. The other four could be any number of teeth, as long as they are identical.

Finally, to make it possible to adjust for wind direction, the rod with the 16T should be rotatable and have a long handle extending the diameter of the wheel. It's for adjusting for wind direction. I saved that one not to complicate things.

For the big wheels to fit on a 10 mm shaft, i have welded BIG washers meant for use with threaded rods in
building constructions onto them.

I hope to be up and running within a few weeks.
Oh, and the upper cross is simply connected to the lower cross, using the long tube or any other arrangement.
 Problems  I expect: I don't realy like the wings I have. I would have preferred a plastic thing with an aluminum
tube as a shaft. I have weak points where the 10mm shafts are mounted to the wooden boards. And plastics
would be better with moisture. Also it's gonna need some stabilizing. I have no solution for "storm-proofing"
other then building it sturdy enough. 

As time goes by...


titof

  • Newbie
  • *
  • Posts: 34
Re: hey guys ! a new type of windmill (french site)
« Reply #20 on: December 17, 2007, 09:52:43 PM »
Does the wind blow over your house ? ;D ;D ;D
here's one who is not going to pay for electrons ! ;D

Have courage  !
Post your photo when finished ! 8)

Evil Roy Slade

  • Full Member
  • ***
  • Posts: 117
Re: hey guys ! a new type of windmill (french site)
« Reply #21 on: December 18, 2007, 12:08:55 AM »
All good ideas here people.

As has been pointed out, in order to use the wind energy on the 'UP' leg the blade must be
correctly positioned and oriented, which requires the 'blade flip'.

We have experimented with this and found the mechanical losses in controlling the blade outweigh
the additional power generated resulting in a degradation of overall power output. But if you guys come up with something clever I would love to hear about it.

At the moment we are investigating the possibility of CHANGING the shape of the blade instead of flipping it. There are a few ways to do this, all are in the melting pot. I am mentioning this here to sew a few seeds in the fertile brains out there!

ERS

robbie47

  • Full Member
  • ***
  • Posts: 193
Re: hey guys ! a new type of windmill (french site)
« Reply #22 on: December 18, 2007, 09:44:22 AM »
As has been pointed out, in order to use the wind energy on the 'UP' leg the blade must be
correctly positioned and oriented, which requires the 'blade flip'.

I assume you refer to my remark on the flipping of blade shape if shaped blades are used to gain the 'sailing' effect, so let me respond.

The simple solution I have in mind here is not using wood or steel but real sail material. This keeps the weight low and no additional control is needed.
Using sail kind of cloth has of course also some drawback. It's less robust on the long term, and it could make some additional noise ('flapping' of the sail for blades that are in the 'flipping over zone', so between say the 4 and 2 o'clock area)
« Last Edit: December 18, 2007, 11:21:09 AM by robbie47 »

minesapint

  • Newbie
  • *
  • Posts: 12
Re: hey guys ! a new type of windmill (french site)
« Reply #23 on: December 18, 2007, 10:34:25 AM »
My latest design is a pure lift based design.
3 Symetrical foils each at 120 degrees.
A dc worm geared DC motor driven with PMW which averages at the overall sweep speed but speeds up or slows down in the cycle to provide a constant 20 degree angle of incident (optimum for my foil design) to the wind direction. This produces a thrust perpendicular to the wind.The thrust is one way for half the cycle and the other for the other half. I have some diags to explain this....
I have designed the electronics, sourced the motors, I have 3 one metre square blades made of strong polystrene  (in my garage). I need to get back out there and start welding it all together at some point but metal work is not really my strong point.
I was planning on putting it on a trailer so I could drive it to different windy locations, my house is quite sheltered. But this makes the metal work even more complex as it'll need to be easily assembled / disassembled.
The simulations I have done show that it will reach the efficiencies of a HAWT but will work at low speeds and high speeds (you simply reduce the attack angle and thus reduce the efficiency, stops the thing tearing itself apart).
Also with this design you can easily make a multipole motor on the base negating the need for a gearbox which keeps it quiet and efficient.
Interested if anyone wants to help out on this project, by trade I am an electronics / software engineer - need someone with good mechanical skills.




robbie47

  • Full Member
  • ***
  • Posts: 193
Re: hey guys ! a new type of windmill (french site)
« Reply #24 on: December 18, 2007, 11:27:31 AM »
Sorry, wrong action again. One can not delete mistaken posts here.

Earl

  • TPU-Elite
  • Sr. Member
  • *******
  • Posts: 435
hey guys ! a new type of windmill (french site)
« Reply #25 on: December 18, 2007, 12:00:43 PM »
Hi,

All airfoils whether flat or curved have a characteristic called L/D or Lift / Drag.
The L/D ratio and how it varies with the attack angle is the most important thing.
Stalling performance is another.

A flat plate has very bad L/D and should never be used.  Sorry.  You can not
argue against 100 years of aerodynamic research.

The air foil must not be flat.

There have been lots of boats built with vertical wing sails; google Walker wingsail or drivesail, for example.  The Walker WingSail had a movable front part to change the shape of the airfoil from symmetrical, to unsymmetrical on either side.  This achieved a very high L/D over wide range of attack angles without stalling.  It was beautiful and worked well, but had higher weight.  There are other designs, you will find lots of interesting info on people's search for the ultimate sail.

As in all branches of engineering, there are always compromises necessary.  That's life.  Good engineering is to find the best compromises for a certain goal.

Earl
A plate blade works as well !
Hi titof,
Surely with flat blades its working as well, I don't argue that.

Earl

  • TPU-Elite
  • Sr. Member
  • *******
  • Posts: 435
hey guys ! a new type of windmill (french site)
« Reply #26 on: December 18, 2007, 12:04:17 PM »
My latest design is a pure lift based design.
Impossible to have a pure lift design.  There is always drag.
See my above post.

See also http://en.wikipedia.org/wiki/Airfoil
and
http://www.aerospaceweb.org/question/airfoils/q0035.shtml

Earl

minesapint

  • Newbie
  • *
  • Posts: 12
Re: hey guys ! a new type of windmill (french site)
« Reply #27 on: December 18, 2007, 12:22:54 PM »
The foils are not flat.
A flat foil was in fact used by the wright bros with an angle of attack to produce life but flat foils are inefficient.
I use a symetrical foil with a angle of attack of about 20 degrees - if you go above this you stall, less than this reduces lift.
You are right every foil has a drag / lift coefficient. The best foils are non symetrical - interesting effects when the pilot tries to fly his plane upside down!!!!
You have to keep the drag low and the lift high for a chosen angle of attack.
A drag based machine will only go as fast as the wind whereas a lift based one can exceed wind speed that is why sailing boats can zip along.
Like I said I have done a number of sims - there are some quite good foil design apps on the net that you can use to get the design right.
The real clever bit in the software - how to control all the variables (such as blade rotation at any given point in the sweep and the angle of attack) for a given wind speed and rotor loading You have to stop the thing from stalling whilst keeping maximum torque.
.

Earl

  • TPU-Elite
  • Sr. Member
  • *******
  • Posts: 435
Re: hey guys ! a new type of windmill (french site)
« Reply #28 on: December 18, 2007, 01:27:30 PM »
I agree with everything you say, except about the Wright brothers.  They used airfoil wings on their plane, in fact they built a wind tunnel and studied their designs.  Maybe the first wind tunnel ever built?  These two bicycle builders were not dumb.

Earl
The foils are not flat.
A flat foil was in fact used by the wright bros with an angle of attack to produce life but flat foils are inefficient.
[snip]

minesapint

  • Newbie
  • *
  • Posts: 12
Re: hey guys ! a new type of windmill (french site)
« Reply #29 on: December 18, 2007, 01:41:51 PM »
Wright brothers - I stand corrected.
I am sure I read it somewhere....