Author Topic: I know...the community is about HAWT here but...  (Read 4600 times)

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richp0169

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I know...the community is about HAWT here but...
« on: July 15, 2014, 09:11:32 AM »
I am a total newbie, been poking around Other Power for years though, doing a lot of reading, research, planning and this concept of a VAWT intrigues me so much that I am going to develop a scale model (very small scale, likely less than a foot tall total) to test and prove the concept.  (Really wish I had a 3D printer, that would make this much easier...)

www.cal-epower.com has devised a VAWT for industrial use that is over 30% efficient.  Granted, that turbine is very large, 10' diameter and 50' tall blades.  The concept is for there to be a forward facing airfoil.  This will accelerate the wind on the face of one side of the turbine while protecting the reverse side.  The drag is reduced on the "non-flight" side of the wing.  Seems like a very interesting idea to play with to me. 

Here's a mock up of what I plan to construct (materials unknown, likely a combination of wood/plastic/cardboard and filler material (plaster/fiberglass).  I'm building a prototype model so...it's not going to get actual flight time.

The goals are:

1.  Test just the savonius turbine blades alone without any airfoil to get a base measurement performance:  Startup, velocity, torque.

2.  Test the turbine with the airfoil and compare the performance.

3.  Use different blade, wing configurations to maximize performance.

I will post on my findings and update.

Here's a 3-D rendering of the concept.





« Last Edit: July 15, 2014, 09:19:52 AM by richp0169 »

electrondady1

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Re: I know...the community is about HAWT here but...
« Reply #1 on: July 15, 2014, 10:45:00 AM »
i build vertical mills,
i think it's a great idea.
it's been around for a long time .
glad your going to start building.
don't build too small, or it will be difficult to monitor improvements.
there is no way to scale the density of air so a model might react act differently than full size.

Flux

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Re: I know...the community is about HAWT here but...
« Reply #2 on: July 15, 2014, 11:22:00 AM »
My feeling is that it will work ok but at the cost of a far bigger structure, all this lot has to be supported in such a way as to survive the large forces purely due to its area presented to the wind.

One experiment you may like to try is to see whether the gaps between the blades help in this case, it will be working as a panemone, not a savonius and I doubt that it will be any better than with all 3 blades fixed directly to the shaft without the gaps.

To me this is a bit like adding a shroud to a HAWT to make it a ducted turbine, you gain, but at the expense of a large structure. It may not work any better than a larger Savonius with the same wind loading.

Anyway it does look rather attractive, good luck with it.

Flux

richp0169

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Re: I know...the community is about HAWT here but...
« Reply #3 on: July 15, 2014, 12:10:24 PM »
Electron Daddy:

I'm in it for the process and the fun of it.  There's a few other concepts, more traditional (tri-blade, dual blade, etc) I want to try as well.  Do you currently have a system in place with a VAWT?

Flux:

Yes, there is more structure, however with proper material selection, the airfoil can be made durable and light at a much larger scale.


stephendv1

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Re: I know...the community is about HAWT here but...
« Reply #4 on: July 15, 2014, 12:39:07 PM »
Interesting.  It looks like your 3D rendering has a concave surface where the cal-ePower diagrams have a convex surface, was this by design?

richp0169

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Re: I know...the community is about HAWT here but...
« Reply #5 on: July 15, 2014, 12:43:44 PM »
The angle of the rotation on the model makes that appear much more exaggerated.  It truly isn't as concave as it appears.
This is my take on it, so yes.  In my opinion, the airfoil shape is rather symmetrical, just offset, leaving free air behind it and acting as a barrier to the turning turbine. 



« Last Edit: July 15, 2014, 12:47:48 PM by richp0169 »

electrondady1

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Re: I know...the community is about HAWT here but...
« Reply #6 on: July 15, 2014, 05:11:46 PM »
their  animation shows a 4 blade blow through design.
your illustration shows three.
in this case that could be crucial
i can see where a shroud like that will improve power.
but all that extra  material could construct a second  windmill.

i have a few concepts spinning around outside.
 rectified and hooked to some dc fans. i wouldn't say it's a system.
the wind blew all mine apart a few years ago and I'm just getting started again.




 

 


Mary B

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Re: I know...the community is about HAWT here but...
« Reply #7 on: July 15, 2014, 05:22:17 PM »
Don't overlook the lift blade VAWTS either. Route I am going when I free up some cash

Smithson

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Re: I know...the community is about HAWT here but...
« Reply #8 on: July 15, 2014, 07:36:50 PM »
Hi:  Back in the 70's and 80's there was a simple Vertical axle machine that used a tail vane (like this one) ( similar concept) and a cam to change the angle of attack of the vertical blades as they revolved around the axis.  It was called the Pinson Cycloturbine.  In many ways it was a exceptional design.  I never could find a diagram of the cam.  But would like to.
http://wind.nrel.gov/public/library/3046.pdf
Arch

gizmo

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Re: I know...the community is about HAWT here but...
« Reply #9 on: July 15, 2014, 08:35:02 PM »
Your going to need a much bigger tail than the one shown in the 3d graphic. That big airfoil out the front will need a much bigger tail to keep it facing the right direction.

I tend to agree, its a big structure for not so big gains. It would be easier to double the height of the VAWT than try to duct more air into it.

Plus I've never seen the point of a VAWT that needs a tail. The one advantage a stand alone VAWT has over a HAWT is its lack of tail, and the fact it can respond quickly to changes in wind direction. If you need a tail, then may as well build a HAWT and achieve over 30% with known designs.

Glenn

electrondady1

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Re: I know...the community is about HAWT here but...
« Reply #10 on: July 16, 2014, 07:49:35 PM »
 so,with out a 3D printer, a nice vertical can be built with sonotube sliced length wise.



richp0169

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Re: I know...the community is about HAWT here but...
« Reply #11 on: July 17, 2014, 09:28:54 AM »
Gizmo:  The tail is to specifically keep the airfoil in the wind.
Electron Daddy:  Yes, all material ideas are being considered for a prototype.
Mary Alana:  I have another three blade lifting VAWT design that will get attention as another time.

Thanks for the support, ideas and input!


gizmo

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Re: I know...the community is about HAWT here but...
« Reply #12 on: July 22, 2014, 12:31:33 AM »
Gizmo:  The tail is to specifically keep the airfoil in the wind.

I realise that. Look at the size of the tail, and the size of the airfoil, looks like the airfoil is bigger and further out from the axis. Therefore its going to be forced downwind, as its presents more resistance to the wind that the little tail, and the thing will end up facing the wrong way. Like I said, your going to need a much bigger tail than the one shown, or a tail extended much further out than shown.

And if you need a tail, then save time and effort and build a HAWT instead. I've been down the path of building VAWT's with tails, and now I only build HAWT's. Its easier to build a HAWT with better performance than claimed by this tailed VAWT design.

Glenn

richp0169

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Re: I know...the community is about HAWT here but...
« Reply #13 on: July 22, 2014, 12:29:36 PM »
Absolutelyl Gizmo, the performance of a HAWT has always been superior to a VAWT, however I am not in a location that would tolerate one.  I can get a VAWT up without much difficulty...

electrondady1

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Re: I know...the community is about HAWT here but...
« Reply #14 on: July 22, 2014, 06:17:27 PM »
it shouldn't require a tail.
if the point of rotation is in the nose of the air foil  the mill  should pull itself down wind.

richp0169

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Re: I know...the community is about HAWT here but...
« Reply #15 on: August 26, 2014, 03:21:19 PM »
Granted Electrondaddy that the builder gets the thing balanced and the airfoil exactly right, I agree.