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Old 09-29-10, 02:46 PM   #21
Patrick
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It looks to me like there's more convergence than divergence in both of the shrouds. Also, the article states that they're trying to create a low pressure area behind the blades:

"FloDesign wraps its wind-turbine blades with a shroud which operate on the principle that separating the air into two streams (one going through the blades and one going around them) creates a vortex at the tail-end of the turbine when the two streams converge back into one. It is that vortex that then adds extra 'pull' on the turbine blades, causing them to spin more and/or at greater efficiency."

When you think about it that's really what you want. A jet engine has lower pressure in front of the blades. Spinning them pulls air in and compresses it, creating a higher pressure on the back sides of the blades that then goes into the combustion chamber. Now reverse it for your wind turbine. You have high pressure on the front of the blades from the wind's impact and they are curved so that lower pressure on the back will create a turning torque on the turbine.

The outer shroud appears to work like a reverse augmentor tube, creating a low pressure area at the back of the small shroud to increase airflow through it.

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Old 09-29-10, 06:54 PM   #22
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Makes sense, but with a wind driven device you will always have a higher pressure in front of the blades than you will behind them.
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Old 09-29-10, 07:15 PM   #23
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Quote:
Originally Posted by Sularus65 View Post
Makes sense, but with a wind driven device you will always have a higher pressure in front of the blades than you will behind them.
Isn't that what I said?
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Old 09-30-10, 07:45 AM   #24
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There's a lot of additional info on the web (just google flodesign ) on this turbine which confirms my suspicion that these can be packed much more tightly on a farm and also that the blades you can see at the front are part of the shroud with the actual turbine blades behind these.
They also got their $35M part B funding back in June ( I thought they were only looking for $25M in which case do you think they will forward me $10M for my development of a Megawatt Vawt in a shoebox ? ) Looking at the investors this thing seems to be being taken very seriously despite the failure of a similar NZ design , and others.
Instinct is a poor substitute for science , but I still can't believe a 300 foot diameter , slowly revolving, propellor which has to shutdown just as the wind speed gets up to where its got some real power is the way we should be going . I did a bit of research on the wind power "gurus" who seem to inhabit some of the deepest trenches and they all seem to have some sort of vested interest in the existing technology ( a possible exception being Sangrillo who now has a connection with Helix wind.Big Al

Last edited by Big Al; 09-30-10 at 07:53 AM.. Reason: Just an addition
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Old 01-31-11, 08:14 PM   #25
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The exhaust shape plus the venturi design looks exactly like many of the "hush kits" developed for older jet aircraft so they could meet stage 3 & stage 4 noise levels.
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Old 02-06-11, 07:02 AM   #26
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What would it matter if a vacume is caused behind the blades when there is only so much pressure in front of the blades to begin with? It's not going to pull any more air through than what is available. I would understand if there was a ventura in front of the blades to increase pressure/flow..

The law of leverage is going to be a hard one to beat. long blades = torque. I can move a lot of weight with a cinder block and a 4"x4"..
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Old 02-12-11, 05:22 AM   #27
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OKGK is right. This has to be a scam. Similar ideas have always run into the laws of physics wall. I myself have toyed with the idea of using a chute to squeeze air down so that you can get more out of smaller blades. Problem is as the larger opening of the chute drops in ratio to the smaller opening the efficiency INCREASES. It is more efficient to simply use a larger set of blades. No way their idea works because they will lose a disproportionate amount of energy moving air behind the turbine. And they're trying to extract energy out of the same air that has already moved through the front. No wonder they are so obscure on their proposal. Smoke and mirrors.
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Old 11-29-11, 01:25 PM   #28
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I'm also pretty sceptical. There have been many tries at ducted wind turbines and none have had gains that make the extra materials even close to worth it over the larger counterparts.

Many have also hindered the performance of the blades by themselves.

If you really have an application where you don't have the space to put up the larger counterpart and you're ok taking a big gamble on this, go for it... I just recommend for the average user to stay away until it's proven more effective.

The burden of proof is on them and you can't get that from an ad.
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Old 09-03-12, 12:16 PM   #29
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The first ducted windmill was patented in 1868.
If it was a viable idea, we would be using them today

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