Venturi wind turbines

On Tuesday, February 26, 2013 11:12:11 AM UTC-8, amdx wrote:

On 2/25/2013 7:02 PM, Jeff Liebermann wrote:

On Mon, 25 Feb 2013 14:00:28 -0800 (PST), mrdarrett@gmail.com wrote:



Now here's something you don't see every day.



http://machinedesign.com/article/no-more-windmills-wind-catchers-use-venturi-technique-to-generate-power-0222?NL=EET-01&Issue=EET-01_20130225_EET-01_543&YM_RID=mrdarrett@gmail.com&YM_MID=1375571&sfvc4enews=42



http://sheerwind.com

http://sheerwind.com/wp-content/uploads/sheerwind/2012/09/SheerWind-_INVELOX-Info.pdf

http://www.youtube.com/watch?feature=player_embedded&v=elBntB5_TGM

No test results, simulations, numbers, or calculations to be found

anywhere. Hmmmm...



Hey Jeff, it does say they tested a 0.3 watt unit.



"The first small scale field unit, rated 300 mW was designed and

constructed last year and validated the CFD models predictions. A larger

scale field demo unit rated 1.5 kW to 5 kW also went live last year. "



I wonder if the pictures shown are the 1.5 kW unit mentioned above.



Mikek

I do wonder about maintenance though. There's not much friction in clean, smooth PVC pipe, but in real life bugs are going to get sucked in, and those are going to leave sticky residues in the plumbing that will attract dirt, and next thing you know, the friction factor is way up...

Michael

 

On Feb 26, 3:26 pm, mike <ham...@netzero.net> wrote:

On 2/26/2013 11:12 AM, amdx wrote:







On 2/25/2013 7:02 PM, Jeff Liebermann wrote:
On Mon, 25 Feb 2013 14:00:28 -0800 (PST), mrdarr...@gmail.com wrote:

Now here's something you don't see every day.

http://machinedesign.com/article/no-more-windmills-wind-catchers-use-venturi-technique-to-generate-power-0222?NL=EET-01&Issue=EET-01_20130225_EET-01_543&YM_RID=mrdarr...@gmail.com&YM_MID=1375571&sfvc4enews=42

http://sheerwind.com
http://sheerwind.com/wp-content/uploads/sheerwind/2012/09/SheerWind-_....

http://www.youtube.com/watch?feature=player_embedded&v=elBntB5_TGM
No test results, simulations, numbers, or calculations to be found
anywhere. Hmmmm...

Hey Jeff, it does say they tested a 0.3 watt unit.

"The first small scale field unit, rated 300 mW was designed and
constructed last year and validated the CFD models predictions. A larger
scale field demo unit rated 1.5 kW to 5 kW also went live last year. "

I wonder if the pictures shown are the 1.5 kW unit mentioned above.

Mikek

I'd ask 'em the same thing I'd ask Rossi,
"why is it so difficult to prove it?"

Build a uni-directional one out of plywood.
Bolt it to a flatbed truck, or on top of a bus.
Drive it down the road.
Measure volume/pressure with speed as a parameter.
If you like the numbers, stick a generator in it.
Then go solve all those pesky issues with omnidirectional behavior.

Put the intake on a lazy susan, with a weather vane to point it into
the wind.

If you route or switch the exhaust similarly downwind (possibly even
through a reverse Venturi, for comic investor-suckering effect), you
can relieve some of the backpressure too. I dub it the double-synergy
Pushme-pullyou version.

Please send my checks to Emperor Oblahblah and her Moochelleness.
(Saves me the trouble.)

If you can't make it work on a truck driving down the road at
2 or 20 or 60 MPH,
there's no need to pursue it further.

The double-stimulus version could propel the truck faster and faster
without limit. It uses the energy to print foodstamps on switchgrass
paper, with enviro-sustainable 200% economic return. Burn the
foodstamps in its bio-diesel hybrid hyper ion fuel-cell drive, and
you're on your way to wind-powered LEO.

That'd be far more useful than a 300mW prototype.
And you could work on it where there's no wind.
And it'd cost far less and take less time than setting up their website.
But it'd garner fewer greedy/uninformed investors.

--
Cheers,
James Arthur

 

[tm]

<dagmargoodboat@yahoo.com> wrote in message
news:d040147c-71b7-498f-bed9-94cc1a02079e@d11g2000yqe.googlegroups.com...
On Feb 26, 3:26 pm, mike <ham...@netzero.net> wrote:

On 2/26/2013 11:12 AM, amdx wrote:







On 2/25/2013 7:02 PM, Jeff Liebermann wrote:
On Mon, 25 Feb 2013 14:00:28 -0800 (PST), mrdarr...@gmail.com wrote:

Now here's something you don't see every day.

http://machinedesign.com/article/no-more-windmills-wind-catchers-use-venturi-technique-to-generate-power-0222?NL=EET-01&Issue=EET-01_20130225_EET-01_543&YM_RID=mrdarr...@gmail.com&YM_MID=1375571&sfvc4enews=42

http://sheerwind.com
http://sheerwind.com/wp-content/uploads/sheerwind/2012/09/SheerWind-_...

http://www.youtube.com/watch?feature=player_embedded&v=elBntB5_TGM
No test results, simulations, numbers, or calculations to be found
anywhere. Hmmmm...

Hey Jeff, it does say they tested a 0.3 watt unit.

"The first small scale field unit, rated 300 mW was designed and
constructed last year and validated the CFD models predictions. A larger
scale field demo unit rated 1.5 kW to 5 kW also went live last year. "

I wonder if the pictures shown are the 1.5 kW unit mentioned above.

Mikek

I'd ask 'em the same thing I'd ask Rossi,
"why is it so difficult to prove it?"

Build a uni-directional one out of plywood.
Bolt it to a flatbed truck, or on top of a bus.
Drive it down the road.
Measure volume/pressure with speed as a parameter.
If you like the numbers, stick a generator in it.
Then go solve all those pesky issues with omnidirectional behavior.

Put the intake on a lazy susan, with a weather vane to point it into
the wind.

If you route or switch the exhaust similarly downwind (possibly even
through a reverse Venturi, for comic investor-suckering effect), you
can relieve some of the backpressure too. I dub it the double-synergy
Pushme-pullyou version.

Please send my checks to Emperor Oblahblah and her Moochelleness.
(Saves me the trouble.)

If you can't make it work on a truck driving down the road at
2 or 20 or 60 MPH,
there's no need to pursue it further.

The double-stimulus version could propel the truck faster and faster
without limit. It uses the energy to print foodstamps on switchgrass
paper, with enviro-sustainable 200% economic return. Burn the
foodstamps in its bio-diesel hybrid hyper ion fuel-cell drive, and
you're on your way to wind-powered LEO.

That'd be far more useful than a 300mW prototype.
And you could work on it where there's no wind.
And it'd cost far less and take less time than setting up their website.
But it'd garner fewer greedy/uninformed investors.

--
Cheers,
James Arthur

+++++++++++++++++++++++++++++++++++

Oh, oh, oh... It's got the word "stimulus" in it. It simply can't lose. Just
think of the military uses for a LEO wind turbine. Hello, DARPA... hello?

 

[rickman]

On 2/25/2013 8:07 PM, Artemus wrote:

mrdarrett@gmail.com> wrote in message
news:0d341c3d-b898-4e92-bb6a-2ae660938b8e@googlegroups.com...
Now here's something you don't see every day.

http://machinedesign.com/article/no-more-windmills-wind-catchers-use-venturi-technique-to-generate-power-0222?NL=EET-01&Issue=EET-01_20130225_EET-01_543&YM_RID=mrdarrett@gmail.com&YM_MID=1375571&sfvc4enews=42

I'm not an aero engineer but this looks like pie in the sky claims to me.
1. It appears that the intake area on this is significantly less than that of
a propeller style windmill. Therefore it can't extract the same amount
of wind energy. No?

The amount of energy a propeller style windmill can extract is limited
by the design constraints of a propeller. Consider that there is only
one place on the blade where it is moving through the air at the rate
that the wind is moving. Any location closer to the hub will be turning
more slowly pushing the blade faster and any place on the blade further
out will actually be moving faster than the wind, *pushing* the wind
faster and so slowing the blade. There is a term for this, but I don't
remember it. The blade tips are always resisting the motion of the blade.

I think it is theoretically possible to do better. In practice, I
believe the egg beater type blades are more efficient, but I'm not certain.

None of these propeller type designs are 100% efficient. If they were,
they would *stop* the wind, no? Then all that air would just pile up
and have to be shoveled away.

2. There will be not insignificant loss of energy due to the aero drag on
the walls of the venturi. Compressing the air will also add to the losses.

There do appear to be some benefits, but efficiency isn't one of them.

Compared to what?

--

Rick

 

[rickman]

On 2/26/2013 4:45 AM, Jan Panteltje wrote:

On a sunny day (Mon, 25 Feb 2013 14:00:28 -0800 (PST)) it happened
mrdarrett@gmail.com wrote in
0d341c3d-b898-4e92-bb6a-2ae660938b8e@googlegroups.com>:

Now here's something you don't see every day.

http://machinedesign.com/article/no-more-windmills-wind-catchers-use-venturi-technique-to-generate-power-0222?NL=EET-01&Issue=EET
-01_20130225_EET-01_543&YM_RID=mrdarrett@gmail.com&YM_MID=1375571&sfvc4enews=42

Bit of a storm and that whole thing will blow away.
Windmil poles do not catch much wind,
and the propellor blades can be put in neutral position.

Really? What do they do about buildings? Do they fold up in storms too?

--

Rick

 

[rickman]

On 2/26/2013 1:47 PM, John Larkin wrote:

On Tue, 26 Feb 2013 20:32:06 +0200, upsidedown@downunder.com wrote:

On Mon, 25 Feb 2013 14:00:28 -0800 (PST), mrdarrett@gmail.com wrote:

Now here's something you don't see every day.

http://machinedesign.com/article/no-more-windmills-wind-catchers-use-venturi-technique-to-generate-power-0222?NL=EET-01&Issue=EET-01_20130225_EET-01_543&YM_RID=mrdarrett@gmail.com&YM_MID=1375571&sfvc4enews=42

The energy of the wind is directly proportional to the air density and
cross section area and relative to the third power of wind speed.

The cross section area can be the area covered by a conventional
horizontal axis wind turbine or the area covered by some vertical
construction or even the classical Savonius design.

If the structure shown in the picture is 30 m high and maybe 10 m
wide, the cross section area is only 900 m˛, why would anyone expect
it to generate 1.8 MW ? In a lossless system, that would require at
least 18 m/s wind, which is rare at 30 m above ground in most parts of
the world. The situation might be realistic a few hundred meters above
ground.

The basic flaw in arguing that a small structure would concentrate the
air into the turbine. The air is not "so stupid" that it would go
through the turbine, while it can more easily go around the
structure.

Right. The necking down will increase velocity, but also make back
pressure that will reduce the intake volume.

Seems silly.

I think it is funny that you guys think you are aeronautical engineers
too. Do either of you actually know anything about this?

Air doesn't have to be "stupid" to go through a pipe. It happens every
day in the city where wind is redirected and concentrated around
buildings. You see it often in mountain passes.

It's easy to criticize. It's not so easy to understand.

--

Rick

 

[Artemus]

"rickman" <gnuarm@gmail.com> wrote in message news:kgjo0m$ukv$1@dont-email.me...

On 2/26/2013 1:47 PM, John Larkin wrote:
On Tue, 26 Feb 2013 20:32:06 +0200, upsidedown@downunder.com wrote:

On Mon, 25 Feb 2013 14:00:28 -0800 (PST), mrdarrett@gmail.com wrote:

Now here's something you don't see every day.

http://machinedesign.com/article/no-more-windmills-wind-catchers-use-venturi-technique-to-generate-power-0222?NL=EET-01&Issue=EET-01_20130225_EET-01_543&YM_RID=mrdarrett@gmail.com&YM_MID=1375571&sfvc4enews=42

The energy of the wind is directly proportional to the air density and
cross section area and relative to the third power of wind speed.

The cross section area can be the area covered by a conventional
horizontal axis wind turbine or the area covered by some vertical
construction or even the classical Savonius design.

If the structure shown in the picture is 30 m high and maybe 10 m
wide, the cross section area is only 900 m˛, why would anyone expect
it to generate 1.8 MW ? In a lossless system, that would require at
least 18 m/s wind, which is rare at 30 m above ground in most parts of
the world. The situation might be realistic a few hundred meters above
ground.

The basic flaw in arguing that a small structure would concentrate the
air into the turbine. The air is not "so stupid" that it would go
through the turbine, while it can more easily go around the
structure.

Right. The necking down will increase velocity, but also make back
pressure that will reduce the intake volume.

Seems silly.

I think it is funny that you guys think you are aeronautical engineers too. Do
either of you actually know anything about this?

Air doesn't have to be "stupid" to go through a pipe. It happens every day in the
city where wind is redirected and concentrated around buildings. You see it often
in mountain passes.

It's easy to criticize. It's not so easy to understand.

You seem to be very adept at both.
Art

--

Rick

 

[Artemus]

"rickman" <gnuarm@gmail.com> wrote in message news:kgjnjl$t3j$1@dont-email.me...

On 2/25/2013 8:07 PM, Artemus wrote:
mrdarrett@gmail.com> wrote in message
news:0d341c3d-b898-4e92-bb6a-2ae660938b8e@googlegroups.com...
Now here's something you don't see every day.

http://machinedesign.com/article/no-more-windmills-wind-catchers-use-venturi-technique-to-generate-power-0222?NL=EET-01&Issue=EET-01_20130225_EET-01_543&YM_RID=mrdarrett@gmail.com&YM_MID=1375571&sfvc4enews=42

I'm not an aero engineer but this looks like pie in the sky claims to me.
1. It appears that the intake area on this is significantly less than that of
a propeller style windmill. Therefore it can't extract the same amount
of wind energy. No?

The amount of energy a propeller style windmill can extract is limited by the
design constraints of a propeller. Consider that there is only one place on the
blade where it is moving through the air at the rate that the wind is moving. Any
location closer to the hub will be turning more slowly pushing the blade faster and
any place on the blade further out will actually be moving faster than the wind,
*pushing* the wind faster and so slowing the blade. There is a term for this, but
I don't remember it. The blade tips are always resisting the motion of the blade.

***** 100% bullshit. Have you ever even looked at a propeller?
http://woodenpropeller.com/Basic_Propeller_Design.html

I think it is theoretically possible to do better. In practice, I believe the egg
beater type blades are more efficient, but I'm not certain.

None of these propeller type designs are 100% efficient. If they were, they would
*stop* the wind, no?

***** No. Ever hear of a Pelton waterwheel?

Then all that air would just pile up and have to be shoveled away.


2. There will be not insignificant loss of energy due to the aero drag on
the walls of the venturi. Compressing the air will also add to the losses.

There do appear to be some benefits, but efficiency isn't one of them.

Compared to what?

The existing designs. Duh.
Art

 

[John Larkin]

On Tue, 26 Feb 2013 20:38:23 -0500, rickman <gnuarm@gmail.com> wrote:

On 2/26/2013 1:47 PM, John Larkin wrote:
On Tue, 26 Feb 2013 20:32:06 +0200, upsidedown@downunder.com wrote:

On Mon, 25 Feb 2013 14:00:28 -0800 (PST), mrdarrett@gmail.com wrote:

Now here's something you don't see every day.

http://machinedesign.com/article/no-more-windmills-wind-catchers-use-venturi-technique-to-generate-power-0222?NL=EET-01&Issue=EET-01_20130225_EET-01_543&YM_RID=mrdarrett@gmail.com&YM_MID=1375571&sfvc4enews=42

The energy of the wind is directly proportional to the air density and
cross section area and relative to the third power of wind speed.

The cross section area can be the area covered by a conventional
horizontal axis wind turbine or the area covered by some vertical
construction or even the classical Savonius design.

If the structure shown in the picture is 30 m high and maybe 10 m
wide, the cross section area is only 900 m˛, why would anyone expect
it to generate 1.8 MW ? In a lossless system, that would require at
least 18 m/s wind, which is rare at 30 m above ground in most parts of
the world. The situation might be realistic a few hundred meters above
ground.

The basic flaw in arguing that a small structure would concentrate the
air into the turbine. The air is not "so stupid" that it would go
through the turbine, while it can more easily go around the
structure.

Right. The necking down will increase velocity, but also make back
pressure that will reduce the intake volume.

Seems silly.

I think it is funny that you guys think you are aeronautical engineers
too. Do either of you actually know anything about this?

OK, do you claim that the neck down *won't* reduce intake volume?

Air doesn't have to be "stupid" to go through a pipe. It happens every
day in the city where wind is redirected and concentrated around
buildings. You see it often in mountain passes.

It's easy to criticize. It's not so easy to understand.

The thing about inventions like this that they get a lot of press when
they are announced, but nobody notices as they fade into obscurity.

I'd have to wait a couple of years to say "told'ya so!"


--

John Larkin Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation

 

[amdx]

On 2/26/2013 7:38 PM, rickman wrote:

On 2/26/2013 1:47 PM, John Larkin wrote:
On Tue, 26 Feb 2013 20:32:06 +0200, upsidedown@downunder.com wrote:

On Mon, 25 Feb 2013 14:00:28 -0800 (PST), mrdarrett@gmail.com wrote:

Now here's something you don't see every day.

http://machinedesign.com/article/no-more-windmills-wind-catchers-use-venturi-technique-to-generate-power-0222?NL=EET-01&Issue=EET-01_20130225_EET-01_543&YM_RID=mrdarrett@gmail.com&YM_MID=1375571&sfvc4enews=42


The energy of the wind is directly proportional to the air density and
cross section area and relative to the third power of wind speed.

The cross section area can be the area covered by a conventional
horizontal axis wind turbine or the area covered by some vertical
construction or even the classical Savonius design.

If the structure shown in the picture is 30 m high and maybe 10 m
wide, the cross section area is only 900 m˛, why would anyone expect
it to generate 1.8 MW ? In a lossless system, that would require at
least 18 m/s wind, which is rare at 30 m above ground in most parts of
the world. The situation might be realistic a few hundred meters above
ground.

The basic flaw in arguing that a small structure would concentrate the
air into the turbine. The air is not "so stupid" that it would go
through the turbine, while it can more easily go around the
structure.

Right. The necking down will increase velocity, but also make back
pressure that will reduce the intake volume.

Seems silly.

I think it is funny that you guys think you are aeronautical engineers
too. Do either of you actually know anything about this?

Air doesn't have to be "stupid" to go through a pipe. It happens every
day in the city where wind is redirected and concentrated around
buildings. You see it often in mountain passes.

Seems to me what you are saying is, the air is redirected around a
building or through a mountain pass because the building or mountain
wall create a high pressure area, just like the necking down of the
Venturi tube.
Mikek

 

[Gib Bogle]

On 26/02/2013 11:00 a.m., mrdarrett@gmail.com wrote:

Now here's something you don't see every day.

Not very original, but very bogus.

http://en.wikipedia.org/wiki/Compact_wind_acceleration_turbine

Vortec tried something similar in NZ, friends of mine lost money
investing in it.

Richard Flay is a friend who did work for them:
http://www.ipenz.org.nz/ipenz/publications/transactions/Transactions99/EMCh/Phillips.PDF

http://www.windflow.co.nz/news/media-releases/2000-2001/vortec-closure-no-surprise/

 

[Gib Bogle]

On 27/02/2013 9:26 a.m., mike wrote:

On 2/26/2013 11:12 AM, amdx wrote:
On 2/25/2013 7:02 PM, Jeff Liebermann wrote:


I'd ask 'em the same thing I'd ask Rossi,
"why is it so difficult to prove it?"

Build a uni-directional one out of plywood.
Bolt it to a flatbed truck, or on top of a bus.
Drive it down the road.
Measure volume/pressure with speed as a parameter.
If you like the numbers, stick a generator in it.
Then go solve all those pesky issues with omnidirectional behavior.

If you can't make it work on a truck driving down the road at
2 or 20 or 60 MPH,
there's no need to pursue it further.

That'd be far more useful than a 300mW prototype.
And you could work on it where there's no wind.
And it'd cost far less and take less time than setting up their website.
But it'd garner fewer greedy/uninformed investors.

It's a scam.

 

[Gib Bogle]

On 26/02/2013 1:47 p.m., mrdarrett@gmail.com wrote:

The website looks interesting, but it looks like they won't have product shipped until later this year...

http://sheerwind.com/

Minnesota... that's pretty close to you, Tim, right?

Michael

They will never have a product shipped.

 

[rickman]

On 2/27/2013 2:36 PM, John Larkin wrote:

On Tue, 26 Feb 2013 20:38:23 -0500, rickman<gnuarm@gmail.com> wrote:

On 2/26/2013 1:47 PM, John Larkin wrote:
On Tue, 26 Feb 2013 20:32:06 +0200, upsidedown@downunder.com wrote:

On Mon, 25 Feb 2013 14:00:28 -0800 (PST), mrdarrett@gmail.com wrote:

Now here's something you don't see every day.

http://machinedesign.com/article/no-more-windmills-wind-catchers-use-venturi-technique-to-generate-power-0222?NL=EET-01&Issue=EET-01_20130225_EET-01_543&YM_RID=mrdarrett@gmail.com&YM_MID=1375571&sfvc4enews=42

The energy of the wind is directly proportional to the air density and
cross section area and relative to the third power of wind speed.

The cross section area can be the area covered by a conventional
horizontal axis wind turbine or the area covered by some vertical
construction or even the classical Savonius design.

If the structure shown in the picture is 30 m high and maybe 10 m
wide, the cross section area is only 900 m˛, why would anyone expect
it to generate 1.8 MW ? In a lossless system, that would require at
least 18 m/s wind, which is rare at 30 m above ground in most parts of
the world. The situation might be realistic a few hundred meters above
ground.

The basic flaw in arguing that a small structure would concentrate the
air into the turbine. The air is not "so stupid" that it would go
through the turbine, while it can more easily go around the
structure.

Right. The necking down will increase velocity, but also make back
pressure that will reduce the intake volume.

Seems silly.

I think it is funny that you guys think you are aeronautical engineers
too. Do either of you actually know anything about this?

OK, do you claim that the neck down *won't* reduce intake volume?

The point is compared to what? This design works by raising the
velocity of the air in order to make lighter airflows useful. If we are
talking about windspeeds that won't produce useful energy from other
devices and this unit will, then I don't think I care about details like
the pressure in the neck ahead of the turbine.

What is your point?

Air doesn't have to be "stupid" to go through a pipe. It happens every
day in the city where wind is redirected and concentrated around
buildings. You see it often in mountain passes.

It's easy to criticize. It's not so easy to understand.

The thing about inventions like this that they get a lot of press when
they are announced, but nobody notices as they fade into obscurity.

I'd have to wait a couple of years to say "told'ya so!"

What exactly is it that you are telling me? So far all I've read is
"Seems silly". Does that mean you think the company won't succeed?
That is very likely just based on the odds. Only 1 in 5 new small
businesses even make it for five years. So yes, the odds are with you.
There are tons of reasons why companies fail even if their basic idea
is sound.

I don't see any engineering flaws that can't be overcome. Someone said
this will blow away in a hurricane. Yes, if it has high enough winds,
anything will blow away, like houses, trees, light posts. That is just
a design tradeoff. How much money vs. how high winds it will take. I
have no doubt that this structure *can* be built to withstand a 20 year
storm (assuming the device is expected to run for 20 years, that seems a
reasonable target). What it costs I can't say, I'm not a mechanical or
civil engineer.

I'll be looking forward to seeing how well this progresses rather than
being a doubting Thomas expecting it to fail.

--

Rick

 

On Wed, 27 Feb 2013 11:36:08 -0800, John Larkin
<jlarkin@highlandtechnology.com> wrote:

On Tue, 26 Feb 2013 20:38:23 -0500, rickman <gnuarm@gmail.com> wrote:

On 2/26/2013 1:47 PM, John Larkin wrote:
On Tue, 26 Feb 2013 20:32:06 +0200, upsidedown@downunder.com wrote:

On Mon, 25 Feb 2013 14:00:28 -0800 (PST), mrdarrett@gmail.com wrote:

Now here's something you don't see every day.

http://machinedesign.com/article/no-more-windmills-wind-catchers-use-venturi-technique-to-generate-power-0222?NL=EET-01&Issue=EET-01_20130225_EET-01_543&YM_RID=mrdarrett@gmail.com&YM_MID=1375571&sfvc4enews=42

The energy of the wind is directly proportional to the air density and
cross section area and relative to the third power of wind speed.

The cross section area can be the area covered by a conventional
horizontal axis wind turbine or the area covered by some vertical
construction or even the classical Savonius design.

If the structure shown in the picture is 30 m high and maybe 10 m
wide, the cross section area is only 900 m˛, why would anyone expect
it to generate 1.8 MW ? In a lossless system, that would require at
least 18 m/s wind, which is rare at 30 m above ground in most parts of
the world. The situation might be realistic a few hundred meters above
ground.

The basic flaw in arguing that a small structure would concentrate the
air into the turbine. The air is not "so stupid" that it would go
through the turbine, while it can more easily go around the
structure.

Right. The necking down will increase velocity, but also make back
pressure that will reduce the intake volume.

Seems silly.

I think it is funny that you guys think you are aeronautical engineers
too. Do either of you actually know anything about this?

OK, do you claim that the neck down *won't* reduce intake volume?


Air doesn't have to be "stupid" to go through a pipe. It happens every
day in the city where wind is redirected and concentrated around
buildings. You see it often in mountain passes.

It's easy to criticize. It's not so easy to understand.

The thing about inventions like this that they get a lot of press when
they are announced, but nobody notices as they fade into obscurity.

*AFTER* they've sucked the public teat dry and moved onto the next.

I'd have to wait a couple of years to say "told'ya so!"

Good enough now.

 

On Monday, February 25, 2013 6:19:11 PM UTC-5, John Larkin wrote:

On Mon, 25 Feb 2013 14:00:28 -0800 (PST), mrdarrett@gmail.com wrote:



Now here's something you don't see every day.



http://machinedesign.com/article/no-more-windmills-wind-catchers-use-venturi-technique-to-generate-power-0222?NL=EET-01&Issue=EET-01_20130225_EET-01_543&YM_RID=mrdarrett@gmail.com&YM_MID=1375571&sfvc4enews=42



Looks expensive. And it will blow away in a good thunderstorm.



Does that actually work, necking down a pipe to increase air velocity?

You think that's fragile, look at this monster http://en.wikipedia.org/wiki/Solar_updraft_tower

 

On Monday, February 25, 2013 5:00:28 PM UTC-5, mrda...@gmail.com wrote:

Now here's something you don't see every day.



http://machinedesign.com/article/no-more-windmills-wind-catchers-use-venturi-technique-to-generate-power-0222?NL=EET-01&Issue=EET-01_20130225_EET-01_543&YM_RID=mrdarrett@gmail.com&YM_MID=1375571&sfvc4enews=42

It seems to be a fundamentally flawed design:
"Martin Hansen, a wind energy expert at the Technical University of Denmark, disagrees. He says INVELOX will draw in and speed up the wind as claimed, but when the turbine is placed inside the ductwork it will create such high pressure that little additional air will be drawn into the device, making it a poor alternative to conventional turbine designs."
http://m.technologyreview.com/view/508136/ducted-wind-turbines-an-energy-game-changer/

 

[Gib Bogle]

On 27/02/2013 7:47 a.m., John Larkin wrote:

Right. The necking down will increase velocity, but also make back
pressure that will reduce the intake volume.

Seems silly.

It may seem silly to you, but it's a great money-spinner for someone,
apparently. It will generate cash-flow, but no electrical power.

 

[rickman]

On 2/27/2013 3:12 PM, amdx wrote:

On 2/26/2013 7:38 PM, rickman wrote:

Air doesn't have to be "stupid" to go through a pipe. It happens every
day in the city where wind is redirected and concentrated around
buildings. You see it often in mountain passes.

Seems to me what you are saying is, the air is redirected around a
building or through a mountain pass because the building or mountain
wall create a high pressure area, just like the necking down of the
Venturi tube.
Mikek

I wouldn't say the air moves through the narrowing *because* the
pressure rises. The air moves through the narrowing because it, like
anything moving that has mass, has inertia. It takes energy to redirect
the movement. So something has to exert a force on it. If the shape of
the opening is right that force will direct some of it into the
narrowing at a higher speed rather than directing it all around the
obstruction.

Notice that on the images of the Windshear pages the center of the upper
tube has a very long taper that brings the flow from all directions
together in the pipe. The airflow would have to reverse direction to
flow up the pipe towards one of the other intakes. Of course some air
will always leak out, but most of it will continue down the pipe at
increasing velocity.

The part I don't get is why they talk about the final portion of the
pipe ahead of the generator being a Venturi effect. I guess they are
referring to the fact that the air flows faster. I always have thought
of the Venturi effect being about the reduction in pressure.

--

Rick

 

[rickman]

On 2/26/2013 10:02 PM, Artemus wrote:

"rickman"<gnuarm@gmail.com> wrote in message news:kgjnjl$t3j$1@dont-email.me...
On 2/25/2013 8:07 PM, Artemus wrote:
mrdarrett@gmail.com> wrote in message
news:0d341c3d-b898-4e92-bb6a-2ae660938b8e@googlegroups.com...
Now here's something you don't see every day.

http://machinedesign.com/article/no-more-windmills-wind-catchers-use-venturi-technique-to-generate-power-0222?NL=EET-01&Issue=EET-01_20130225_EET-01_543&YM_RID=mrdarrett@gmail.com&YM_MID=1375571&sfvc4enews=42

I'm not an aero engineer but this looks like pie in the sky claims to me.
1. It appears that the intake area on this is significantly less than that of
a propeller style windmill. Therefore it can't extract the same amount
of wind energy. No?

The amount of energy a propeller style windmill can extract is limited by the
design constraints of a propeller. Consider that there is only one place on the
blade where it is moving through the air at the rate that the wind is moving. Any
location closer to the hub will be turning more slowly pushing the blade faster and
any place on the blade further out will actually be moving faster than the wind,
*pushing* the wind faster and so slowing the blade. There is a term for this, but
I don't remember it. The blade tips are always resisting the motion of the blade.

***** 100% bullshit. Have you ever even looked at a propeller?
http://woodenpropeller.com/Basic_Propeller_Design.html

This page is about a propeller. For moving an airplane and such. Try
using the wind to turn it. The picture changes greatly. I have read
some on this and that is what I was speaking from. I looked at some of
the numbers related to wind energy and it is not viable with most
designs unless you get very high up and/or are in a place with good
winds most of the time. That is nowhere near me.

Have you checked out any info on using the wind to turn a propeller.
Have you noticed that the shape of the propeller you linked to is *very*
different from the blades of a windmill? When you figure out why, you
will understand what I wrote.

I think it is theoretically possible to do better. In practice, I believe the egg
beater type blades are more efficient, but I'm not certain.

None of these propeller type designs are 100% efficient. If they were, they would
*stop* the wind, no?

***** No. Ever hear of a Pelton waterwheel?

What is that about? I have no idea what point you are trying to make
referring to a water wheel when we are discussing windmills.

Then all that air would just pile up and have to be shoveled away.


2. There will be not insignificant loss of energy due to the aero drag on
the walls of the venturi. Compressing the air will also add to the losses.

There do appear to be some benefits, but efficiency isn't one of them.

Compared to what?

The existing designs. Duh.

With no real info on either existing designs or the design in question,
it is hard to justify such a statement. The claim made, that it will
operate with winds as slow as 2 MPH would provide energy when a windmill
won't even turn. So which is more efficient?

--

Rick