Venturi wind turbines

[Jamie]

rickman wrote:

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.

It is a reduction in pressure. As soon as it escapes the orifice, the

opening is larger and thus creates negative pressure.

I did look at the post and going by memory, the exit point after the
orifice is larger, which makes perfect sense to me.

Jamie

 

[rickman]

On 2/27/2013 6:46 PM, Jamie wrote:

rickman wrote:

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.

It is a reduction in pressure. As soon as it escapes the orifice, the
opening is larger and thus creates negative pressure.

I did look at the post and going by memory, the exit point after the
orifice is larger, which makes perfect sense to me.

Ok, that makes sense. We'll see how they do this year when they say
they will ship machines. I expect they will start with a middling size,
not MW, but some 10's or 100's of kW for smaller installations. I would
like to see smaller units that could be installed for individuals, but
the economies may not be there after installation costs. I have a place
that is rather remote and loses power from time to time. I'd like to
have something so I'm not without water. I'd also like to pump energy
back into the grid for the credit. If this works, it won't be on
everybody's roof like PV can be, but many of us who have some space
around our property could do this at a hopefully lower cost... according
to their claims.

We'll see.

--

Rick

 

[miso]

Build a uni-directional one out of plywood.

http://www.mariah-energy.com/vertical-axis-wind-turbine-systems/vertical-vs-horizontal-performance/

The above link is for vertical axis wind power. They are unidirectional.
This is kind of like arguing rotary engine versus pistons. They each
have their advantages. Mariah as a company has gone through a few owners.

They have/had (I haven't been there for two years) a small Mariah
vertical wind power generator by the Marin Civic Auditorium. The
vertical units are far more likely to be able to get past city councils
than the horizontal units.

Regarding keeping wind power running 24 and 7, that is not the
objective. In the all of the above strategy, you just put the clean
power on the grid when you have it and throttle back the "dirty" sources
like coal and nuclear.

You also have to look at this as a zero-sum game. A small amount of
clean power allows quite a few new "dirty" cars to be put on the road.
While I wish electric car manufacturers all the best, I think internal
combustion engines are going to be around for a while. I read that the
small solar array they put up near Nellis AFB in Las Vegas prevents the
amount of greenhouse gases equivalent to about 160k cars.

 

On Wednesday, February 27, 2013 1:49:22 PM UTC-8, bloggs.fred...@gmail.com wrote:

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

"The chimney had a height of 195 metres (640 ft) and a diameter of 10 metres (33 ft) with a collection area (greenhouse) of 46 hectares (110 acres) and a diameter of 244 metres (801 ft), obtaining a maximum power output of about 50 kW."

50 kW... 110 acres... wow.

Now, a greenhouse of 110 acres would be pretty neat, actually... especially someplace really cold...

 

On Thu, 28 Feb 2013 12:13:36 +1300, Gib Bogle <g.bogle@auckland.ac.nz>
wrote:

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.

IOW, the epitome of a "stimulus" project.

 

[Greegor]

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

http://sheerwind.com/

Gib Bogle > They will never have a product shipped.

Can a giant funnel with vanes inside be patented?

I can picture a huge funnel like scoop on the
top of an old farm windmill tower, aimed into
the wind by a big tail vane and a fixed wind pipe
through the center of the tower connected to
the wind tube at back of funnel by a slipping ring joint.

The sheerwind design looks like it eliminates
the moving parts with an omnidirectional
input funnel with vanes.

Can such a thing be patented?
Didn't such omnidirectional wind catchers
exist before?

 

[Gib Bogle]

On 28/02/2013 2:40 p.m., Greegor wrote:

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

http://sheerwind.com/

Gib Bogle > They will never have a product shipped.

Can a giant funnel with vanes inside be patented?

I can picture a huge funnel like scoop on the
top of an old farm windmill tower, aimed into
the wind by a big tail vane and a fixed wind pipe
through the center of the tower connected to
the wind tube at back of funnel by a slipping ring joint.

The sheerwind design looks like it eliminates
the moving parts with an omnidirectional
input funnel with vanes.

Can such a thing be patented?
Didn't such omnidirectional wind catchers
exist before?

It's all been tried, unsuccessfully (from the investors' point of view).
http://en.wikipedia.org/wiki/Compact_wind_acceleration_turbine

 

[John Larkin]

On Wed, 27 Feb 2013 16:11:06 -0800 (PST), mrdarrett@gmail.com wrote:

On Wednesday, February 27, 2013 1:49:22 PM UTC-8, bloggs.fred...@gmail.com wrote:
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


"The chimney had a height of 195 metres (640 ft) and a diameter of 10 metres (33 ft) with a collection area (greenhouse) of 46 hectares (110 acres) and a diameter of 244 metres (801 ft), obtaining a maximum power output of about 50 kW."

50 kW... 110 acres... wow.

Now, a greenhouse of 110 acres would be pretty neat, actually... especially someplace really cold...

You could maybe grow stuff in that greenhouse and burn it. Or eat it.


--

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

 

On Feb 26, 8:24 pm, "tm" <No_one_h...@white-house.gov> wrote:

dagmargoodb...@yahoo.com> wrote in message
On Feb 26, 3:26 pm, mike <ham...@netzero.net> 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.

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.

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

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?

(Oh, darn--I forgot to paint it green.)

James

 

[Artemus]

"rickman" <gnuarm@gmail.com> wrote in message news:kgm5p0$a8q$1@dont-email.me...

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.

Thanks. I didn't know that. Got a link?

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.

Pelton wheels reverse the water flow for greater efficiency compared with
just stopping the flow.
Art

 

On Wednesday, February 27, 2013 7:11:06 PM UTC-5, mrda...@gmail.com wrote:

Now, a greenhouse of 110 acres would be pretty neat, actually... especially someplace really cold...

Well they have this indoor rainforest in Iowa http://www.earthpark.net/about/faqs.php
can't tell if it was completed or not, didn't go over too well with fiscal conservatives.

 

[rickman]

On 2/28/2013 8:39 PM, Artemus wrote:

"rickman"<gnuarm@gmail.com> wrote in message news:kgm5p0$a8q$1@dont-email.me...
On 2/26/2013 10:02 PM, Artemus wrote:
"rickman"<gnuarm@gmail.com> wrote in message news:kgjnjl$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.

Thanks. I didn't know that. Got a link?

No, I read this a couple of years ago when I took a look at installing
solar or wind generation. Paying someone to install a system is pretty
pricey and it doesn't pay for itself for decades, if ever. I hear the
Chinese have dramatically dropped the price of PV solar equipment, but
we are putting a *huge* surcharge on it because we claim dumping.
Meanwhile Germany is installing them hand over fist.

I don't recall all the details of windmills, the swept area is
important, but the propeller design has some built-in contradictions
like this velocity thing that limits efficiency. I hope I'm not
remembering it wrong. Sometimes that happens... lol

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.

Pelton wheels reverse the water flow for greater efficiency compared with
just stopping the flow.

That would be nice if it could be done with wind. Maybe it can, but
wind is over a large area so how do you turn it around? The Pelton
wheel wouldn't work in a river, it works with a directed stream. It's
possible this concept could be applied to the Windshear design at the
generator. At that point the wind is a higher speed stream like the
spout of the Pelton water wheel. Who knows? A lot depends on the details.

Even so, just how much of the energy of the flowing water is turned into
motion of the wheel? If the wheel reaches the speed of the flowing
water, it no longer pushes on the wheel. If the Pelton can shoot the
water back out at the same speed it impacts the water wheel, it should
read optimum efficiency with the paddles moving at half the speed of the
water jet. Then the water rebounding from the wheel is stopped dead and
falls... or something. What do you do with the water? It would tend to
pile up. If you do that with the wind, it would also pile up. So you
just can't get all the energy from the wind, it has to leave some to
move the air out of the way to allow for more wind... no?

--

Rick

 

[Charlie E.]

On Mon, 04 Mar 2013 00:15:58 -0500, rickman <gnuarm@gmail.com> wrote:

On 2/28/2013 8:39 PM, Artemus wrote:
"rickman"<gnuarm@gmail.com> wrote in message news:kgm5p0$a8q$1@dont-email.me...
On 2/26/2013 10:02 PM, Artemus wrote:

Pelton wheels reverse the water flow for greater efficiency compared with
just stopping the flow.

That would be nice if it could be done with wind. Maybe it can, but
wind is over a large area so how do you turn it around? The Pelton
wheel wouldn't work in a river, it works with a directed stream. It's
possible this concept could be applied to the Windshear design at the
generator. At that point the wind is a higher speed stream like the
spout of the Pelton water wheel. Who knows? A lot depends on the details.

Even so, just how much of the energy of the flowing water is turned into
motion of the wheel? If the wheel reaches the speed of the flowing
water, it no longer pushes on the wheel. If the Pelton can shoot the
water back out at the same speed it impacts the water wheel, it should
read optimum efficiency with the paddles moving at half the speed of the
water jet. Then the water rebounding from the wheel is stopped dead and
falls... or something. What do you do with the water? It would tend to
pile up. If you do that with the wind, it would also pile up. So you
just can't get all the energy from the wind, it has to leave some to
move the air out of the way to allow for more wind... no?

Rick,
With a Pelton wheel, you use it in a special housing. A nozzle
directs the flow on to the wheel, which has blades shaped like two
half circles joined together. (If you have already looked up the
Pelton wheel, please forgive me...) The water flow hits at the point
of the join, where the water is first directed sideways, and then
backwards so the water flows in two fans to either side of the
original jet. A basin and drain below catches the water and drains
it, so there is not 'backflow' to deal with. The blades should be
spinning in air.

 

[mike]

On 3/4/2013 11:31 AM, Charlie E. wrote:

On Mon, 04 Mar 2013 00:15:58 -0500, rickman<gnuarm@gmail.com> wrote:

On 2/28/2013 8:39 PM, Artemus wrote:
"rickman"<gnuarm@gmail.com> wrote in message news:kgm5p0$a8q$1@dont-email.me...
On 2/26/2013 10:02 PM, Artemus wrote:

Pelton wheels reverse the water flow for greater efficiency compared with
just stopping the flow.

That would be nice if it could be done with wind. Maybe it can, but
wind is over a large area so how do you turn it around? The Pelton
wheel wouldn't work in a river, it works with a directed stream. It's
possible this concept could be applied to the Windshear design at the
generator. At that point the wind is a higher speed stream like the
spout of the Pelton water wheel. Who knows? A lot depends on the details.

Even so, just how much of the energy of the flowing water is turned into
motion of the wheel? If the wheel reaches the speed of the flowing
water, it no longer pushes on the wheel. If the Pelton can shoot the
water back out at the same speed it impacts the water wheel, it should
read optimum efficiency with the paddles moving at half the speed of the
water jet. Then the water rebounding from the wheel is stopped dead and
falls... or something. What do you do with the water? It would tend to
pile up. If you do that with the wind, it would also pile up. So you
just can't get all the energy from the wind, it has to leave some to
move the air out of the way to allow for more wind... no?

Rick,
With a Pelton wheel, you use it in a special housing. A nozzle
directs the flow on to the wheel, which has blades shaped like two
half circles joined together. (If you have already looked up the
Pelton wheel, please forgive me...) The water flow hits at the point
of the join, where the water is first directed sideways, and then
backwards so the water flows in two fans to either side of the
original jet. A basin and drain below catches the water and drains
it, so there is not 'backflow' to deal with. The blades should be
spinning in air.

Imagine a water-powered Pelton wheel operating in water and you'll
appreciate why an air-powered Pelton wheel doesn't work in air.

 

[amdx]

On 2/28/2013 6:47 PM, bloggs.fredbloggs.fred@gmail.com wrote:

On Wednesday, February 27, 2013 7:11:06 PM UTC-5, mrda...@gmail.com wrote:

Now, a greenhouse of 110 acres would be pretty neat, actually... especially someplace really cold...

Well they have this indoor rainforest in Iowa http://www.earthpark.net/about/faqs.php
can't tell if it was completed or not, didn't go over too well with fiscal conservatives.

As a fiscal conservative, I have no problem with interesting projects.

Private money can.. it is private money right? I mean let's not waste
taxpayer money.
Mikek

 

[Tim Williams]

"mike" <ham789@netzero.net> wrote in message
news:kh31pe$qo8$1@dont-email.me...

Imagine a water-powered Pelton wheel operating in water and you'll
appreciate why an air-powered Pelton wheel doesn't work in air.

The air-powered version might work in a *vacuum*, but (depending on the
grade of vacuum) there are things that do better already, e.g.,
turbomolecular pumps (for very little gas, of course).

Tim

--
Deep Friar: a very philosophical monk.
Website: http://seventransistorlabs.com

 

On Thursday, February 28, 2013 4:47:51 PM UTC-8, bloggs.fred...@gmail.com wrote:

On Wednesday, February 27, 2013 7:11:06 PM UTC-5, mrda...@gmail.com wrote:



Now, a greenhouse of 110 acres would be pretty neat, actually... especially someplace really cold...



Well they have this indoor rainforest in Iowa http://www.earthpark.net/about/faqs.php

can't tell if it was completed or not, didn't go over too well with fiscal conservatives.

What, they were asking for taxpayer funding for it?

 

On Monday, March 4, 2013 2:51:01 PM UTC-8, amdx wrote:

On 2/28/2013 6:47 PM, bloggs.fredbloggs.fred@gmail.com wrote:

On Wednesday, February 27, 2013 7:11:06 PM UTC-5, mrda...@gmail.com wrote:



Now, a greenhouse of 110 acres would be pretty neat, actually... especially someplace really cold...



Well they have this indoor rainforest in Iowa http://www.earthpark.net/about/faqs.php

can't tell if it was completed or not, didn't go over too well with fiscal conservatives.



As a fiscal conservative, I have no problem with interesting projects.

Private money can.. it is private money right? I mean let's not waste

taxpayer money.

Mikek

Same here.

The implication was it was taxpayer money; otherwise, why would fiscal conservatives worry about it...?