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Old 13th February 2014, 08:04 AM   #1
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Default Could a Horn Generate Power?

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According to John Eargle, a horn converts a "high pressure/low volume velocity at the throat into a low pressure/high volume velocity at the mouth."

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If you did it in reverse, could a horn be used to generate power?

For instance, wind turbines do not work effectively where there isn't much wind.
But what if you used a horn to basically "concentrate" the wind into a smaller area?

Basically a horn in reverse, with a turbine at the throat?

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I heard Bruce Thigpen's fan subwoofer at RMAF, so the idea of using a fan at the throat doesn't seem too outrageous.

Here's the article on this technology: http://www.offgridworld.com/funny-lo...wind-turbines/
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Old 13th February 2014, 02:44 PM   #2
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In a way it would work, efficiency on the other hand would be abysmal. Have you ever noticed how wind speed increases it's force between two large buildings? Vertical turbine wind generators can be enhanced in this way.

For air to flow through a device having a intake area 1/2 the exhaust area is considered minimal. Air will only compress so far before it finds a lower resistance path. Principles are used everyday in aircraft cooling systems design.

Gotta say when I saw the title of the thread had to laugh. Just exactly what tangent is Patrick going down now!
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Old 13th February 2014, 02:50 PM   #3
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Sim with fluid dynamics, tis the same as aerodynamics but not compressible.
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Old 13th February 2014, 04:33 PM   #4
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Quote:
Originally Posted by Patrick Bateman View Post
According to John Eargle, a horn converts a "high pressure/low volume velocity at the throat into a low pressure/high volume velocity at the mouth."

If you did it in reverse, could a horn be used to generate power?
But what if you used a horn to basically "concentrate" the wind into a smaller area?
Basically a horn in reverse, with a turbine at the throat?
Decades ago I tested the concept of using horn gain to "amplify" power (which could be generated by solar, wind or any other means), using a very efficient horn loudspeaker run at 60 Hz with a "receiver" loudspeaker as an electrical generator.
Alas, as one would expect, conservation of energy dictated that the output power was less than the input, though the output was 60 Hz AC power.
Converting sound waves to electrical energy using fans or turbines would be even more lossy, as sound is not (should not be) wind.

Alternatively, a horn loudspeaker can pick up ambient (free) sound and the resultant output can be converted in to standard AC power, but as my dad used to say "the problem with free energy is it's so expensive."
The payback on energy returns would probably not occur over the life of the unit.
You can power a calculator's LED display with the rectified output of a very large and expensive loudspeaker from ambient noise, but it only takes a dime-sized PV panel to do the same..

Being from Minnesota, and interested in anything "horn shaped" (and alternative energy), my brother Roy and I had discussed the INVELOX venture many years ago, before the unit pictured was built.

The problem with SheerWind and other venturi type Bernoulli principle wind generators is the structure itself is less efficient in terms of wind energy collection area compared to overall windage in comparison to large rotors.
The swept area of a turbine, equivalent to the propeller diameter, can capture the force of the wind roughly equivalent to a flat disc of the same area.

The collected wind speed is increased in a venturi, allowing smaller turbines running at higher rotational speeds connected to the electrical generator to be employed, yet no net energy gain is seen, other than at speeds that would be too low to start the usual turbine propellor.

Considering the cost of the structure, and the energy to extract from wind is inversely related to speed, it makes more sense to locate generators at locations of high speed wind and distribute high voltage power to use points, than to attempt to extract the little energy available at low average wind speed locations.

The INVELOX/Sheerwind generator you posted is only 1.5 kW to 5 kW.
Below is a 5 kW conventional unit at approximately the same scale, it is obvious which would use less materials for the same generation of power. The standard turbine can also be placed on top of a much taller guyed mast to get it in to the faster upper airspeeds, while raising the venturi type, which has a much lower collection area/windage ratio would require far more non-generating infrastructure.

Art
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Last edited by weltersys; 13th February 2014 at 04:37 PM.
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Old 14th February 2014, 09:01 PM   #5
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Always one step ahead Art!
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Old 14th February 2014, 10:46 PM   #6
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Originally Posted by m R g S r View Post
Always one step ahead Art!
I have made most of the mistakes I advise others against making long ago..
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