Low Pressure Air: How Is It Made?

In summary: This would be an interesting way to increase lift. 3) This system may also be able to move air downward, which would create lift. 4) It's not clear how this would be able to stabilize a surface for vertical lift.
  • #1
T.O.E Dream
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I know that low pressure air is created when air moves fast, but what other ways are low pressure air made?
 
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  • #2
Can someone correct me if I'm wrong about something. Also, is there even any other way to create low pressure air?
 
  • #3
Increase the volume the air is contained in or drop the temperature.
 
  • #4
So can these strategies be applied to create lift on a surface? For example, you create low pressure air at the top of the surface and high pressure air at the bottom and you can create lift, like in a plane?
 
  • #5
No, since FredGarvin's suggestions apply to air inside a sealed container.
 
  • #6
Punch holes in the upper surface of the wing and suck air through them.
 
  • #7
Or just get a whole bunch of vacuum cleaners. One can pick up a bowling ball. I'll bet 10,000 could lift an airplane.

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  • #8
How does a windmill work...seems like a change in air pressure as it flows over the curveature is at "work" (pun).
 
  • #9
OmCheeto said:
Or just get a whole bunch of vacuum cleaners. One can pick up a bowling ball. I'll bet 10,000 could lift an airplane.

[PLAIN][PLAIN]http://www.carlson-store-fixtures.com/Portals/3/aspdnsf/images/Category/icon/798.jpg [PLAIN][PLAIN]http://www.carlson-store-fixtures.com/Portals/3/aspdnsf/images/Category/icon/798.jpg [PLAIN][PLAIN]http://www.carlson-store-fixtures.com/Portals/3/aspdnsf/images/Category/icon/798.jpg [PLAIN][PLAIN]http://www.carlson-store-fixtures.com/Portals/3/aspdnsf/images/Category/icon/798.jpg

I don't want to lift a plane. I want to create lift.
 
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  • #10
russ_watters said:
Punch holes in the upper surface of the wing and suck air through them.

So you're telling me that if someone we're to punch holes through the wing of an airplane and use vacuums at the top of them, it would create lift?

I know it's not practical but in theory might it be possible?
 
  • #11
T.O.E Dream said:
So you're telling me that if someone we're to punch holes through the wing of an airplane and use vacuums at the top of them, it would create lift?

I know it's not practical but in theory might it be possible?
I don't know if there are any production aircraft that have used the technique, but it is well documented to work - not just in theory.
The experimental wing panel, made mostly of titanium, is perforated with about 10 million nearly microscopic laser-cut holes. An on-board suction system draws off, through the tiny holes, the turbulent layer of air flowing over the wing's surface. Eliminating the layer of rough air creates a laminar flow condition that reduces aerodynamic drag and contributes to fuel savings.
http://www.dfrc.nasa.gov/gallery/Photo/F-16XL2/index.html
 
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  • #12
I think heating the air on top of the wing is one way to go. We should probably put a cover over the top to keep the hot air from getting away. The wing don't have to be moving though the air anymore so we'll just call the wing the 'bottom surface', and the entire contraption a balloon.
 
  • #13
Alternatively high pressure can be develped on bottom surfaces of a craft. A ballistic parachute comes to mind.

While in mid-air or on the ground, fire the parachute high into the air on a long cable. A wench reels in the cable more quickly than the parachute falls. Upon reaching the vehicle the parachute is repacked and the next balistic charge loaded, whereupon the cycle begins again.
 
  • #14
So is there a way we can take all these ideas and create vertical lift. For example, we can "blow" air across the top of a surface and heat air at the bottom of the surface. I understand that it would be hard to stabilize the surface but again in theory.
 
  • #15
T.O.E Dream said:
So is there a way we can take all these ideas and create vertical lift. For example, we can "blow" air across the top of a surface and heat air at the bottom of the surface. I understand that it would be hard to stabilize the surface but again in theory.
It can certainly be done...Why you would want to do that is another question...
 
  • #16
russ_watters said:
http://www.dfrc.nasa.gov/gallery/Photo/F-16XL2/index.html

The intent of this system is to reduce drag by suctioning off the turbulent boundary layer, rather than provide lower pressure--apparently. Although it's still something that can be considered as a means of providing or enhancing lift.

How this is supposed to work, according to the link, is something of a mystery to me. Normally one wants to encourage a turbulent boundary layer to reduce the drag, inherent toward the trailing part of the upper surface, as the boundary separates on encountering an adverse pressure gradient. A turbulent flow will remain attached further along the cord.

1) The article seems to be advertising something useful in supersonic flight, though. 2) With enough suction it may be possible to move the adverse pressure gradient rearward from where it would otherwise detach.
 
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  • #17
What if you took the energy that is required for creating the suction, or heating the wing, and instead used it to provide more thrust to the engines? That would create additional lift as well, and be much simpler to implement.
 
  • #18
russ_watters said:
It can certainly be done...Why you would want to do that is another question...

It might be the start of a new type of transportation. Can it?
 
  • #19
T.O.E Dream said:
It might be the start of a new type of transportation. Can it?

...no.
 
  • #20
T.O.E Dream said:
I know that low pressure air is created when air moves fast, but what other ways are low pressure air made?
Depends why the air is moving fast. Take the simple case of a propeller, as the air passes through the virtual disk formed by the rotating prop it's speed isn't changed much, but the pressure is. The air ahead of the prop accelerates into the low pressure zone in front of the prop, then the pressure is increased, and the air continues to accelerate as it's pressure is reduced back to ambient.

When solids interact with fluids or gasses, both pressure and speed can be changed by that interaction. The exhaust from a jet engine is both high pressure and high speed.

For the fluid or gas flow outside of the region of interaction with a solid, that fluid or gas accelerate from higher pressure zones to lower pressure zones, and the relationship between the change in pressure versus change in speed can be converted into a relationship between static pressure and speed, and this relationship can be approximated by Bernoulli equation (Bernoulli doesn't take turbulent factors into account).

vacuums and wing holes
There are man made "flying saucer" type aircraft that use a set of propellers (vertical axis) located in holes around the aircraft. One of these was demoed at the 1984 Los Angeles Olympics.
 
  • #21
Can someone explain how sucking air through the holes creates lift?
 
  • #22
T.O.E Dream said:
Can someone explain how sucking air through the holes creates lift?
It doesn't. It was done to reduce drag. You can't violate Newtons second and third laws, force = mass x acceleration, forces only exist in equal and opposing pairs. To get lift, an aircraft has to generate a downwards force onto to the air, coexistant with the air exerting an opposing upwards force onto the aircraft. The downwards force applied to the air accelerates the air downwards (and/or compresses it if in ground effects).
 

FAQ: Low Pressure Air: How Is It Made?

How is low pressure air created?

Low pressure air is created through a process called compression. This involves decreasing the volume of a gas, which in turn increases its pressure. In most cases, this is done by using a machine called an air compressor.

What is the difference between low pressure air and high pressure air?

The main difference between low and high pressure air is the amount of force exerted by the gas. Low pressure air has less force due to its lower pressure, while high pressure air has more force due to its higher pressure. This can affect the performance and applications of the air in various systems.

What are some common uses for low pressure air?

Low pressure air has many applications, including in pneumatic tools, air brakes in vehicles, and air conditioning systems. It is also used in industrial processes such as packaging and food processing, as well as in medical equipment like ventilators.

How does low pressure air affect weather patterns?

Low pressure air systems can contribute to the formation of weather patterns, particularly when they interact with high pressure air systems. Low pressure air typically brings cloudy and rainy conditions, while high pressure air brings clear and sunny conditions.

Can low pressure air be dangerous?

While low pressure air itself is not inherently dangerous, it can pose risks if not handled properly. For example, sudden changes in pressure can cause ear or sinus discomfort, and if compressed air is released too quickly, it can cause injury. It is important to follow safety protocols when working with low pressure air to avoid any potential hazards.

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