The discussion revolves around the maximum force that can be generated by compressed air from a typical garage air compressor tank, particularly at a pressure of around 150 psi. Participants explore the impact of nozzle design on force output and the mechanics of air jets, as well as potential applications and experimental approaches.
Participants express various viewpoints regarding the mechanics of air jets and nozzle design, with no consensus reached on the best approach or the maximum achievable force. The discussion remains unresolved with multiple competing ideas and interpretations.
Participants mention that the force output may vary based on nozzle design, air flow characteristics, and the specific application of the compressed air. There are also references to empirical testing methods, such as using a kitchen scale, which may introduce variability based on distance and setup.
This discussion may be of interest to hobbyists experimenting with compressed air applications, engineers exploring fluid dynamics, and individuals curious about the mechanics of air pressure and nozzle design.
Nozzle? What nozzle? Could you explain in more detail what you are asking?bob012345 said:What's the maximum force that air from a typical garage air compressor tank, the kind that's used to inflate tires assuming the pressure is around 150 psi.? Can the force be changed by nozzle design? Thanks.
Sustained force releasing air at standard psi from the kinds of tanks that fill car tires.jackwhirl said:@bob012345, it sounds like you're talking about the force produced by a jet of air. Is that right? Are you interested in peak, or sustained force?
The air nozzle you would normally insert into your tire valve. How much force can one get from that?russ_watters said:Nozzle? What nozzle? Could you explain in more detail what you are asking?
bob012345 said:Sustained force releasing air at standard psi from the kinds of tanks that fill car tires.
Again, do you mean the force from the jet of air from an open nozzle? The nozzle you attach to your tire valve only allows air to flow when the valve is attached to the tire valve...bob012345 said:The air nozzle you would normally insert into your tire valve. How much force can one get from that?
There are two answers to this, depending on what you mean:bob012345 said:The air nozzle you would normally insert into your tire valve. How much force can one get from that?
Thanks. It's more the first case, letting the compressed air expand through a nozzle or device like a rocket. Remember when we were kids and we would take a garden hose with water flowing and by constructing the flow it had a lot more force and the hose would lift itself up. Like a water bottle rocket. I want to play with the way compressed air is released to maximize the force.jackwhirl said:There are two answers to this, depending on what you mean:
From context it sounds like you're talking about a jet of air, in which case you should read about rocket engine nozzles, because the shape of the nozzle most definitely does impact the force output.
The other is the idea that you could use this air to pressurize a bladder of some sort, to lift a large load. (Think something like an air mattress.) In this situation, the force you could apply would be equal to the surface area times the pressure. Thus, 60 inches * 80 inches * 150 pounds per square inch gives you 720,000 pounds.
There's a really big difference between these scenarios. That's why were asking you what you're trying to accomplish. We don't fully understand your question.
Thanks. By your estimate, I'd get 5-10 pounds.russ_watters said:Again, do you mean the force from the jet of air from an open nozzle? The nozzle you attach to your tire valve only allows air to flow when the valve is attached to the tire valve...
Anyway, if that's what you mean though, it is probably something you can estimate by feel; a few pounds of force. A first swag would be to multiply the pressure (maybe 100 psi) by the area (maybe a tenth or 20th of a square inch), but the flow would probably be choked and supersonic, so it would end up being somewhat less.
Right, that is what I was intending.bob012345 said:Thanks. By your estimate, I'd get 5-10 pounds.
A nozzle that expands the flow to ambient pressure will be most efficient. Read that rocket nozzle link I placed above.bob012345 said:Now that we are on the same wavelength, is there any way by clever design I can increase that force for the same air flow? Thanks.
Right, what @jackwhirl said: rockets generate force by giving the reaction mass momentum, so the faster the exit velocity the greater the force. I bet you could get several times the force with a well designed nozzle vs a poor one. But I also expect my estimate is already generous.bob012345 said:Now that we are on the same wavelength, is there any way by clever design I can increase that force for the same air flow? Thanks.
Okay, thanks.russ_watters said:Right, what @jackwhirl said: rockets generate force by giving the reaction mass momentum, so the faster the exit velocity the greater the force. I bet you could get several times the force with a well designed nozzle vs a poor one. But I also expect my estimate is already generous.
Thanks, I will.jackwhirl said:A nozzle that expands the flow to ambient pressure will be most efficient. Read that rocket nozzle link I placed above.
Just to get empirical here, grab a kitchen platform scale and aim the air stream at it.bob012345 said:What's the maximum force that air from a typical garage air compressor tank, the kind that's used to inflate tires assuming the pressure is around 150 psi.? Can the force be changed by nozzle design?
Thanks. Not a bad idea. That's basically what Sir Christopher Cockerell did when he invented the modern hovercraft. Big things can come from little experiments.Tom.G said:Just to get empirical here, grab a kitchen platform scale and aim the air stream at it.
p.s. will vary with distance
Ultimately, I want to use a thin layer of fast moving air to contain a volume of air at higher pressure. That's what early hovercraft did but I want to apply it to a small personal device rather than a large scale multi-ton machine. The compressed air is only for the boundary layer. I hope to lift something like 50 pounds per square foot but only a few inches off the ground.some bloke said:Depending on the length of time you need the force for, you may wish to explore alternative avenues.
Are you referring to a compressor tank, with an air reservoir, or a compact tyre inflator pump?
If you are using the latter, storing the air in a reservoir will allow you to produce a greater force for a short period of time. for example, a pump might only put out a small amount of force, but once my potato gun I had as a kid was pumped up to 180psi, it could fire a chunk of potato half a kilometre (approx.).
If you are looking to achieve some sort of thrust, something like a leaf blower will likely be able to deliver a higher volume of air per second than a compressor. if you were to fit a nozzle to a leaf blower, you'll probably get more thrust than from a compressor, and it will also be lighter due to the lack of a reservoir.
Are you trying to move objects with the compressed air, or move the compressor itself? (IE are you making the launcher or the rocket?)
This appears to me to be completely different from your original question. Is that what you intended or were you thinking one informs to the other or...?bob012345 said:Ultimately, I want to use a thin layer of fast moving air to contain a volume of air at higher pressure. That's what early hovercraft did but I want to apply it to a small personal device rather than a large scale multi-ton machine. The compressed air is only for the boundary layer. I hope to lift something like 50 pounds per square foot but only a few inches off the ground.
One informs the other but I was just answering some bloke. We can stick to the original question on this thread which was basically answered as 5-10 pounds unless someone can suggest how to increase that range. Thanks.russ_watters said:This appears to me to be completely different from your original question. Is that what you intended or were you thinking one informs to the other or...?