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Forces On Toroidal Wind Tunnel when Wing is attached inside?
by
StoyanNikolov
on 09 May, 2023 19:25
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Consider the attached Toroidal wind Tunnel.
21Y_ahnn4tbj5ko3c.jpg
The Wind tunnel is in Vacuum and the moving air and the attached wing are only inside the toroidal tunnel.
Will the mounted wing on the walls of the tunnel experience force and move the Toroidal tunnel as shown in the picture.
Thank you.
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#1
by
Jim
on 09 May, 2023 20:07
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No. There is zero sum of forces on the tunnel structure
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#2
by
DanClemmensen
on 09 May, 2023 20:55
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Angular momentum is conserved. The fan within the torus is blowing the air around the torus and is fixed to the torus. Wind going clockwise will cause the torus to rotate counterclockwise. the wing makes no difference except perhaps to slightly change the direction of the axes of rotation.
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#3
by
StoyanNikolov
on 09 May, 2023 20:58
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Angular momentum is conserved. The fan within the torus is blowing the air around the torus and is fixed to the torus. Wind going clockwise will cause the torus to rotate counterclockwise. the wing makes no difference except perhaps to slightly change the direction of the axes of rotation.
Thanks for the reply.
Will the part with attached wing start moving somewhere ?
As a result of lift force. Except angular movement?
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#4
by
Jim
on 09 May, 2023 21:01
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Angular momentum is conserved. The fan within the torus is blowing the air around the torus and is fixed to the torus. Wind going clockwise will cause the torus to rotate counterclockwise. the wing makes no difference except perhaps to slightly change the direction of the axes of rotation.
Thanks for the reply.
Will the part with attached wing start moving somewhere ?
As a result of lift force. Except angular movement?
What is blowing the air?
Lift force has no effect
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#5
by
StoyanNikolov
on 09 May, 2023 21:03
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Angular momentum is conserved. The fan within the torus is blowing the air around the torus and is fixed to the torus. Wind going clockwise will cause the torus to rotate counterclockwise. the wing makes no difference except perhaps to slightly change the direction of the axes of rotation.
Thanks for the reply.
Will the part with attached wing start moving somewhere ?
As a result of lift force. Except angular movement?
What is blowing the air?
Lift force has no effect
Lets say there is fan on the opposite side
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#6
by
Jim
on 09 May, 2023 21:10
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Angular momentum is conserved. The fan within the torus is blowing the air around the torus and is fixed to the torus. Wind going clockwise will cause the torus to rotate counterclockwise. the wing makes no difference except perhaps to slightly change the direction of the axes of rotation.
Thanks for the reply.
Will the part with attached wing start moving somewhere ?
As a result of lift force. Except angular movement?
What is blowing the air?
Lift force has no effect
Lets say there is fan on the opposite side
No matter what scheme you come up with, an airfoil on the interior will cause no movement of the tube. This is basic physics.
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#7
by
Twark_Main
on 18 May, 2023 06:14
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Can we finally just mercifully rename this
New Physics for Space Technology forum to what it really is, "Teach People Physics 101 Conservation Laws, Because Clearly The Public Education System Doesn't?"
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#8
by
Hobbes-22
on 18 May, 2023 07:30
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The air imparts an upward force on the wing. However, you can see in your diagram that the wing influences the airflow around it, which means the air also imparts a force on the tunnel walls. These two cancel each other out.
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#9
by
chazemz
on 21 May, 2023 12:52
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Maybe it would be useful to "educate" people on what a forum is. To exchange ideas whether they be correct or not, is not a bad thing. I for one do not want to be "educated" so that I believe in only a single point of view. Hubris is not something to be encouraged. On topic, if you apply a force at the point of the wing the object will simply rotate.
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#10
by
Coastal Ron
on 21 May, 2023 13:21
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I for one do not want to be "educated" so that I believe in only a single point of view.
The laws of physics are not a "point of view". And while scientific theories can change over time, the abundance of facts that support current theories should be respected and studied, not discarded because they are inconvenient.
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#11
by
chazemz
on 21 May, 2023 13:51
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You seem to be edging your bets being in the "laws of physics" and the "theories of physics" camps at the same time. You mention the word "respect". The person posting should be shown some respect. Deriding some ones idea is disrespectful. If you have greater knowledge, then share that knowledge on this forum. By all means use known physics in your argument but always keep an open mind.
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#12
by
Coastal Ron
on 21 May, 2023 19:53
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You seem to be edging your bets being in the "laws of physics" and the "theories of physics" camps at the same time.
No, I'm not, because you were misread what I wrote. If you would have quoted what I wrote, like I'm doing with you, then you would have caught your mistake - I never wrote "theories of physics", I wrote "scientific theories", which Wikipedia defines as:
A scientific theory is an explanation of an aspect of the natural world and universe that has been repeatedly tested and corroborated in accordance with the scientific method, using accepted protocols of observation, measurement, and evaluation of results. Where possible, theories are tested under controlled conditions in an experiment.[1][2] In circumstances not amenable to experimental testing, theories are evaluated through principles of abductive reasoning. Established scientific theories have withstood rigorous scrutiny and embody scientific knowledge.
Then you wrote:
You mention the word "respect". The person posting should be shown some respect.
Respect can be demanded, but it has to be earned.
Deriding some ones idea is disrespectful.
Disrespecting the HUGE body of knowledge regarding physics is something you think should be encouraged?
If you have greater knowledge, then share that knowledge on this forum. By all means use known physics in your argument but always keep an open mind.
I responded to your post because I didn't think you were respecting the time NSF members took to respond to the original poster.
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#13
by
chazemz
on 22 May, 2023 07:39
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So that you know what camp I am in. There are no "laws of physics" only theories of physics. Physics is a science not a religion. I have disrespected no one and if I was after respect I would certainly not demand it. Anyway back to topic. I agree with the earlier comments. You have to account for the effects of the mechanism that produces the airflow.
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#14
by
laszlo
on 22 May, 2023 10:17
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So when did pointing out that someone is wrong become "disrespectful"? I've been noticing that attitude a lot lately - you don't agree with me, therefore you don't respect me, even if I'm patently wrong.
As far as there being no laws of physics, is anyone willing to bet that if I let go of a 30 kilo anvil 1 meter above their bare foot on the sidewalk in front of Buckingham Palace, with only air intervening, that needing medical attention is only a theory that can be gotten around?
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#15
by
chazemz
on 22 May, 2023 11:10
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Suggesting that anyone who posts on this forum has been failed by an education system is disrespectful.
If you want to drop an anvil on your foot, go ahead. Why would you want to do it in front of Buckingham Palace? it is a long walk down the mall carrying 30kg. May I advise you not to do it when the ambulance staff are on strike. Back to topic. What you need to ask yourself is if you placed a fan and a wing structure inside a sealed box and turned the fan on, what would be the outcome. If the box was placed on a weight scale, would the weight decrease according to the scale when the fan is switched on? If the fan were powerful enough would the box lift off the ground?
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#16
by
rfdesigner
on 22 May, 2023 12:36
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So that you know what camp I am in. There are no "laws of physics" only theories of physics. Physics is a science not a religion. I have disrespected no one and if I was after respect I would certainly not demand it. Anyway back to topic. I agree with the earlier comments. You have to account for the effects of the mechanism that produces the airflow.
Actually, it's worth digging a little deeper into how the physics "law" works, lets look at an example:
1: observations are made about the world around us, lets say we all agree that the world in our immediate vicinity appears flat so the whole world is flat
This is wrong, but lots of human activity, like building houses, factories, roads etc are built every year that do not take account of the roundness of the earth. For those exercises the earth is treated as flat, and it's good enough.
2: further observations are made and show the earth curves away from us in every direction, our measurements indicate this curve is fairly constant, so we decide the earth is spherical
This is also wrong, but less so. It's good enough to fly aircraft around the world picking efficient flight routes, for making maps of the world and so on. We could also build houses accounting for the roundness of the earth but the difference is so miniscule we don't do it. But long suspension bridges do take account of the earths roundness.
3: more observations indicate that the spin of the earth causes it to bulge a little around the centre, so we are going to update our model to oblate spheroid, this also aligns with observations showing variation in weight vs latitude.
This is also wrong, but less than the sphere, this influences paths of spacecraft in orbit. Nothing to stop us building houses including the oblate spheroid model too.. but even less difference would be noticed.
4: further observations show regions to be higher or lower than others, these are not just mountain ranges, but areas much larger and influence.
What we have here is an example of "physics theories" that get ovrturned, but notice the first theory is still valid, but only within a limited specified area. This is about more or less accurate physics, over time the models get better at describing the world around us, the original models ARE STILL VALID.. within their own limitations, but when we want to go further we need the improved models. Going back to the original post of a wing in a torus, this is all settled physics, somewhere between flat earth and spherical earth, there's no high energy, extreme gravity, bending light, dilating time, going on, Schrodinger's nowhere to be seen and dark matter or energy aren't relevant. The physics is settled.... we could do the maths using Newtonian mechanics or general relativity and we'd get the same answer, to any meaningful level of accuracy.
To go back to your "there are no laws" part. I think you need to re-evaluate that, because it's going to get you in trouble with the way you think about things. We are all open to new theories, but they need to not just throw the last 350 years of observations in the bin.
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#17
by
chazemz
on 22 May, 2023 13:03
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May I commend you on the way you have worded your reply. Physics must be open to challenge and on a personal level I see "law of physics" as restrictive. "Theories of physics" leaves everything open to question, which is what people on this forum are trying to do. Whether they succeed, time will tell.
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#18
by
Coastal Ron
on 22 May, 2023 14:00
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Physics must be open to challenge...
Modern day science IS open to change, but only if that change is backed up with data. So far no data has been provided for the topic of this thread.
...and on a personal level I see "law of physics" as restrictive.
You are free to believe whatever you want, but that doesn't mean others have to agree with you.
"Theories of physics" leaves everything open to question, which is what people on this forum are trying to do. Whether they succeed, time will tell.
If you want to change the known laws of physics, just provide data that can be reproduced. That is all that the scientific community asks. But if you DON'T provide data that can be reproduced, don't expect people to believe you.
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#19
by
Hobbes-22
on 22 May, 2023 14:07
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So that you know what camp I am in. There are no "laws of physics" only theories of physics.
A law of physics is a single equation that describes the behavior of one phenomenon. Newton's three laws of motion are an example. These laws are part of Newton's theory of mechanics, which describes the behavior of objects in motion.
Both are theory, in that we have a ton of evidence for both, but no way to ask the creator of our universe if these are really correct.
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#20
by
chazemz
on 22 May, 2023 15:08
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Well physics and "the creator" would make strange bed fellows. But you have used Newton who it is well know was very religious. It would be easy to rewrite third law as "you can maybe be Prometheus but you can never be a creator" Newton I believe wanted mv for kinetic energy since this fitted better with his beliefs.
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#21
by
laszlo
on 22 May, 2023 19:12
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Well physics and "the creator" would make strange bed fellows. But you have used Newton who it is well know was very religious. It would be easy to rewrite third law as "you can maybe be Prometheus but you can never be a creator" Newton I believe wanted mv for kinetic energy since this fitted better with his beliefs.
You have a source for that?
mv
2/2 (kinetic energy) is defined by integrating the work done to move the object over time. There is no theology involved.
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#22
by
laszlo
on 22 May, 2023 19:14
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The wind and fan in a closed space is simply a reformulation of the old pigeons flying in a cargo jet problem.
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#23
by
EspenU
on 22 May, 2023 19:38
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So that you know what camp I am in. There are no "laws of physics" only theories of physics.
Facts/laws are observations of how the world works, and theories are tested descriptions of how/why those facts/laws are the way they are.
They are different things. And a theory in physics is not the same as a theory in everyday language.
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#24
by
chazemz
on 22 May, 2023 19:50
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At the same time as Newton, Leibniz thought kinetic energy was mv² which was a more scientific estimation given the experimental evidence. Later it was a woman that came up with the correct formula.
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#25
by
Robotbeat
on 22 May, 2023 20:28
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Which woman?
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#26
by
laszlo
on 22 May, 2023 23:37
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Émilie Du Châtelet
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#27
by
zubenelgenubi
on 23 May, 2023 22:18
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Thread locked. 🔒
chasemz, this forum is built on civil discourse, and your posts digressed further and further from civil discourse.
The original post is a mechanical physics question, not a spaceflight question. This is a spaceflight forum, not a physics forum.
