Talk:Atomizer nozzle
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I don't know who is watching this article, but the explanation is incorrect. I'm surprised this hasn't caught up to the correct understanding of Bernoulli. I just watched the Don Herbert, Mr Wizard video making the same mistake (one of his few mistakes)
and thought I'd check here.
It is, sadly, an all too common and too often repeated misunderstanding of Bernoulli that the sped up stream of air creates a pressure lower than the air around it. Instead of:
- "When a gas is injected under pressure through a tube with a decreasing section, it speeds up, generating a pressure drop at the narrowest point (due to Bernoulli's principle)."
I recommend the following wording:
- "When a fast gas stream is injected into the atmosphere and across the top of the vertical tube, it is forced to follow a curved path up, over and downward on the other side of the tube. This curved path creates a lower presssure on the inside of the curve at the top of the tube. This curve-caused lower pressure near the tube and the atmospheric pressure further up is the net force causing the curved, velocity-changed path (radial acceleration) shown by Bernoulli."
This could be simplified to:
- "When the fast gas stream flows across the top of the tube it follows a curved path up and over the tube. It is this curved path that creates a lower presssure on the inside of the curve at the top of the tube. The curved path is a change in velocity (acceleration) shown by Bernoulli caused by the pressure difference"
Then instead of:
- The reduced pressure, due to the pressure difference between the two points, sucks up a liquid from a reservoir through a narrow tube into the moving gas flow, and projects it forward as a fine spray of droplets (although not atoms as the name suggests).
Which "two points" is not clear.
I recommend:
- "The difference between the reduced pressure at the the top of the tube and the higher atmospheric pressure inside the bottle pushes the liquid from the reservoir up the tube and into the moving stream of air where it is broken up into small droplets and carried away with the stream of air."
For the pressures of a curved path I reference Dr Holger Babinsky, Cambridge University Engineering Department
- His missing slides HERE (Click the Download Icon for the complete set of slides):
- This is the 2003 article he mentions in the video:
For the atomizer effect specifically , I Reference Weltner (I don't do this enough to know how to add a proper reference)
- Weltner in PDF - "Misinterpretations of Bernoulli's Law":
- Weltner as a web page:
Regards -- Steve -- (talk) 04:18, 4 January 2015 (UTC) . 》I too, am unsure of who might be watching this article. I also am surprised at the length of time an incorrect explanation has gone uncorrected. There is no direction component to Bernoulli's equation, i.e. there is no "curved path" requirement. While the referenced video goes to great lengths to demonstrate why lift from an airfoil is not sufficiently explained by Bernoulli's equation alone, it also clearly shows with the manometer demonstration that Bernoulli's equation does yield different pressures without any curve...and would clearly suffice for an atomizer. Bernoulli's equation is simply conservation of energy and mass for fluid flow in a noncompressible regime. The edit and accompanying explanation though obviously well intentioned are misleading. A curve is not needed for an atomizer. The part of the explanation that depends on curved flow is superfluous and should be removed. ````BGriffin