Talk:Choked flow

message: I just finished the complete revision of this article. - mbeychok 21:39, 18 March 2006 (UTC)
thread_title: Finished a complete revision

message: If you agree that choked flow is that resulting from given upstream conditions to the point where downstream backpressue will not effect flow then you might want to rearrange article to different types of choked flow not necessarily in the following order:
1- choking due to the area change--ie venturi effect
2. adiabatic choking in pipes
3 isothermal choking
4-choking with heat addition to pipe
You have started with perfect gas using a Cd.  Perhaps a real gas formulation such as a "Generalized" Beattie-Bridgeman or others could be included.  By Generalized, I am refering to type of equation of state (EOS)which is reasonably accurate for a number of gases.
The EOS could also be applied to items 2, 3 and 4 above. 
Give one example for each discussion.
Main focus for all of above would be for a non-condensing gas.
Regards
Sailoday28 22:45, 23 February 2007 (UTC)
thread_title:  Purpose of "choked" flow 

message: Currently this article uses Q to denote mass flow rate. Usually m(dot) is used for mass flow rate, and Q is used for volumetric flow rate. For example, refer to the wiki page on Orifice Plates. Can I suggest changing the nomenclature in this article, to be consistent and to avoid confusion? Logicman1966 (talk) 03:01, 15 October 2008 (UTC)
replies: text: I reluctantly agree. The symbol used in the article on mass flow rate is m(dot). Unhappily, the m(dot) symbol is:
# Cryptic to those unfamiliar with the use of the notation in calculus, and
# Not available as a single glyph in the English alphabet. - Ac44ck (talk) 03:29, 15 October 2008 (UTC)
replies: text:  OK, as there were no objections to my suggestion, I have changed Q to m(dot); It only appears 3 times in the article. I am happy that now there is consistency with other pages. Logicman1966 (talk) 11:39, 16 October 2008 (UTC)
thread_title:  A suggestion on nomenclature 

message: The mass flow rate caluclation seems to have the wrong units under the square root sign.
The units would need to be kg-sq per second-sq.  They are not.  —Preceding unsigned comment added by 206.190.70.135 (talk) 19:41, 2 March 2010 (UTC)
replies: text: Which calculation? There is more than one. What units do you think it has under the square root sign? -Ac44ck (talk) 03:45, 13 October 2010 (UTC)
thread_title:  Wrong units? 

message: 159.245.32.2 (talk) 19:34, 18 May 2011 (UTC)
thread_title: Is there an equation to calculate choked flow of a liquid??

message: So far, the objections I have heard don't hold a lot of water:
# One calculation was off by 15%. Were there no mistakes made? Was the "right" value for compressibilty used? How close is "close enough?"
# The equation was derived for ideal gases. And the compressibility factor was introduced to make some (not perfect) allowance for the behavior of real gasses. What is wrong with that?
Then, the denunciation of a practical-for-some-purposes formula and the proposed alternative are unsourced. - Ac44ck (talk) 03:20, 1 June 2011 (UTC)
thread_title:  Recent deletion of formula for 'real gas' 

message: I can read:
At choked flow the mass flow rate can be increased by increasing the upstream pressure, or by decreasing the upstream temperature.
I think the first part of this statement is true, but the second is false.
?  — Preceding unsigned comment added by CharlesCo (talk • contribs) 18:10, 12 October 2011 (UTC)
thread_title:  Error? 

message: A recent edit removed the centering of numbers in a table. Now the numbers are left-justified in the cell. Why is this better? The WP:MOS seems to be silent on this issue. - Ac44ck (talk) 02:44, 11 October 2012 (UTC)
thread_title:  Centering numbers in a table 

message: I would like an explanation on top of the facts. Why does the speed not increase (much)? I suspect it is because the gas laws for v>1M and those for v<1M are different. In one area it favors a change in speed and in the other a change in density? Somehow in the narrowing it can not meet both behaviors in a continues way? --77.1.163.208 (talk) 09:54, 5 February 2013 (UTC)
thread_title:  An explanation would be nice 

message: There may be an error in the calculation of the specific heat formula:
[2/(1+k)]^[k/(k-1)]
When I calculate the formula with dry air (k = 1.4), I get a value of about 0.5, not somewhere between 1.7 and 2.1 or so.  Please check my math and comment. 
Scirocco84 (talk) 19:27, 1 March 2013 (UTC)
thread_title:  Error in Specific Heat Ratio Formula 

message: This comment was in the led of the article. It belongs on the talk page:
:The formula shown below appears to be incorrect; choked flow in other references is linearly proportional to pressure; for example see J. M. Lafferty (ed.), Foundations of Vacuum Science and Technology, Wiley, 1998 p. 116; and J. J. Sullivan et al, Mass flow measurement and control of low vapor pressure sources, J. Vac. Sci. Technol. A7, p. 2387 (1989)
- Ac44ck (talk) 17:27, 9 March 2013 (UTC)
thread_title:  Comment moved from led 

message: Hi all. Critical flow used to direct to this page. It doesn't any more. I've switched the link back to refer to Froude numbers, on the basis that:
* That definition is definitely right;
* A previously copyvio'd article initiation at Critical flow definitely referred to the Froude meaning;
* This page makes no mention of Froude numbers, nor does it ever use the phrase "Critical flow".
If anyone here thinks I've been too bold, please set up a disambiguation at Critical flow, not just a redirect, so we can have both meanings. And please also make it clear that this page is about a technical use of the phrase too! If someone drops me a note at my talkpage, I'm happy to provide the Froude number contextual info for the redirect. Thanks. DanHobley (talk) 04:49, 6 August 2013 (UTC)
thread_title: Critical flow

message: In the section that starts:
Choking in change of cross section flow[edit]
Assuming ideal gas behaviour, steady-state choked flow occurs when the ratio of the downstream pressure p_0 falls below a critical value p^{*}.
I believe that p_0 should be deleted.  It seems to say the downstream pressure is p_0, but this is actually the upstream pressure, right?  — Preceding unsigned comment added by 207.121.73.2 (talk) 15:18, 24 March 2014 (UTC)
replies: text: I think it was confusing by virtue of trying to say too many things at the same time. I eliminated some words to simplify it. - Ac44ck (talk) 03:32, 25 March 2014 (UTC)
thread_title:  Possible error 

message: Original text:
For air with a heat capacity ratio k = 1.4, then p^{*} = 0.528 p_0; other gases have k in the range 1.09 (e.g. butane) to 1.67 (monatomic gases), so the critical pressure ratio varies in the range 0.487 < p^{*}/p_0 < 0.587, which means that, depending on the gas, choked flow usually occurs when the downstream absolute pressure drops to below 0.487 to 0.587 times the absolute pressure in stagnant upstream source vessel.
I changed "downstream absolute pressure" to "downstream static pressure", because in a losless flow the absolute pressure should stay the same.
92.198.27.167 (talk) 08:57, 9 May 2014 (UTC)
thread_title:  Absolute vs. static pressure 

message: Sonic velocity is always understanded as the sound velocity  in air or gas stream. 
The sonic velocity in the context of choked flow is the velocity of gas where excess energy started to be converted to sound. Such as gas flow trough a small long pipe with high pressure at upstream discharging to atmospheric pressure. At sonic velocity at discharge end, the pressure drop of the pipe is lower than the pressure differential between two ends of the pipe. The excess pressure is then converted to vibration and sound.  — Preceding unsigned comment added by 158.35.225.229 (talk) 12:17, 20 May 2014 (UTC)
thread_title:  Sonic velocity 

message: they are used in offshore platforms...  — Preceding unsigned comment added by 182.74.166.18 (talk) 11:39, 17 December 2014 (UTC)
thread_title: re: ??

message: "In the case of upstream air pressure at atmospheric pressure and vacuum conditions downstream of an orifice, both the air velocity and the mass flow rate becomes choked or limited when sonic velocity is reached through the orifice."
-This section is unclear in both significance and fundamental understanding for someone trying to learn from the article.  Is there something significant about the upstream pressure being at atmospheric condition? Will higher upstream pressure do the same thing? Furthermore, an explanation of how and why both air velocity and mass flow rate becomes choked or limited at sonic velocity is warranted.  Finally, "the air velocity" seems to imply this section is only referring to air and not generic gas choking, like the rest of the article.
Sjkcarnahan (talk) 16:09, 31 March 2017 (UTC)
thread_title:  Vacuum Conditions 

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thread_title:  External links modified 

message: I suggest to insert the mathematical definition of the sonic velocity, which is the partial derivative of the pressure with respect to the density, at constant entropy conditions. PeacEng (talk) 17:52, 2 April 2024 (UTC)
thread_title:  Sonic velocity - mathematical definition