Talk:Venturi effect

message: I removed the reference to flutes, as the simple venturi effect isn't (to my knowledge) the main effect in a flute.  If that offends anyone, please feel free to add it back in with more explanation. zowie 03:15, 22 September 2005 (UTC)

message: I think these two articles should be merged because they are both relatively short and both try to discuss how the principal and the device work.  It should be easy to cover both in sub-sections of a single article if there is need to differentiate. -- Bovineone 02:19, 8 May 2006 (UTC)
replies: text: I believe these are the same effect - I vote Merge.  Nimur 14:40, 3 June 2006 (UTC)
thread_title: Merge Venturi and Venturi effect

message: In the Experimental apparatus, Venturi Tubes it says
A venturi can also be used to mix a fluid with air. If a pump forces the fluid through a tube connected to a system consisting of a venturi to increase the water speed (the diameter decreases), a short piece of tube with a small hole in it, and last a venturi that decreases speed (so the pipe gets wider again), air will be sucked in through the small hole because of changes in pressure. At the end of the system, a mixture of fluid and air will appear.
and the general description of the effect it says
The Venturi effect is a special case of Bernoulli's principle, in the case of fluid or air flow through a tube or pipe with a constriction in it.
It seems to indicate the converse could happen too...? 
So if Air under pressure is forced through a venturi tube it will be able to suck a liquid in through a small hole producing aerated liquid. 
eg The Venturi effect is used when a coffee machine uses steam under pressure to draw up and froth milk.
202.138.204.101 01:44, 1 December 2006 (UTC)
thread_title:  An everyday example of the venturi effect mixing air and liquid. 

message: This page only explains what the Venturi effect is through a number of terms that are impossible to understand for a layman. These terms are linked to, but requiring people to read about those as well makes it harder to understand what this is all about.
Could someone please add a simple explanation of what this is about, too? Something like
"In Physics, the Venturi Effect refers to a situation where materials in gaseous or fluid form take on a lower pressure than those in the surrounding area. This happens because (...technical explanation...)"
I'm not sure whether this is accurate (which is why I didn't add it myself), but it would be tremendously helpful.
Another good example of this is demonstrated when you blow across the top of a straw and the drop in pressure pulls some of the liquid up the straw.
:Static ports on aircraft like a Cessna 182 are simply holes in the sides of the fuselage. Air flows across these holes at the same speed as the aircraft's air speed, yet the pressure at the static port is the same as ambient, regardless of the aircraft speed (within the range of a Cessna 182). I don't see how the straw situation is any different, unless you're not blowing directly perpendicular to the opening in the straw. Jeffareid (talk) 06:54, 17 March 2008 (UTC)
replies: text: That's because it's not. The static port measures the static pressure of the air, which is all the same unless some other mechanism converts some of the theoretical dynamic pressure (ie, "air flowing past") into a real static pressure, eg angling the opening forward. The explanation of venturis here seems to be so oversimplified as to be wrong. --Adx (talk) 06:22, 20 June 2010 (UTC)
replies: text:  No, I got this wrong, based on my errant ramblings on the Bernoulli principle talk page. Actually it sounds correct apart from the last sentence, but that's just luck. Now I understand: Flowing air itself doesn't "have" a lower pressure. A venturi does, because it forces the flow to constrict and expand within a solid pipe - the pressure gradients at each end mean the fast flowing section happens to have a lower pressure, just like an axial flow jet engine happens to have a higher pressure inside it. A static port measures the real (static) pressure with little error irrespective of the speed of gas flowing by. If the port is tilted, it begins to measure some of the imaginary (dynamic) pressure which is nothing more than a way to express the kinetic energy in the flow. --Adx (talk) 00:12, 21 June 2010 (UTC)
thread_title:  What? 

message: "A venturi can also be used to mix a fluid with air." - Do you mean "mix a liquid with a gas"?
Air is a fluid. You can read about this on a website called "Wikipedia".  —Preceding unsigned comment added by 99.231.124.188 (talk) 23:37, 23 February 2008 (UTC)
thread_title:  Um, air is a fluid. 

message: This is a tap water driven syphon for aquariums. Click on the link, then images, then go to page 3 to see diagram.
aquarium_syphon
It's not significantly different than the one patented in 1933. Click on image, and note figure 4.
washer_syphon
Is there a better name than syphon or siphon for these type of devices? 
I use the 1984 patented version for my aquarium, but recall an almost identical device I used
to drain a basement back in the mid 1960's.
I've tried to find a diagram for one of these outside of patents, but I've had no luck in finding one.
Jeffareid (talk) 01:40, 16 March 2008 (UTC)
thread_title:  An item that should be added to practical uses 

message: Besides high winds experienced among tall buildings,it should be noted that the effect Venturi defined has been applied quite deliberately for thousands of years in vernacular architectures, and is a core principle in contemporary passive energy design in architecture. For an architectural vision of the applied Venturi effect that may have cross disciplinary value, see Hassan Fathy's work online at the unu website, or google anything along the lines of passive solar, passive energy, solar chimney,or cooling towers. From a passive strategies perspective, the Venturi effect  appears as how Nature seeks equilibrium when a constant flow crosses a channel with a nonconstant shape,(a funnel or a constriction): there will be compensations in changes in velocity and therefore pressure. I also see applied in  (Fathys descriptions)the strategy of simply connecting extremes (hot to cold, or high pressure to low pressure, or high velocity to low velocity)  to force accelerated airflow to then capture in evaporative mechanisms. Someone verify please, but I really think, to aid in definition, just this alone does not involve the  Venturi Effect when there isnt an actual constriction in the channel: that is just a more general harnessing of the principle of equistasis. In traditional passive designs, there usually is a constriction added (one side has larger openings than the other,or a flume or chimney is built) and when that dissimilarity in opening sizes occur, it is said that the Venturi effect is amplifying the system. In that, then, it appears the Venturi Effect is the effect of a physical funnel.Sparrow7 (talk) 09:21, 14 June 2008 (UTC)
thread_title:  Passive solar design applications of the Venturi effect 

message: Some extracts:
Before 26th January 2009:
The limiting case of the Venturi effect is choked flow, in which a constriction in a pipe or channel limits the mass flow rate through the channel, because the local pressure in the constriction cannot drop below the vapour pressure in a liquid. Limiting ventury effect is also associated with choked flow of compressible fluid through a convergent-divergent nozzle. Here the choked flow is a limiting venturi condition which occurs when the mass flow rate will not increase with a further decrease in the downstream pressure environment.
From 26th January 2009 (Version by Cousin Merle):
The limiting case of the Venturi effect is when a fluid reaches the state of choked flow, where the fluid velocity approaches the local speed of sound.  In choked flow the mass flow rate will not increase with a further decrease in the downstream pressure environment.
However, mass flow rate for a compressible fluid can increase with increased upstream pressure, which will increase the density of the fluid through the constriction (though the velocity will remain constant).  This is the principle of operation of a convergent-divergent nozzle.
It looks to me as though the later version is better in some ways but leaves out something that looks likely to be correct and important.
Man with two legs (talk) 13:44, 26 January 2009 (UTC)
replies: text: Hi Man.  Your version is a significant improvement.  The original comment about cannot drop below the vapour pressure in a liquid is nonsense.  Choking occurs with gases as well as liquids.  I suggest you delete the word environment from the expression downstream pressure environment.  It is the pressure that is relevant.  Dolphin51 (talk) 22:29, 26 January 2009 (UTC)
replies: text: Actually, they are not my edits.  But I am not at all clear that cannot drop below the vapour pressure in a liquid is nonsense.  In a gas, the corresponding limit would presumably be vacuum.  It seems plausible to me that the speed of sound is not the only thing limiting flow. Man with two legs (talk) 13:18, 27 January 2009 (UTC)
thread_title:  Choked flow 

message: Hi I've been struggling to find a formula to compute the air mass flow through the throat of a closed outlet venturi tube. What I have is a reciprocating single cylinder air compressor that has a venturi tube at it's outlet with the outlet of the venturi tube flowing into a closed tube with a constant volume. Overall I'd like to achieve a plot of the mass air flow through the throat area of the venturi with respect to crank angle of one cycle of the compressor. The beginning pressure throughout everything would be atmospheric. 
Thanks for your time & any replies or suggestions is appreciated,
-nick  —Preceding unsigned comment added by Nar456 (talk • contribs) 04:08, 3 February 2009 (UTC)
thread_title:  Venturi formula? (closed outlet) 

message: the article doesn't mention why it is called the Venturi effect.  —Preceding unsigned comment added by Fintim (talk • contribs) 13:57, 9 October 2009 (UTC)
thread_title:  Why is it called the 'Venturi' effect 

message: Air flows over the top of an aircraft wing. The stable air around the plane and the foil above the cord line of the wing create a venturi around the wind going directly over the wing. Hence creating a low preasure on top of the wing lifting it upward.
This is not a good example of venturi effect. From this Nasa article: a wing section isn't really half a Venturi nozzle. nasa_airplane_bernnew.html Jeffareid (talk) 01:28, 28 March 2010 (UTC)
replies: text: I agree with Jeff.  In fact, a lot of the so-called examples of venturi effect listed in this article are not really examples at all, or at least not good examples.  I recommend a thorough review of all the current examples to remove those that don't belong here.  Is there any opposition to such a review? Dolphin51 (talk) 07:03, 28 March 2010 (UTC)
replies: text: I agree with Dolphin51's proposal to review the article to weed out unwanted "examples" of venturi effect. Salih (talk) 07:22, 28 March 2010 (UTC)
replies: text: The wing reference is now removed. I leave it to the experts here to remove the other invalid examples. Jeffareid (talk) 10:13, 29 March 2010 (UTC)
replies: text: The article still contains this statement implying that Ventri/Bernoulli is related to wing behaviour: ″The Bernoulli Principle and its corollary, the Venturi effect, are essential to aerodynamic as well as hydrodynamic design concepts. Airfoil and hydrofoil designs to lift and steer air and water vessels (airplanes, ships and submarines) are derived from applications of the Bernoulli Principle and the Venturi effect″ - Per the above discussion, I think this should be removed. Infact, I think the entire block of text at the bottom of examples should go - it doesn't belong in examples, and the rest of the article has all the explanation necessary already. Please let me know if there are any concerns or objections.SteveSmith98 (talk) 13:13, 3 March 2018 (UTC)
thread_title:  Examples - Air flows over the top of an aircraft wing. 

message: The inclusion of 'or a thumb on a garden hose' in the opening sentence is not correct. In the case of a hosepipe the water is exiting to atmosphere. Putting a thumb over the end of a hose simply restricts the flow rate and a slowed flow rate causes reduced pressure losses by means of friction along the hose. A thumb over a hose is increasing the pressure of the water arriving at the end of the hose and thus the exit velocity goes up thanks to the pressure. The water does not speed up due to it having to pass the restriction of the thumb and then fill the hose beyond as it would with a squashed portion of hose part way along. --Narrowneck (talk) 20:11, 21 November 2011 (UTC)
replies: text: I agree so I removed the offending words.  See my diff. Dolphin (t) 02:14, 22 November 2011 (UTC)
thread_title: Thumb over hose is not a correct example and is misleading - I think

message: What happens if you blow backwards through this apparatus?
Will the higher flow side still have less pressure? 
  — Preceding unsigned comment added by 64.146.180.237 (talk) 04:22, 5 February 2013 (UTC)
thread_title:  what happens if you blow backwards through a venturi meter, 

message: I wonder about the applicability of Bernoulli's equation to this problem: The argumentation is that the static pressure in the region with the fast flow is reduced and therefore the water in a measuring tube rises to a lower value. 
However, in the measuring tube v=0. So if Bernoulli's equation was valid, the full static pressure should be recovered. 
So why is only the static pressure transmitted into the tube (and Bernoulli's equation not valid)? --46.128.146.13 (talk) 20:05, 8 March 2015 (UTC)
replies: text: The flow is not through the measuring tube, so there is no reason to apply Bernoulli's principle there. The measuring tube at the constriction is measuring the pressure in the fluid flowing through the constriction. That flow is faster, so the pressure at that point is less, which is demonstrated by the lower fluid level in the measuring tube. Apuldram (talk) 16:42, 12 August 2017 (UTC)
thread_title:  Applicability of Bernoulli's equation in the measuring tube 

message: I tried to find out where the Clarinet claim comes from ("The barrel of the modern-day clarinet, which uses a reverse taper to speed the air down the tube, enabling better tone, response and intonation"), and found this. Seems like the list of applications on Wikipedia was copied word-for-word from that book, or the other way around. However, I couldn't find any other source talking about it. All I could find was this article which claimed that the effect is used for the clarinet tone holes, not for the tube itself. Esn (talk) 08:35, 2 January 2017 (UTC)
thread_title: Clarinet?

message: In the equation stating the pressure differential between V1 and V2 are both those units squared within the equation? That is how it would appear from the way it's written ... or am I simply missing something. Thank you. 
Tapalmer99 (talk) 12:51, 13 May 2018 (UTC)
thread_title:  Explanation/definition of equation 

message: Following the flow equations under [orifice plate] add "v" subscript to show Qv as volume flow.
Then recommend adding an equation for mass flow Qm with subscript m.
https://en.wikipedia.org/wiki/Orifice_plate#Expansibility_factor
DLH (talk) 20:35, 6 November 2019 (UTC)
thread_title:  Add Mass flow and subscripts v and m 

message: Should Venturi be capitalised?   How far should we take this?  COMMONNAME never capitalises it, in describing the device. Should "Venturi Effect" be capitalised?  As a proper name, or as a phrase (i.e. one or two words capitalised?) Andy Dingley (talk) 17:01, 3 December 2019 (UTC)
thread_title:  Capitalisation? 

message: I'd be interested in reading a list of devices relying on fluid dynamics such as the Venturi tube. Are there enough things to generate such a category page?  — Preceding unsigned comment added by NomadicVoxel (talk • contribs) 22:59, 23 March 2021 (UTC)
thread_title:  Is there a category for devices like the Venturi tube?