Venturi and the urban legend
#31
Nordschleife Master
#32
Nordschleife Master
Venturi effect
Ok - I have to admit - I had no idea what "Venturi Effect" was; so for those who want to know ..here it is.
The Venturi effect is a jet effect; as with an (air) funnel, or a thumb on a garden hose, the velocity of the fluid increases as the cross sectional area decreases, with the static pressure correspondingly decreasing. According to the laws governing fluid dynamics, a fluid's velocity must increase as it passes through a constriction to satisfy the principle of continuity, while its pressure must decrease to satisfy the principle of conservation of mechanical energy. Thus any gain in kinetic energy a fluid may accrue due to its increased velocity through a constriction is negated by a drop in pressure. An equation for the drop in pressure due to the Venturi effect may be derived from a combination of Bernoulli's principle and the continuity equation.
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 de Laval nozzle. Increasing source temperature will also increase the local sonic velocity, thus allowing for increased mass flow rate.
Referring to the diagram to the right, using Bernoulli's equation in the special case of incompressible flows (such as the flow of water or other liquid, or low speed flow of gas), the theoretical pressure drop at the constriction is given by:
where is the density of the fluid, v1 is the (slower) fluid velocity where the pipe is wider, v2 is the (faster) fluid velocity where the pipe is narrower (as seen in the figure). This assumes the flowing fluid (or other substance) is not significantly compressible - even though pressure varies, the density is assumed to remain approximately constant.
http://en.wikipedia.org/wiki/Venturi_effect
The Venturi effect is a jet effect; as with an (air) funnel, or a thumb on a garden hose, the velocity of the fluid increases as the cross sectional area decreases, with the static pressure correspondingly decreasing. According to the laws governing fluid dynamics, a fluid's velocity must increase as it passes through a constriction to satisfy the principle of continuity, while its pressure must decrease to satisfy the principle of conservation of mechanical energy. Thus any gain in kinetic energy a fluid may accrue due to its increased velocity through a constriction is negated by a drop in pressure. An equation for the drop in pressure due to the Venturi effect may be derived from a combination of Bernoulli's principle and the continuity equation.
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 de Laval nozzle. Increasing source temperature will also increase the local sonic velocity, thus allowing for increased mass flow rate.
Referring to the diagram to the right, using Bernoulli's equation in the special case of incompressible flows (such as the flow of water or other liquid, or low speed flow of gas), the theoretical pressure drop at the constriction is given by:
where is the density of the fluid, v1 is the (slower) fluid velocity where the pipe is wider, v2 is the (faster) fluid velocity where the pipe is narrower (as seen in the figure). This assumes the flowing fluid (or other substance) is not significantly compressible - even though pressure varies, the density is assumed to remain approximately constant.
http://en.wikipedia.org/wiki/Venturi_effect
#33
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Maybe we can light a match to a quart of Amsoil and really fire this thread up.
#36
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#38
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but you left out the all important contact patch...gotta get it all to the ground ya know!
#39
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#40
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In spite of a sometimes irritating style, MK adds more than a bit of competitive color to the forum. I admit that I have to restrain myself a lot on the pseudo-physics, should restrain myself a lot more, but nonethelsss feel that there is sometimes a valid contribution.
A PC lesson too: Things posted here last forever. It may seem fun to pile on, or vent or whatever. Just don't post things about him now that you wouldn't have before. A temporary ban is just that, temporary. He has an available path to redemption with the IB gods. He also has the ability to read this forum, and these 'forever' posts, even while he suffers through his 'time-out'. Think "Golden Rule" my friends.
A PC lesson too: Things posted here last forever. It may seem fun to pile on, or vent or whatever. Just don't post things about him now that you wouldn't have before. A temporary ban is just that, temporary. He has an available path to redemption with the IB gods. He also has the ability to read this forum, and these 'forever' posts, even while he suffers through his 'time-out'. Think "Golden Rule" my friends.
#41
The Parts Whisperer
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In spite of a sometimes irritating style, MK adds more than a bit of competitive color to the forum. I admit that I have to restrain myself a lot on the pseudo-physics, should restrain myself a lot more, but nonethelsss feel that there is sometimes a valid contribution.
A PC lesson too: Things posted here last forever. It may seem fun to pile on, or vent or whatever. Just don't post things about him now that you wouldn't have before. A temporary ban is just that, temporary. He has an available path to redemption with the IB gods. He also has the ability to read this forum, and these 'forever' posts, even while he suffers through his 'time-out'. Think "Golden Rule" my friends.
A PC lesson too: Things posted here last forever. It may seem fun to pile on, or vent or whatever. Just don't post things about him now that you wouldn't have before. A temporary ban is just that, temporary. He has an available path to redemption with the IB gods. He also has the ability to read this forum, and these 'forever' posts, even while he suffers through his 'time-out'. Think "Golden Rule" my friends.
My post was really just in jest and I do think Kibort is a valuable addition to this forum.
#42
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I'd never thought that Mark Kibort would ever get banned...even for the short term.
I've never read anything he wrote where he attacked someone personally, by calling them names or using things totally unrelated to the discussion to "attack" someone personally.
His arguments always seem to be centered around facts. I'm going to have to go search for the thread that got him banned.
I personally hope he is back really soon...I'm only partially done with my "Kibort" software....which will soon be available to everyone. This software removes 80% of the words that Kibort writes...so that you can actually read his posts and not have your head hurt, when you get to the bottom.
I've never read anything he wrote where he attacked someone personally, by calling them names or using things totally unrelated to the discussion to "attack" someone personally.
His arguments always seem to be centered around facts. I'm going to have to go search for the thread that got him banned.
I personally hope he is back really soon...I'm only partially done with my "Kibort" software....which will soon be available to everyone. This software removes 80% of the words that Kibort writes...so that you can actually read his posts and not have your head hurt, when you get to the bottom.
#44
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Kibort's posts often bring up much valuable, useful, and accurate information.....even if only from those who oppose his viewpoint But clearly he has a big fanclub (even if he is the president) who admire his accomplishments, after all Rennlister's paid for his stroker short block ! Given the length of other such "vacations" on similar forums adjusted for the minor differences in class.....I predict he will return in 14 days. Which when you think about it for Kibort to not voice his opinions for two weeks will seem like an eternity to him.
#45
Rennlist Member
My knowledge of physics is limited to noticing that gravity requires I wear a belt. And yet I usually find MK's posts entertaining. When they get too technical or verbose I just skip to the next post.
I couldn't count the number of times I have witnessed him respond to a mean spirited post with equanimity and elan and have never known him to respond in kind when rudely baited.
He may not be your cup of tea but he is a class act.
My open admiration is in no way prompted by my waiting to see my name on his car as an engine contributor.
I couldn't count the number of times I have witnessed him respond to a mean spirited post with equanimity and elan and have never known him to respond in kind when rudely baited.
He may not be your cup of tea but he is a class act.
My open admiration is in no way prompted by my waiting to see my name on his car as an engine contributor.
Last edited by Charley B; 06-07-2011 at 05:57 PM.