Air Nozzle Question, should be easy?
Air Nozzle Question, should be easy?
(OP)
Hello
I am self-learning the DeLaval nozzle, or Convergent-Divergent nozzle, and have read much from many different sources.
Have one question about the C-D nozzle with air.
The standard math shows choking at Mach 1, and the math derivations describe this. In my readings, I have found a single reference that does not agree with the standard formulas, taking into consideration real gas effects. This fellow, Abramov, is saying that considering air as a real gas, the throat critical flow is not M=1, but is instead much lower at M=0.5345 for air. His conclusion is that the effect of increasing velocity at the diverging section can be achieved with all velocities less than M=1 in the pipe, thereby avoiding Mach waves and shock. This seems odd to me.
QUESTION: Is this a legitimate statement, or is this false? If false, can you point to the falsity?
This is an interesting question because I can see two possible answers, and both contain amazing implications.
1. Abramov is correct that in practice, the DeLaval effect can occur at M=0.5345 at throat, which implies all other reference materials and texts are erroneously assuming ideal gas behavior for air in a simple C-D nozzle. For this case, it leads to many energy-efficient applications of devices that could avoid shock entropy generation.
2. Abramov is not correct. He has generated a steady stream of patent applications and some granted patents over the last decade, all of which are based on this core idea of when the Delaval effect occurs. I doubt he has made a mistake, which then leads to the possibility of a complicated, long-term Scam or ruse. Equally amazing possibility here.
Abramov does supply a derivation of his math, and I can see the algebra is correct there, but is there some error buried within this derivation that you can identify? Possibly the very first step of his math contains an assumption that is wrong? If Abramov's documents are part of a Scam, it should be possible to reveal that via his math derivation steps, but my ability level is not high enough to see if there is an error buried there, especially if the error was purposely buried.
Attached is an edited pdf excerpt from his original lengthy document. Equations 6.1 to 6.9 show his derivation.
Abramov also states that "in practice" the DeLaval effect is seen at M<1. If a person has hands-on experience with C-D nozzles, then this is another path that could be used to reveal if Abramov is telling the truth or not.
Any help would be much appreciated. I hope that you see this as an interesting problem. Of course, I can send you any additional material, if needed.
Thanks again for your time,
I am self-learning the DeLaval nozzle, or Convergent-Divergent nozzle, and have read much from many different sources.
Have one question about the C-D nozzle with air.
The standard math shows choking at Mach 1, and the math derivations describe this. In my readings, I have found a single reference that does not agree with the standard formulas, taking into consideration real gas effects. This fellow, Abramov, is saying that considering air as a real gas, the throat critical flow is not M=1, but is instead much lower at M=0.5345 for air. His conclusion is that the effect of increasing velocity at the diverging section can be achieved with all velocities less than M=1 in the pipe, thereby avoiding Mach waves and shock. This seems odd to me.
QUESTION: Is this a legitimate statement, or is this false? If false, can you point to the falsity?
This is an interesting question because I can see two possible answers, and both contain amazing implications.
1. Abramov is correct that in practice, the DeLaval effect can occur at M=0.5345 at throat, which implies all other reference materials and texts are erroneously assuming ideal gas behavior for air in a simple C-D nozzle. For this case, it leads to many energy-efficient applications of devices that could avoid shock entropy generation.
2. Abramov is not correct. He has generated a steady stream of patent applications and some granted patents over the last decade, all of which are based on this core idea of when the Delaval effect occurs. I doubt he has made a mistake, which then leads to the possibility of a complicated, long-term Scam or ruse. Equally amazing possibility here.
Abramov does supply a derivation of his math, and I can see the algebra is correct there, but is there some error buried within this derivation that you can identify? Possibly the very first step of his math contains an assumption that is wrong? If Abramov's documents are part of a Scam, it should be possible to reveal that via his math derivation steps, but my ability level is not high enough to see if there is an error buried there, especially if the error was purposely buried.
Attached is an edited pdf excerpt from his original lengthy document. Equations 6.1 to 6.9 show his derivation.
Abramov also states that "in practice" the DeLaval effect is seen at M<1. If a person has hands-on experience with C-D nozzles, then this is another path that could be used to reveal if Abramov is telling the truth or not.
Any help would be much appreciated. I hope that you see this as an interesting problem. Of course, I can send you any additional material, if needed.
Thanks again for your time,
RE: Air Nozzle Question, should be easy?
Good Luck,
Latexman
RE: Air Nozzle Question, should be easy?
If you want to see the raw data of all his writings, best site is ESPACENET, search on Yuri Abramov. Here, can download pdfs, and can also view the correspondence between patent offices and him, for each of the files.
After reading his raw data, you will be appreciative of my condensed version pdf attached to original post!
I am still hoping that a forum reader will be able to provide some assistance with the math derivations; both the classic method and Abramov's seem equally correct to my level of understanding, and that is the mystery.
RE: Air Nozzle Question, should be easy?
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Air Nozzle Question, should be easy?
Either way you look at it, Abramov is a master in his field; that field being compressible flow theory, or that field being able to weave a very complex, multilevel scam!
He submits patent applications every year or so, with different titles, but the description content is mostly cut and paste identical between all of them. This could point to an attempt to claim "patent pending" since some of the applications are always in process at any given time. But that is just conjecture, his math derivation is where the proof will be found.
RE: Air Nozzle Question, should be easy?
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Air Nozzle Question, should be easy?
RE: Air Nozzle Question, should be easy?
Consider the document attached .You may want to contact those experts to support your query .
Good luck
Pierre
RE: Air Nozzle Question, should be easy?
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Air Nozzle Question, should be easy?
RE: Air Nozzle Question, should be easy?
Of concern is his continual referencing Feynman's Lectures on Physics, which is the text I had in college, but that was more than 40 years ago, so for a patent awarded in 2018, it's an oddly anachronistic reference.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Air Nozzle Question, should be easy?
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Air Nozzle Question, should be easy?
https://www.freepatentsonline.com/result.html?sort...
I'm SHOCKED!!! He actually has a 9-page patent award: https://www.freepatentsonline.com/7313287.html Although, not sure why he got that awarded; we studied hexagon pixel arrays in a class in college, 43 years ago. That was pick-breaker; turned out it wasn't possible to come up with a closed form solution for the 2D Fourier transform for the image
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Air Nozzle Question, should be easy?
RE: Air Nozzle Question, should be easy?
RE: Air Nozzle Question, should be easy?
It does seem like sloppy math/physics. 44.64 is the number of moles in a "cube" meter, but its mass is only 1.225 kg. Other sloppiness is that certain values are at STD, which are not the conditions he's citing.
TLDR, so I'm not going to chase that rabbit at 107 pages for the entire document
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Air Nozzle Question, should be easy?
He shows input energy being only CvT, but then shows output energy as only mRT (with incorrect units). This is BOGUS. He is conveniently ignoring that all three of Pressure, Volume, and Temperature will change together.
I know his text is TLDR, but he did lure me into reading thoroughly. His text contains majority of correct information, but the conclusion is where he pitches the curve ball. Like most con games, it is based on fact but skewed when it progresses forward.
Of course, I could be wrong on that, which is why I posted in the first place to see if any forum readers might have some specific insight. The comments have helped me immensely to collect thoughts on this. A valuable learning experience. Thank You for the thoughtful comments.
RE: Air Nozzle Question, should be easy?
To you and others
A serie of videos about compressible flow is available on Youtube :
https://www.youtube.com/watch?v=ewoUwCVa3QY
The lecturer Prof john R.Biddle may want to support your query: jrbiddle@cpp.edu
The videos cover incompressible and compressible flow (34 videos).
Good luck
Pierre
RE: Air Nozzle Question, should be easy?
That video is EXACTLY what I am seeking. I will study closely to gain some footing, and then will reach out to Prof Biddle if and when I get stuck.
Very good video, it matches exactly what I was trying to explain in above posts,
THANK YOU IMMENSELY, right on target. The derivation is the true method to de-bunk Abramov, who knows? Need real proof to be assured.
RLund
RE: Air Nozzle Question, should be easy?
The text book to support the videos is the following :
Frank White, Fluid Mechanics, 5th ed., McGraw-Hill, 2016
note : More recent editions are available .
Pierre
RE: Air Nozzle Question, should be easy?
Update is welcome !
Pierre