load loss

[Ing Italy]

Good evening,

have you ever had to deal with unidirectional shrinkage of a fluid? .for example a flowing fluid meets a section that gradually or abruptly is reduced in one direction, width or height... ? .
If you have already dealt with this type of accidentality, can you direct me to a value of the loss coefficient you consider reliable or a web resource that allows me to have such data? .

Thank you.

 

[PierArg]

Hi ingitaly,
I don't know if I understand your question. try to consult the annex

pcfarina.eng.unipr.it/dispense99/patini119156.doc

p.s: open the browser and paste the address, should open a word file

 

[meccanicamg]

I attach the values of the coefficients of the load losses of the rectangular tubes that shrink or expand are in a dimension.

the formula that governs is as follows:
y = c0*0.5*ro*v0^2 where

y = concentrated load losses [Pa]c0 = adimensional coefficient related to the output section
v0 = output section speed [m/s]ro = fluid density [kg/m^3]if you want to use the input section you will have the following conversion:
ci = c0*v0^2/vi^2 where

vi = speed referring to the input section [m/s]pay attention to the ratio of areas to understand whether it is a divergent or a concentrate and choose the correct value of c0.

If you need anything else there are in some libraries the manuals of the ashrae to be able to consult or write to the American society and get some excerpts of the regulations.
other information for aeraulic plants can be found on the technical manual of the cbi (fluid, acoustics of the fans, load losses) if still available in pdf somewhere written by john spreafico - free publication - 1st edition).
more you can find it on the caleffi website in the technical notebooks.

 

[Ing Italy]

Hi ingitaly,
I don't know if I understand your question. try to consult the annex

pcfarina.eng.unipr.it/dispense99/patini119156.doc

p.s: open the browser and paste the address, should open a word file

hi pierarg..thanks for the link!.
what I meant was a section reduction in one dimension, for example a rectangular section that sees only the height but not the width or only the width but not the height.

"I know" flour for a while but never gave me great satisfaction in terms of numerical values. I saved that document a little while ago because it never hurts, good Sunday!

 

[Ing Italy]

I attach the values of the coefficients of the load losses of the rectangular tubes that shrink or expand are in a dimension.

the formula that governs is as follows:
y = c0*0.5*ro*v0^2 where

y = concentrated load losses [Pa]c0 = adimensional coefficient related to the output section
v0 = output section speed [m/s]ro = fluid density [kg/m^3]if you want to use the input section you will have the following conversion:
ci = c0*v0^2/vi^2 where

vi = speed referring to the input section [m/s]pay attention to the ratio of areas to understand whether it is a divergent or a concentrate and choose the correct value of c0.

If you need anything else there are in some libraries the manuals of the ashrae to be able to consult or write to the American society and get some excerpts of the regulations.
other information for aeraulic plants can be found on the technical manual of the cbi (fluid, acoustics of the fans, load losses) if still available in pdf somewhere written by john spreafico - free publication - 1st edition).
more you can find it on the caleffi website in the technical notebooks.

Hello mechanicalmg!

interesting your link; As for a single-dimensional enlargement I also have something but unfortunately I never managed to find anything on a monodirectional shrinkage.
the formulations you refer to a monodirectional enlargement though? .In the images is only the case.

I believe that then I will reason on the gradual monodirectional enlargement to have a reference limit value, then, knowing that narrowing causes less energy losses of an enlargement I will exploit the typical trends of enlargements and two-dimensional narrowings of section to understand in principle how to scale the value of a monodirectional enlargement to the case of monodirectional shrinkage.

I also know the caleffi catalogue well, which often has English-American bibliography and in fact ashrae is a good reference, I will see if I can get something.
Thank you so much!!

 

[Ing Italy]

I define you more exactly the type of accidentality: This is a constant band curve and variable shape.

 

[PierArg]

I honestly don't know if your question is easily available in literature or not.
I've never seen anything like that before.

:

 

[Ing Italy]

Hi.

I think I can easily find it because I have already consulted almost all the English/American literature that I have managed to find on the internet...another card I could play is to contact some company that builds pipes and air ducts and see if they give me some idea of maximum.. . Otherwise I proceed with my reasoning that I think it's the best I can do right now.
Thank you, pier!

 

[meccanicamg]

the values I posted before you are both x enlargement and shrinking. Just look at the relationships between areas if greater or less than one. are ashrae boards, American regulatory body of the fluid sector etc.

Don't be fooled by the box.

 

[Ing Italy]

I traveled both ways: first my associative reasoning reporting trends and bonds between load losses for bidirectional accidentality to the unidirectional case starting from the worst case as an accidentality up to the one I wanted... then I used the table of mechanics...the results are quite similar and...the satisfaction really so much.
hello and thanks to both

 

[meccanicamg]

I traveled both ways: first my associative reasoning reporting trends and bonds between load losses for bidirectional accidentality to the unidirectional case starting from the worst case as an accidentality up to the one I wanted... then I used the table of mechanics...the results are quite similar and...the satisfaction really so much.
hello and thanks to both

lessmal than mental grievances have given good results, however the tables that I have placed at international level, otherwise it is necessary to experiment with blower and steel tube ...the classic laboratory machine and insert our particularity and tabulate pressures