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2

Negative Resistance Coeffecient For Tees


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#1 panagiotis

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Posted 11 May 2024 - 12:00 AM

Hello everyone,

I was reading somewhere that the K value (resistance coeffecient) for tees can be negative. What is the reasin for that?

#2 breizh

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Posted 11 May 2024 - 03:01 AM

Hi,
weird, share the references.
Breizh

#3 panagiotis

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Posted 11 May 2024 - 04:12 AM

Hi Breizh,

It is weird? I cannot find the reference anymore!
That's why I am asking in case someone is aware of it.

Maybe the interpretation of negative is that
it goes to higher energy.

#4 latexman

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Posted 11 May 2024 - 06:02 AM

It is so in my 2018 version of Crane Technical Paper No. 410.

 

Energy is added to the slower moving fluid accelerating to the velocity of the total combined flow.



#5 panagiotis

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Posted 12 May 2024 - 02:46 AM

Hi Latexman,

I will check the Crane for more infos!

You are referring to the case of mixing, right?

#6 latexman

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Posted 12 May 2024 - 04:58 AM

Negative K value is a larger effect when both flows converge, but IIRC it is present to a lesser degree in one of the two diverging cases too. See Crane TP # 410.

#7 breizh

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Posted 12 May 2024 - 05:38 AM

consider this link,
https://www.google.c...ZDSwL4dPFLpgHFm

 

Note : Get a copy of "pipe flow a practical and comprehensive guide " by Rennels and Hudson for full explanation. 

 

Breizh



#8 fallah

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Posted 12 May 2024 - 11:13 AM

Hello everyone,

I was reading somewhere that the K value (resistance coeffecient) for tees can be negative. What is the reasin for that?

 

Hi,

 

The key point is pressure loss coefficients in tees are more impacted by flow distribution than velocity and diameter.

Then mixing flows in tees could result in negative pressure loss coefficients, which is due to a negative pressure created by the momentum of the large inlet flow.



#9 panagiotis

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Posted 13 May 2024 - 11:53 PM

Hello everyone,

Thank you for your explanations!




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