Static fluid hammer analysis: Branches

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r2user
Beiträge: 144
Registriert: Mi 14. Sep 2011, 10:18

Static fluid hammer analysis: Branches

Beitrag von r2user »

I have a query regarding calculation of steam hammer forces.
In my system I have calculated the force using the Rohr2 function "Calculate fluid hammer loads".
Data used is:
Closing time : 125mSec
Mass flow : 34Kg/sec
Sound Speed : 650m/s.

My question here is - How the forces on the attached branches to the main line should be considered?
Should I calculate the forces for branch seperately? If yes, then what should be the data for this calculation?

Regards
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rohr2support
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Registriert: Mi 14. Sep 2011, 08:23

Re: Static fluid hammer analysis: Branches

Beitrag von rohr2support »

Hi
r2user hat geschrieben: How the forces on the attached branches to the main line should be considered?
Joukowski's approach is only valid for a single line without branches.
It calculates the pressure increase due to the gradient of mass-flow.
In case you have branches the pressure wave may continue into the branch even when there was no flow there before.

In this case I allways try to find the worst case combination by trying:
- Unbalanced pressure forces in the whole system
- Unbalanced pressure forces on each line separately

Best regards
robin59
Beiträge: 1
Registriert: Mo 2. Jul 2012, 12:01

Re: Static fluid hammer analysis: Branches

Beitrag von robin59 »

Hello Rohr2 support,

Would you please elaborate or give one example.

Regards
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rohr2support
Beiträge: 455
Registriert: Mi 14. Sep 2011, 08:23

Re: Static fluid hammer analysis: Branches

Beitrag von rohr2support »

Hi,

here is a short example, in this case you could create three different loadcases to find the worst case.
Please notice, as written above, that Joukowski’s approach wasn’t created for such scenario. To get more accurate results you should perform a dynamic fluid hammer analysis.

Loadcase 1
hammer1.jpg
Loadcase 2
hammer2.jpg
Loadcase 3
hammer3.jpg
Best regards
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