Slug Flow Formula (User Guide)

Posted by: Arredondo

Slug Flow Formula (User Guide) - 08/28/14 04:36 AM

Hello!

I'm checking the slug flow formula included in the User Guide of CAESAR II and I have a question about it. I would like to know if the Dynamic Load Factor is included in such formula or not.

I've deduced the general formula (depending on the angle of the elbow) and fits with the User Guide's formula considering the User Guide include the DLF.

Thanks
Saludos
Posted by: Dave Diehl

Re: Slug Flow Formula (User Guide) - 08/28/14 08:21 AM

The formula in the CAESAR II User Guide provides the magnitude of the applied load. The applied load is multiplied by the dynamic load factor (DLF) to develop the induced load. Evaluating the response to this induced load (may) predict the maximum (modal) dynamic response to this transient slug load.
Posted by: Arredondo

Re: Slug Flow Formula (User Guide) - 09/01/14 02:59 AM

Hello Dave,

Thank you for the answer. We are checking again the formula and we can't find the mistake/s in our calculation. "Our" formula is half of User Guide's formula.

Can you provide the deduction of the formula or a technical reference? A drawing would be perfect!

Thank you very much.
Posted by: Pablo_GH

Re: Slug Flow Formula (User Guide) - 09/01/14 05:38 AM

Formula, according to COADE notes, should be:
F= dp/dt = Ro*V2*A*((1-cos(O))/2)^1/2
As you see, doesn't match with the one given in the user guide's manual, wich is double.
Regards
Posted by: Pablo_GH

Re: Slug Flow Formula (User Guide) - 09/01/14 08:28 AM

Originally Posted By: Navendu Shrivastava
Dear Piyush,
Two-phase flow analysis must further be extended to get liquid slug length, gas length and liquid slug velocity.
Unbalanced force due to Slug impact is equal to change in momentum with respect to time. It can be calculated by the formula :
F = dp/dt = rho. sq.V . A [(1- COS theta)/2]1/2
Where rho– Fluid Density
V – Slug Flow Velocity
A – C/S Area
theta– Bend Angle
Posted by: mariog

Re: Slug Flow Formula (User Guide) - 09/02/14 03:12 AM

I attached an interesting presentation on the subject (even there the focus is on Olga software)
Posted by: Dave Diehl

Re: Slug Flow Formula (User Guide) - 09/02/14 08:06 AM

The CAESAR II User Guide (pg. 614) shows the formula for the APPLIED (static) load as rho*V^2*A*[2(1-cos(theta)]^0.5. This formula does not address the INDUCED load which may be DLF*(Applied Load).
The CAESAR II seminar notes had an incorrect listing for this magnitude.
With a little work, the formula in the User Guide matches that found in Kellogg's Design of Piping Systems page 285.