×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Flow Equations

Flow Equations

Flow Equations

(OP)
Hey all,

I'm looking for a couple of equations for fluid flow in a gas pipeline that have so far been difficult to find.
They are the "New IGT Equation", which is apparently not the same equation as the IGT distribution equation, and there's not much more I know about that one. The other I believe might be an iterative approach to the General Flow Equation, but it is named "Point Transition Model". Any thoughts on what these equations might be would be, even on places to look for said equations would be helpful. Thanks.

RE: Flow Equations

Are you talking pressuredrop or how to solve a network of pipes for different border conditions?

Best regards

Morten

RE: Flow Equations

(OP)
Pressure drop, using equivalent lengths and such so that it is basically a straight length of pipe.

RE: Flow Equations

Rob231,
The New IGT Equation also known as the IGT Transition equation can be found in:
Steady Flow in Gas Pipelines,  Technical Report No. 10, by Uhl, A. E., et al.,  Institute of Gas Technology, Chicago, 1965.  Top of page 136.
The equation is:

 1/√f= -4Log{(ke/3.7D)+[(1.259/NRe)1/√f ]E }

The New IGT Equation is very similar to the Colebrook equation except the efficiency factor, E, is applied only to the smooth pipe term as an exponent.  The Colebrook equation does not include an efficiency factor but engineers frequently apply the efficiency factor as an overall coefficient which can lead to poor results.

The point transition model assumes that the transmission factor undergoes transition very abruptly and that the flow regime transition occurs at the intersection of the smooth pipe flow law and the rough pipe flow law.  To determine the correct flow regime, a third equation is used to calculate the critical Reynolds number, i.e., the Reynolds number at which the transition point occurs.

Smooth pipe law: 1/√f= 4Log{(NRe/ (1/√f)} -0.6           

Rough pipe law: 1/√f= 4Log(3.7D / ke)

Critical Reynolds number: NReCr= 18.632075(D / ke) Log(3.7D / ke)


1/√f = Fanning transmission factor
ke=effective roughness, inches
E=pipe efficiency
NRe=Reynolds number
NReCr = Critical Reynolds number


RE: Flow Equations

(OP)
Thanks much

RE: Flow Equations

Rob231:

Don’t mention it.

If you don’t mind my asking, where did you come across the equation names that you used?  

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources