Flow Equations

[Rob231]

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.

 

[MortenA]

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

Best regards

Morten

 

[Rob231]

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

 

[vzeos]

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{(k[sub]e[/sub]/3.7D)+[(1.259/N[sub]Re[/sub])1/[√]f ][sup]E[/sup] }

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{(N[sub]Re[/sub]/ (1/[√]f)} -0.6

Rough pipe law: 1/[√]f= 4Log(3.7D / k[sub]e[/sub])

Critical Reynolds number: N[sub]ReCr[/sub]= 18.632075(D / k[sub]e[/sub]) Log(3.7D / k[sub]e[/sub])


1/[√]f = Fanning transmission factor
k[sub]e[/sub]=effective roughness, inches
E=pipe efficiency
N[sub]Re[/sub]=Reynolds number
N[sub]ReCr [/sub]= Critical Reynolds number

 

[Rob231]

Thanks much

 

[vzeos]

Rob231:

Don’t mention it.

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