[b]Relations for the Net Expansion Factor Y[/b]
[b]Relations for the Net Expansion Factor Y[/b]
(OP)
I'm looking for relationships (empirical or theoretical) for the net gas expansion factor Y as a function of downstream and upstream pressures and the pipe resistance coefficient K among others for the compressible fluid flow through pipes. All I could find was related to flowmeters with a diameter change...
Also does the Robert Kern formula ring a bell to anyone in relation to calculations of Y for critical flow conditions?
Thank you!
Also does the Robert Kern formula ring a bell to anyone in relation to calculations of Y for critical flow conditions?
Thank you!





RE: [b]Relations for the Net Expansion Factor Y[/b]
You can get the book ($36) or the software from
http://www.cranevalves.com/store.htm
Larry
RE: [b]Relations for the Net Expansion Factor Y[/b]
RE: [b]Relations for the Net Expansion Factor Y[/b]
We use AFT ARROW for compressible flow modeling. It actually calculates the change in properties with fluid expansion, and agrees well with examples in Crane.
Larry
RE: [b]Relations for the Net Expansion Factor Y[/b]
After a quick look on the internet, looks like this software has something like that built in
http://www.edstech.com/under.html
Also happened to find this which sounds like they took Crane's graphs and built a subroutine from that.
http://melcor.sandia.gov/ref/cnd/cndreference.htm
Based on what OldSohioEngr points out, guess you would have to create your own equations unless you find someone that is willing to share.
I saw you had a similar post on another forum. You mentioned about comparing data to another source. I'm curious to know the other source to which you refer.
RE: [b]Relations for the Net Expansion Factor Y[/b]
Anyway I found an equation in the form of Y = m deltaP/P + 1
with m in the form a/(K+1) + b, with a and b for gamma of 1.3 and 1.4. However I'm doing calculations for propylene where you have Cp/Cv = 1.15, quite far from the 1.3 given by Crane. My idea was to find equations relating Cp/Cv with all the other factors.
My other "source" (although the term is not quite accurate) is the equations used by the spreadsheet from October 2002 Chemical Engineering magazine as suggested by TD2K on another thread (Thread798-51260). However the results I obtained are quite different when compared to Crane and I don't really understand the basis of the spreadsheet equations. Since I found other one in a textbook, I was wondering which were used in Crane...
I'm not sure all this is clear...
RE: [b]Relations for the Net Expansion Factor Y[/b]
RE: [b]Relations for the Net Expansion Factor Y[/b]