Need to design an elbow

[polezero]

I have to design an elbow that is used to join pipes. I am using the language Modelica. Since i want to make the model to work at different elbow angles ranging from 0 to 90 Deg, i need to know the formula that relates this varying angle with the pressure loss coefficient, K.

 

[ione]

Be careful with that stuff

http://www.mathworks.com/access/helpdesk/help/toolbox/physmod/hydro/ref/elbow.html

 

[polezero]

hello,

Thanx for the reply. i have tried the formulas from mathworks. there its written for a 90 Deg elbow the loss coefficient is K=30*f.For elbows with other angles there is a correction factor which is Kcorr=a(0.0142-3.703e-5a). Here a is the angle between 0 and 90. Next the revised loss coefficient is K=30*f*(a(0.0142-3.703e-5a)).Now, doesnt this term vanishes for a=0? Or i just have misinterpreted it !!..

 

[ione]

For a=0 which elbow have you got? No elbow = no minor loss!

 

[racookpe1978]

Really think about how "hard" you are working: In 99.8 percent of piping systems actually built, only two elbows are used: a 90 and a 45. Yes, we occasionally cut these short by a little bit, but the flow loss calc's aren't all that accurate. (An 85 (if it were bad pipe fit up!) degree elbow makes no real difference in the flow than the 90 in front of it or the 92 behind it.)

So use the value from the reference in your model - which is approximate anyway) for those two cases.

 

[jte]

What class is this for? Or can you be more specific about your real-world application?

jt