Gas flow through a 90 deg Elbow
I am a mechanical engineer, who does flow calculations occasionally. I have been asked to estimate the loss of pressure of a gas flowing through a 90 deg. elbow. Is there any ready formala for doing this, and is there any references somebody can help me. Thanks a lot for your assistance.

Re: Gas flow through a 90 deg Elbow
The Diffrence Between pressure inlet and pressure outlet will be total pressure loss.

Re: Gas flow through a 90 deg Elbow
My problem is I only know the inlet pressure, and may not have an oppurtunity to plug a pressure gauge after the outlet. I have to predict the pressure loss before the equipment is built. Any input is greatly appreciated.

Re: Gas flow through a 90 deg Elbow
Hi yes you can use an approximate loss coefficient approach.
The pressure head loss (h) can be approximated as... h = (k*u*u)/(2g) as h = dp/(rho*g) you can rearrange to get dp = k. 0.5*rho*u*u I assume you know or can calculate the density and average flow velocity. The value of k can be found listed in tables for differend bends/valve/etc. a 90 degree elbow has a k coefficient of 0.9 i.e. loss of pressure = 0.9 * dynamic pressure dp = 0.9 * 0.5* density * velocity squared This is described fully in the book 'mechanics of fluids' by B.S. Massey . ISBN 0412342804 alternatively you can calculate the friction factor from a moody chart and use a l/d approximation to find the pressure loss hf = f . (l/d) (vel squared/2g) Darcy weisbach equation try http://www.engineering.uiowa.edu/~fl...Chapter_10.pdf Good luck Tim, 
Re: Gas flow through a 90 deg Elbow
Tim,
Thanks a lot, appreciate your help. 
Re: Gas flow through a 90 deg Elbow
Have a look in:
Fluid Flow  Internal Flow Systems 2nd Edition by D.S. Miller This has pretty much everything you need to know about doing pipe flow calculations. Regards James 
All times are GMT 4. The time now is 04:26. 