depth of flow

[jake07]

Hi, I am trying to work out the depth of flow in a pipe. I have the velocity, pipe gradient, pipe diameter, and flow entering the pipe. I know the depth of flow must be <0.75 diameter and I just need to put all into a spreedsheet for ease of calculation.

Thanks for the help!

 

[chicopee]

As it appears to be an open channel flow, use manning's equation to calculate the hydraulic radius. With that value and some trial and error procedure, you can work out the water level in the pipe. You may require two procedures for this trial and error. One procedure by assuming water is below at the mid point of the pipe cross setion and the other above the mid point cross section.

 

[jake07]

Hi, I am trying to work out the depth of flow in a pipe. I have the velocity, pipe gradient, pipe diameter, and flow entering the pipe. I know the depth of flow must be <0.75 diameter and I just need to put all into a spreedsheet for ease of calculation.

please note this is a circular pvc pipe part of a network

Thanks for the help!

 

[cvg]

http://www.lmnoeng.com/manning.htm

 

[gbam]

Jake07 --
You can download from FHWA Visual Urban. This program will provide you with normal depth in a circular section. Also you can refer to nomographs of partialy full pipes. These can be found in hydraulic text books. Find d/Dfull vs. v/Vfull etc....

Or as chicopee stated crunch out manning's by hand. Here are eqns. for circular section.

z=D/2-y: z is distance from center of pipe to water surface
y is depth of flow
x=cos^-1(z/r): x is angle from horz to watersurface
A=D^2/4: A area of flow
P=Dx: Wetted Perimeter
R=A/P:Hydraulic Radius

Q=1.49/n A R^(2/3) S^(1/2): Manning's Eqn.

Good Luck!, I wrote a visual basic routine to compute this.

 

[elev8848]

All:
see if my quick calculator helps at

http://www.hydrocalc.com