i reached an impasse with determining friction slope in a pipe nomograph for hgl computation.
sf= (critical depth+pipe diameter)/2, then take that to intersect in the pipe nomograph.
so, a pipe flowing full has a normal depth of its dia., but i forgot how to get the sf from a full pipe. the sf values are much higher that one would expect.any help is appreciated
Once a pipe is full you no longer have open channel flow. You should be able to use the Mannings formula for full pipe flow.
I seem to remember a gravity pipe is considered full a .9D, and a completely full pipe is considered to be a pressure pipe.:-/
Yippers. No more open flow when the pipe is full.
Your maximum flow under gravity will occur in a little less than a full pipe.
The friction losses in a completely full pipe reduce it's capacity slightly.
When you go from gravity to pressurized you go from Mannings to Darcy.
Correction: Bernoulli or Darcy.
Sf = Q2 n2 / z2 A2R4/3
Sf = friction slope (ft./ft. or m/m)
Q = discharge (cfs or m3/s)
n = Manning’s roughness coefficient
z = 1.486 for use with English measurements only.
A = cross-sectional area of flow (sq. ft. or m2)
R = hydraulic radius (ft. or m) = A / WP
WP = wetted perimeter of flow (the length of the channel boundary in direct contact with the water) (ft. or m).