Design of a Pipe
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Transcript Design of a Pipe
Design of a Pipe
7
101
1
Runoff 102
8
2
3
4
102
9
10
103
11
5
6
In a tree network, each node can have only one outflow
link. Therefore we use the convention that link
numbers are the same as the upstream node number.
Get the Maximum Inflow
If no inflow hydrograph exists the user
can specify a peak flow for the design
Use Hydrograph|Add Runoff to update
Inflow hydrograph
Uniform Flow in Pipes
2
1
M
3
Q
AR S 0 2
n
D2
sin
A
8
PD
2
D
y 1 cos
2
2
Solve for y0 using
3
2 Q 5
f sin
Q
full
2
5
0
Critical Depth in Pipes
Solution for Ycr is based on the
minimum energy criterion
A3 Q 2
f y
0
T
g
T 2 Dy y 2
T
2 tan
D 2y
1
Q 2T
1
3
gA
A Trial Pipe Design
Table of feasible
designs for given Q
and ‘n’
Double click on a row
to test trial design
Click [Design] to
get results of partfull flow analysis
Surcharged Pipes
Due to closed top boundary resistance increases
as depth y approaches diameter D.
At y = 0.81963 D
Q = Qfull
1.2
Q/Qfull
1
0.8
When y = 0.93815 D
Q = 1.07571 Qfull.
0.6
0.4
0.2
0
0
0.5
y/D
1
Surcharged Pipes
Energy line
Q > Qfull
Water surface
Q = Qfull
Q < Qfull
MIDUSS 98 assumes uniform flow for
part-full pipes
Exercise 4
Design a pipe to carry 2 c.m/s when running
75% full with a gradient of 0.4% and n =
0.013
Check for surcharged hydraulic grade line if
discharge increases to 3 c.m/s