Environmental Engineering Reference
In-Depth Information
0
0
0
p
p
p
i
,
f
i
,
f
min
∆
Q
=
k
−
=
k
−
Q
5.12
i
,
f
i
i
i
,
t
ρ
g
ρ
g
ρ
g
5.4.4 Balance of head losses in loops
After the failure of pipe
f
, the balance of friction losses in each loop of a network changes as
follows (respecting the loop orientation):
k
k
k
(
)
∑
∑
∑
h
=
h
+
∆
h
=
0
⇔
∆
h
=
0
5.13
f
,
j
,
f
f
,
j
f
,
j
,
f
f
,
j
,
f
j
=
1
j
=
1
j
=
1
h
f,j
is the initial friction loss of pipe
j
, and
h
f,j,f
the value after the failure. Additional impact of
pumps and valves should be included in Equation 5.13 if they are part of the loop.
Furthermore, Equation 5.13 will be invalid in case of the loop to which pipe
f
belongs.
Nevertheless, Equation 5.13 will be valid for two adjacent loops sharing pipe
f
, and
effectively merging into one bigger loop after that pipe has been closed.
Figure 5.8
Net 10, no-failure - left: flow-demand (l/s), right: h
f
/L-p/ρg (mwc)
Figure 5.9
Net 10, failure J7-J3 - left: flow-demand (l/s), right: h
f
/L-p/ρg (mwc)
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