Environmental Engineering Reference
In-Depth Information
2500
90
80
R² = 0.9949
R² = 0.8157
2000
70
60
1500
50
40
1000
30
20
500
10
0
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1-ADFj
1-ADFj
Figure 7.13
Correlation of pipe flows (left) and pipe volumes (right) with the loss of demand - O20sn73
7
100
R² = 0.9068
R² = 0.9908
90
6
80
5
70
60
4
50
3
40
30
2
20
1
10
0
0
0
0.5
1
1.5
2
2.5
0
0.002
0.004
0.006
0.008
0.01
0.012
(1-ADFj)/Dj^2 (1/m2)
Tj(1-ADFj) (hrs)
Figure 7.14
Linear correlations of pipe velocities (left) and pipe volumes (right) - O20sn73
The figure shows that the pipe volumes expectedly correlate visibly worse than the flows.
Nevertheless, showing them against the loss of demand multiplied by the pipe residence time,
T
j
, will improve the correlation, as can be seen in Figure 7.14 on the right. Equally, the
relation between the pipe velocity and the loss of demand divided by the squared diameter
will show linear correlation (Figure 7.14, left). Thus, any pipe parameter when linked to the
flow can be expressed against the loss of demand. In networks having more buffer this
correlation will however be weaker.
Statistical analyses have been conducted to explore how typical pipe (hydraulic) properties or
their derivatives correlate to the loss of demand, and are there specific patterns existing for
various types of networks. The following pipe parameters were analysed:
1.
volume -
V
j
,
2.
flow -
Q
j
,
3.
velocity -
v
j
,
4.
friction loss -
h
f,j
,
5.
hydraulic gradient -
S
j
=
h
f,j
/
L
j
,
6.
power loss -
P
j
=
ρgQ
j
h
f,j
,
7.
residence time -
T
j
=
V
j
/
Q
j
,
8.
pressure buffer -
pb
j
calculated as in Equation 7.5,
9.
unit pressure buffer -
pb
j
/
L
j
,
10.
hydraulic loss area -
hl
j
, calculated as in Equation 7.6,
11.
pressure buffer index -
PBI
j
calculated as in Equation 7.7.
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