Civil Engineering Reference
In-Depth Information
V
1
V
2
D
1
D
2
.6
.5
.4
.3
2
H = K
E
V
2g
L
2
.2
.1
0
1.0
2.0
2.5
3.0
1.5
3.5
4.0
DIAMETER RATIO D /
12
[( )]
D
2
2
V
2
[( ) ]
D
2
2
2
V
1
= K
2
H=K r-
1
-1
2
D
2g
D
2g
1.4
1
2
UPPER LIMIT
1.2
1.0
LOWER LIMIT
.8
.6
V
1
0
V
2
D
.4
2
D
1
L
.2
0
50
90
100
110
120
0
10
20
30
40
60
70
80
0 IN DEGREES
Fig. 26-5.
Headloss coefficients for contractions and enlargements (
Source:
Reference 6; courtesy
of the Hydraulic Institute)
nozzles for the flow-measuring Venturi tubes. Typical
K
L
values vary from 0 to 10 for
area ratios of 0.8 to 0.1 for recovery angles from 5 to 7 degrees. Figure 26-10 illus-
trates the range of
K
L
values based on area ratios and recovery angles.
Miller
7
developed similar curves for a variety of differential flow meters. These are
shown in Figure 26-11.
