Civil Engineering Reference
In-Depth Information
Fig. 26-18.
Combining flow—branch angle 45
—loss coefficient
K
23
(
Source:
Reference 7; cour-
tesy of the BHR Group Limited)
Bulk cavitation
•
Flow curvature cavitation
•
Surface roughness cavitation
•
Turbulence cavitation
•
For a detailed discussion of cavitation, the reader is referred to Miller.
7
For this
text, the equations and curves presented by Miller are reproduced here.
Cavitation of Butterfly Valves
The incipient velocity (
U
ir
) and critical velocity (
U
cr
)
are shown in Figure 26-31 (page 928). The base conditions are a valve diameter of
0.321 m and an upstream head minus the vapor pressure head of 50 m. To correct
these for other valve sizes and head use:
h
h
u
0.39
ƒ
v
U
or
U
CU
(26-18)
i
c
1
r
50
The value for
C
1
is shown in Figure 26-32.
