sites software application seminar __________________________ sites 2005 integrated development...
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SITES SOFTWARE APPLICATION SITES SOFTWARE APPLICATION SEMINARSEMINAR
____________________________________________________SITES 2005SITES 2005
INTEGRATED DEVELOPMENT ENVIRONMENTINTEGRATED DEVELOPMENT ENVIRONMENTfor
WATER RESOURCE SITE ANALYSIS
HOOD INLETHOOD INLET
The hood inlet routine has been revised. The adjustment is loosely based on the findings of Rice, 1967 with a linear transition assumed between smooth and rough pipe conditions.
The following slides show the old and new methods of computation.
H/D
Q/D(5/2)
rough
smooth
Cs
Pipe
flow
weir
Old routine method of compsOld routine method of comps
Slug Flow Coefficient - Hood Inlet
.01 .02
Manning’s “n”
1.05
1.56
Cs
2.0
Cs = 1.05+51(n-.01) for .01< n < .02
New hood method
H/D
Q/D(5/2)
rough
smooth
Cs
Pipe
flow
weir
New routine for comps of slug flowNew routine for comps of slug flow
Q/D(2.5) = (C1S(0.067) + CeH/D)(a/A)(H/D)(0.5)
C1 = 1.83
Ce = 0.6 or 1.35
S = slope of conduit
D = diameter of conduit in feet
H = head over invert in feet
a = wetted area of conduit related to flow depth in square feet
A = pipe area in square feet
NEH-5
a = D2/4{(cos-1 x)-(x)sin(cos-1 x)}
where x = (D-2H)/D
cos-1 x is in radians
In the slug flow region
H/D = Cs + C2(Q/D(2.5) )
C2 = 0.025
and Cs is defined by the following slide.
Slug Flow Coefficient - Hood Inlet
.01 .02
Manning’s “n”
1.05
1.56
Cs
2.0
Cs = 1.05+51(n-.01) for .01< n < .02
New hood method
The old routine broke smooth and rough at
“n” = 0.017.
When the slope of the pipe is very flat the equations developed for the stage - discharge relationships for the hood inlet no longer apply.
This occurs somewhere between 1% and 0% slope.
A slope of about 2.5% is the first set of data points on the hood inlet study where the equations would be valid.
1.56
H/D
Q/D(5/2)
Pipe f
low
wei
r
SMALL PIPE SLOPE S < 1%?SMALL PIPE SLOPE S < 1%?
(EQUATIONS NOT APPLICABLE)(EQUATIONS NOT APPLICABLE)
Approx.
Slug Flow Eq
1.0
Linear approximation below H/D = 1
H/D
Q/D(5/2)
Pipe f
low
wei
r
SMALL PIPE SLOPE S < 1%?SMALL PIPE SLOPE S < 1%?
(EQUATIONS NOT APPLICABLE)(EQUATIONS NOT APPLICABLE)
Approx.
Slug Flow Eq
1.0
END OF PRESENTATION END OF PRESENTATION