sites software application seminar __________________________ sites 2005 integrated development...

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