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HOOD INLET. SITES SOFTWARE APPLICATION SEMINAR. __________________________ SITES 2005 INTEGRATED DEVELOPMENT ENVIRONMENT for WATER RESOURCE SITE ANALYSIS.
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HOOD INLET SITES SOFTWARE APPLICATION SEMINAR __________________________ SITES 2005 INTEGRATED DEVELOPMENT ENVIRONMENT for WATER RESOURCE SITE ANALYSIS
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.
Old routine method of comps Pipe flow H/D rough Cs smooth weir Q/D(5/2)
Slug Flow Coefficient - Hood Inlet New hood method 2.0 Cs = 1.05+51(n-.01) for .01< n < .02 1.56 Cs 1.05 .01 .02 Manning’s “n”
New routine for comps of slug flow Pipe flow H/D rough Cs smooth weir Q/D(5/2)
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 The old routine broke smooth and rough at “n” = 0.017. 2.0 New hood method Cs = 1.05+51(n-.01) for .01< n < .02 1.56 Cs 1.05 .01 .02 Manning’s “n”
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.
SMALL PIPE SLOPE S < 1%? (EQUATIONS NOT APPLICABLE) Pipe flow H/D Slug Flow Eq 1.0 Approx. weir Q/D(5/2)
SMALL PIPE SLOPE S < 1%? (EQUATIONS NOT APPLICABLE) Pipe flow H/D Slug Flow Eq 1.0 Approx. weir Q/D(5/2)