Apr. a3,1917 
The Venturi Flume 
123 
As shown in Table III, discharge values computed by equation (4) 
are higher than those obtained by experiment, because the equation does 
not contain a correction factor for the effect of contraction and fric¬ 
tion. Table III and figure 9, plotted from this table, show the correction 
factor (C) to be greater for high and low values of H d than for medium 
values of H d , and (C) increases as H a increases. To avoid confusion, 
coefficients (C) for H a ’s of 1.6 feet, 1 foot, and 0.4 foot, only, have been 
plotted in figure 9. The assumed limiting curves are shown in dotted 
Fig. 9.— Plot of values of coefficient C for V-notch Venturi flume. 
lines. The curves for the intermediate heads were assumed to have a 
straight line variation between the extreme curves and to change only 
in position. 
The equation of the upper limiting curve, 1.6 feet, referred to the 
point 0.96, 0.2 as the origin, is of the form 
y n ~ ax 
substituting values to find n and a, 
o.i n == 0.0167a 
0.03*—0.0015a 
0.1” 0.0167a 
0.03"™ 0.0015a 
rc^ log 11.13 
log 3-33 
2.00 
(o. 1 ) 2 =* 0.0167a 
3.33*=* 11.13 
n log 3.33=* log 11.13 
0.01 
0.0167 
*■0.6 
