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VOL. 3, NO. 2, APRIL 2008

ISSN 1819-6608

ARPN Journal of Engineering and Applied Sciences

©2006-2008 Asian Research Publishing Network (ARPN). All rights reserved.

www.arpnjournals.com

3.2. The Effect of upstream slope of long-throated flume on the discharge coefficient (Cd)

The downstream slope was 6:1 and step height (p) was 7.62 cm (Flumes D, E and F).

In order to investigate of upstream slope of long- throated flume on the discharge coefficient (Cd), a comparison was made between calculated discharge coefficient of flume when the upstream slope of the flume was reduced from 1:1 to 2:1 and 3:1 at two same conditions as following:

The downstream slope was vertical and step height (p) was 15.24 cm (Flumes H, I and J)

Figures 6 and 7 show the discharge coefficient as a function of H1/L, where H1 is the energy head in the upstream of the flume and L is the throat length of the flume.

P=7.62 cm, Downstream Slope= 6:1

1.00

0.98

0.96

0.94

Cd

0.92

0.90

Flume D ( U.S. Slope 1:1)

Flume E ( U.S. Slope 2:1)

0.88

Flume F ( U.S. Slope 3:1)

0.86

0

0.2

0.4

0.6

0.8

1

H1/L

Figure- 6. Coefficient discharge of flumes D, E and F as a function of upstream slope and H1/L when step height (p) is 7.62 cm and downstream slope is 6:1

P=15.24 cm, Downstream Slope=Vertical

1.02

1.00

0.98

0.96

Cd

0.94

0.92

Flume H ( U.S. Slope 1:1)

0.90

Flume I ( U.S. Slope 2:1)

0.88

Flume J ( U.S. Slope 3:1)

0.86

0

0.2

0.4

0.6

0.8

1

H1/L

Figure- 7. Coefficient discharge of flumes H, I and J as a function of upstream slope and H1/L when step height (p) is 15.24 cm and downstream slope is vertical.

The upper, middle and lower curves in the Figures 6 and 7 are related to the upstream slope of 1:1, 2:1 and 3:1 respectively. With respect to the these Figures,

any decrease in the upstream slope correspondingly leads to a decrease in the discharge coefficient. This is consistent with the hypothesis that decreases of upstream

it can say for a constant downstream slope and step height,

67

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