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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

P=15.24 cm, Upstream Slope= 2:1

0.98

0.96

0.94

Cd

0.92

0.9

Flum e I (D.S. is Vertical )

Flum e L (D.S. is 6:1 )

0.88

Flum e N (U.S. is 10:1 )

0.86

0

0.2

0.4

0.6

0.8

1

H1/L

Figure- 9. Coefficient discharge of flumes I, L and N as a function of downstream slope and H1/L when step height (p) is 15.24 cm and upstream slope is 3:1.

P=15.24 cm, Upstream Slope= 3:1

1.02

1

0.98

0.96

Cd

0.94

0.92

0.9

Flume J (D.S. is Vertical )

0.88

Flume M (D.S. is 10:1 )

0.86

0

0.2

0.4 H1/L

0.6

0.8

1

Figure -10. Coefficient discharge of flumes J and M as a function of downstream slope and H1/L when step height (p) is 7.62cm and upstream slope is 3:1.

With respect to the these Figures, it can say for a constant upstream slope and step height, any increasing in the downstream slope correspondingly leads to a increasing in the discharge coefficient. Therefore in order to increasing of the passing discharge through flume, it is better to increasing the downstream slope of the flume.

4.0 CONCLUSIONS Long-throated flumes are

a well-developed

technology that provides economical and flexible water measurement capabilities for a wide variety of open- channel flow situations. The structures have low head loss requirements among other advantages (Wahl et al., 2000).

The discharge coefficient of long-throated flume depends on the many parameters such as upstream and downstream slope. In this research in order to investigate the effects of these parameter different laboratory tests

were conducted with 11 kind of long-throated flumes. Summarizing the findings derived from the different experiments is governed by following parameters:

  • The flow measurement error.

  • The effect of upstream slope of long-throated flume on its discharge coefficient.

  • The effect of downstream slope of long-throated flume on its discharge coefficient.

The results of the present study revealed that the average flow measurement error was 1.6 %. With this respect, this structure can be used for flow measurement successfully.

The investigation of upstream slope show when the other parameters such as downstream slope and step height are constant, decreasing the upstream slope lead to the increasing the discharge coefficient.

69

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