VOL. 3, NO. 2, APRIL 2008
ARPN Journal of Engineering and Applied Sciences
©2006-2008 Asian Research Publishing Network (ARPN). All rights reserved.
derived by Al-Khatib (1989) and herein only the final
results are presented:
2 2 . 3 2 3 H g b C d ⎟ 1 ⎠ ⎞ ⎜ ⎝ ⎛
Where Q = volume rate of flow; Cd = characteristic discharge coefficient, b = bottom width of the control section; g = acceleration due to gravity; H1 = the total energy head at the head measurement-section.
In recent years long-throated flumes have become the measurement device of choice for most applications (Reclamation, 1997), superseding Parshall flumes and other traditional devices. These older devices were
laboratory-calibrated, because the flow through their control sections is curvilinear. In contrast, streamlines are essentially parallel in the control sections of long-throated
flumes, making them amenable to straightforward hydraulic theory.
Significant advantages of long-throated flumes include (Wahl et al., 2000): Choice of throat shapes allows a wide range of discharges to be measured with good precision; Minimal head loss needed to maintain critical flow conditions in the throat of the flume; and E c o n o m i c a l c o n s t r u c t i o n a n d a d a p t a b i l i t y t o v a r y i n site conditions. g
Figure-1. Longitudinal Profile of a long-throated flume.
2.0 MATERIALS AND METHODS
Shahid Chamran University, Ahwaz, Iran. Figure-2 shows
2.1. Experimental setup
the plan view of the hydraulic laboratory and the flume which used in this research. Long-throated flumes were
In order to achieve the objective of this study a physical model is considered. Thus all series of experiments were conducted in a glass-walled horizontal flume 12.0 m long, 0.25 m wide and 0.50 m deep in the Hydraulic Laboratory at the Water and Science Collage of
manufactured from glass and placed at the distance of 2m from the upstream of the main flume system (the test section in Figure-2). In order to dissipating of the inflow energy, first flow passed through flow dissipater area, then traveled about 2 m to the test section.