Discharge coefficient of a semi-elliptical side weir in subcritical flow

• Published in: Flow measurement and instrumentation Vol. 22; no. 1; pp. 25 - 32
• Main Authors: Kaya, Nihat, Emiroglu, M. Emin, Agaccioglu, Hayrullah
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-03-2011
• Subjects: Channel flow; Discharge coefficient; Intake; Labyrinth; Semi-elliptical; Side weir; Labyrinth; Intake; Semi-elliptical; Discharge coefficient; Channel flow; Side weir
• ISSN: 0955-5986; 1873-6998
• DOI: 10.1016/j.flowmeasinst.2010.11.002

A labyrinth weir is an overflow weir, folded in plan view to provide a longer total effective length for a given overall weir width. The total length of the labyrinth weir is typically three to five times the weir width. In this study, a semi-elliptical labyrinth weir was used as a side weir structure. Rectangular side weirs have attracted considerable research interest. The same, however, is not true for labyrinth side weirs. The present study investigated the hydraulic effects of semi-elliptical side weirs in order to increase their discharge capacity. To estimate the outflow over a semi-elliptical side weir, the discharge coefficient in the side weir equation needs to be determined. A comprehensive laboratory study including 677 tests was conducted to determine the discharge coefficient of the semi-elliptical side weir. The results were analyzed to find the influence of the dimensionless weir length
L
/
B
, the dimensionless effective length
L
/
ℓ
, the dimensionless weir height
p
/
h
1
, the dimensionless ellipse radius
b
/
a
, and upstream Froude number
F
1
on the discharge coefficient. It was found that the discharge coefficient of semi-elliptical side weirs is higher than that of classical side weirs. Additionally, a reliable equation for calculating the discharge coefficient of semi-elliptical side weirs is presented.
A labyrinth weir is an overflow weir, folded in plan view to provide a longer total effective length for a given overall weir width. The present study investigated the hydraulic effects of semi-elliptical side weirs in order to increase their discharge capacity. A comprehensive laboratory study including 677 tests was conducted to determine the discharge coefficient of the semi-elliptical side weir. A reliable equation for calculating the discharge coefficient of semi-elliptical side weirs is presented.
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► Discharge coefficient of semi-elliptical side weir is higher than that of rectangular side weir. ► Discharge coefficient of side weir tested is lower than that of triangular labyrinth side weir. ► The discharge coefficient increases with increasing dimensionless weir length. ► The proposed equation was shown to be reliable for subcritical flow conditions. ► The intensity of the secondary flow is more dominant when the weir is a labyrinth type.