Page 82 - AJWEP-22-6

Heidarnejad, et al.

Table 1. Summary of predictive equations for the discharge coefficient of labyrinth weirs
References Equation Recommendation
Darvas 20 Q H
C= max Triangular labyrinth weir; 0.2 ≤ T ≤ 0.6 ;
d 2 (II)
Wh P
max
side wide angle ≥0.8α
max
Lux and Q w
Hinchliff 21 C= cycle Labyrinth weir with one cycle; > 2 ; k is
d
w P
(III) the apex shape constant
P wgH 1.5
w T
+k
P
Melo Q Circular labyrinth weir; 1≤k θ-CW ≤1.4
et al. 22 C= 1.5 (IV)
d
k W 2gH
¸-CW T
Crookston 23 Labyrinth weir with half-round and
))
H T (B( H T C (V) quarter-round crests; A, B, C, and D are
C=A( ) P +D
d
P curve-fit coefficients; 6 ≤α ≤35
Emiroglu Triangular labyrinth weir with one cycle
et al. 24 C=(18.6 23.535[− d L 0.012 +6.769[ L 0.112 −
]
]
B l
W 4.024 2.155 − 1.431 (VI)
0.502( ) +0.0094sin¸ − 0.393Fr 1 )
y 1
Karami y Asymmetric triangular with one cycle
et al. 25 C=0.012( 1 − 2.5 +0.881r ¸ 0.248 +2.97Fr 1.79 (VII)
)
2
d
W
Bonakdari P L L Triangular labyrinth weir
et al. 26 C=0.466+0.388 − 0.183 − 0.022 +
d
y W y
0.31Fr+0.12sinθ (VIII)

discharge equation (Q = 1.417⋅H ) was validated, with tests was conducted using 12 models of TALW with an
2.5
head measurements accurate to ±0.1 mm. Calibration expanded middle cycle. Table 3 represents parameters
tests across the experimental flow range (5–50 L/s) included for the tests.
confirmed flowmeter deviations within ±0.15 L/s, A schematic representation of the labyrinth weir is
ensuring high-fidelity discharge data. The bottom provided in Figure 2, detailing its geometric parameters
of the flume was a fixed-bed type and maintained as relative to the weir crest. A represents the inside apex
horizontally as practically possible. width, t indicates the wall thickness, α is the sidewall
w
Water was initially pumped from the groundwater angle, W corresponds to the apron width, w denotes
tank into the head tank, from where it flowed through the cycle width, P represents the weir height, and T
a 0.3 m diameter pipe toward the inlet of the test flume, indicates the pier thickness.
regulated by a globe valve. Water entered the flume at a
low flow rate, gently passing over the weir. By varying 2.2. Dimensional analysis
the flow rate, the hydraulic conditions at the upstream, The values of C for TALW can be considered a function
d
over, and downstream of the weir were recorded. dependent on the following parameters:
Ultimately, water exited the flume into a downstream C =F(Q, w , w , B, H , g) (IX)
channel, entered the pumping tank, and was recirculated d 1 2 d
back into the system. A representation of the geometry Where Q is the flow rate, w is the inside apex width
1
dimension is illustrated in Figure 1B. A series of 120 of the middle cycle, w is the inside apex width of the
2

Volume 22 Issue 6 (2025) 76 doi: 10.36922/AJWEP025120081