42
SeCtion b
SoFtware Manual
RetuRn to toC
MaCe HydRoMaCe 3000
Product Manual
43
RetuRn to toC
The HydroMace 3000 contains in-built equations for allowing users to measure
flow rate through rated structures such as flumes and weirs. The table below lists
the structures supported and the equations used to calculate flow rate.
All of the weir equations assume that the flow is fully contracted, meaning that
the approach channel is wide enough and deep enough that the proximity of
the floor and sidewalls to the weir opening does not affect the flow
(Tony L. Wahl,
Bureau of Reclamation Hydraulics Laboratory in Denver, Colorado, USA).
The equations used by the HydroMace 3000 and reproduced here are used
with permission of U.S. Dept. of the Interior, Bureau of Reclamation - Hydraulic
Investigations and Laboratory Services Group. For further information users are
encouraged to visit the following websites:
www.usbr.gov/pmts/hydraulics_lab/pubs/wmm/index.htm
www2.alterra.wur.nl/Internet/webdocs/ilri-publicaties/publicaties/Pub20/pub20.pdf
21.1.6 Add a “Flowrate (Weir)” channel type
Flume and Weir equation Summary
equation, cfs (head measured in feet) equation, kL/sec (m
3
/sec) ~ head
measured in meters
Contracted rectangular weir
Q=3.33(L-0.2h
1
)h
1
1.5
Q=1.84(L-0.2h
1
)h
1
1.5
Suppressed rectangular weir
Q=3.33(L)h
1
1.5
Q=1.84(L)h
1
1.5
V-notch weir, 90°
Q=2.49h
1
2.48
Q=1.34h
1
2.48
V-notch weir, 30°
Q=(8/15)(2g)
0.5
C
e
tan(θ/2)(h
1
+k
h
)2.5
Q=(8/15)(2g)
0.5
C
e
tan(θ/2)(h
1
+k
h
)2.5
V-notch weir, 45°
Q=(8/15)(2g)
0.5
C
e
tan(θ/2)(h
1
+k
h
)2.5
Q=(8/15)(2g)
0.5
C
e
tan(θ/2)(h
1
+k
h
)2.5
V-notch weir, 60°
Q=(8/15)(2g)
0.5
C
e
tan(θ/2)(h
1
+k
h
)2.5
Q=(8/15)(2g)
0.5
C
e
tan(θ/2)(h
1
+k
h
)2.5
Cipoletti weir
Q=3.367(L)h
1
1.5
Q=1.86(L)h
1
1.5
parshall flumes
Q=Ch
a
n
Q=0.552*Ch
a
n
replogle flumes
Q = K
1
(h
1
+K
2
)
U
Q = K
1
(h
1
+K
2
)
U
(long-throated flumes or
“ramp” flumes)
palmer-Bowlus flumes
Q = K
1
(h
1
+K
2
)
U
Q = K
1
(h
1
+K
2
)
U
Definitions, cfs
Definitions, kL/sec
Q = discharge, cfs
Q = discharge, kL/sec
L = weir width, ft
L = weir width, m
h
1
= upstream head, ft
h
1
= upstream head, m
C
e
= V-notch weir coefficient
C
e
= V-notch weir coefficient
k
h
= V-notch weir head adjustment factor, ft
k
h
= V-notch weir head adjustment factor, m
θ = V-notch weir angle, degrees
θ = V-notch weir angle, degrees
h
a
= Parshall flume upstream head, ft
h
a
= Parshall flume upstream head, m
C = Parshall flume coefficient
C = Parshall flume coefficient
n = Parshall flume exponent
n = Parshall flume exponent
g = acceleration due to gravity, 32.2 ft/s
2
g = acceleration due to gravity, 9.806 m/s
2
the V-notch weir and parshall flume coefficients used by the hM 3000 can be found in appendix a
2.
The
“Channel name”
dialogue box will
appear. Enter a channel
“Name”
in to the text
field (16 character maximum). This
“name”
will
also be displayed on the HM 3000 main LCD if
enabled. Click
“Continue”.
3.
In the
“Select depth channel”
dialogue box
use the drop down list to highlight the depth
channel from which the channel (named
“Parshall”
in this example)
will receive its value.
Click
“Continue”
and the “
Select weir type"
dialogue box will appear.
4.
Select the weir type that you
wish to configure. If you are setting
up a flow rate through a Parshall
flume, expand the
“Parshall
flume”
weir type and select the
appropriate flume width from the
expanded list.
1.
Select the
“Flowrate (using Weir)”
channel type from
the
“New channel”
dialogue box and click
“Continue”.
5.
Click
“Continue”
to complete the new channel.
6.
The
“Configure channels”
dialogue box will re-appear with the new
channel listed.
