ratio of orifice hole diameter
to pipe diameter Nomenclature
A flow section area
Ac contracted area of flow
Ao orifice area
a area
B average width
bc width
C Chezy factor, general coefficient, concentration of a tracer, or constant
Ca gate angle correction factor
Cc contraction coefficient
Cd discharge coefficient
Ce effective discharge coefficient
Cv velocity of approach coefficient
Cva coefficient to account for exclusion of approach velocity head
Cvf velocity coefficient caused by friction loss
c velocity of sound
D pipe diameter
dv distance water will travel at a given velocity in a pipe of constant diameter
E specific energy
E%QCs error in percent comparison standard discharge
E%QFS error in percent full-scale discharge
e a subscript denoting "effective"
egl energy grade line
F Froude number
Fb canal freeboard
Fc critical Froude number
Fp pressure force
f friction factor
Go gate opening
g acceleration caused by gravity
H total energy head
Hc critical total energy head
h head or height
ha measuring head
hb submergence head
hb/ha submergence ratio
hc critical head
hcm critical hydraulic mean depth
he effective measurement head
hf head loss
hm hydraulic mean depth
hv measured velocity head
h1e h1 + kh
h1 head measure above a weir crest (upstream head)
ªh upstream head minus downstream head (differential head)
hf(1-2) friction head loss between two stations
hgl hydraulic grade line
K constant
k boundary roughness size
kb correction factor to obtain effective weir length
kh correction factor to obtain effective head
L length
Lb cross-sectional width
Le L + kb or effective crest length
N sample number
n friction or roughness factor
PH pinion height
Pw wetted perimeter
p pressure or height of crest above approach invert
Q discharge
Qa actual discharge
Qc critical discharge
Qcs comparison standard discharge
Qs suppressed orifice discharge
Qeq discharge computed using measured heads and the regression equation
QFS full scale or maximum discharge
Qind indicated discharge from device output
Qmax maximum discharge
Qmin minimum discharge
Qt theoretical discharge through an orifice
ªQ% percent deviation of discharge
q unit or partial discharge
Re Reynolds number
Rh hydraulic radius
r ratio of suppressed portion of the perimeter of an orifice to total perimeter
r radius of curvature
S slope or estimate of standard deviation
So invert or bottom slope
Sws water surface slope
s estimate of standard deviation
T time
T top water surface width
Tc top water surface width at critical conditions
t time
td downstream travel time of the acoustic signal
tu upstream travel time of the acoustic signal
ªt difference in times
U equation coefficient or exponent
V mean velocity
Vc critical velocity
Vaxial average axial velocity of water flow
V0 volume
W weight
Xavg mean of a set of values
Xind each individual value from a set of values
Z potential energy head
ratio of orifice hole diameter
to pipe diameter
unit weight of water
angle
kinematic viscosity
standard deviation