Re =
Reynolds number (dimensionless) (ReynoldsNumber) calculated as shown in .
4.5.6 Reynolds number
Reynolds Number is a dimensionless value that represents the nature of the gas flow
within the pipe. Although the primary reason for calculating Reynolds Number is for
reflective path meters (transmitter head 2 for 3415 and 3416) profile-effect correction,
the value is calculated for all meter types.
Reynolds Number is calculated as shown in Equation 4-15
Reynolds number Equation 4-15:
Re = ℎ
4
,
, 10
4
Where
Equation 4-15
Re =
Reynolds Number (dimensionless) (ReynoldsNumber)
MAX =
maximum function that takes the maximum of the values within the brackets
PathFactor =
factor to (approximately) correct for velocity profile effects (0.94 for JuniorSonic
™
meters, 1.00 for SeniorSonic
™
meters) (dimensionless)
π
geometric constant, pi (dimensionless) (3.14159...)
Q
Raw
=
"raw" volumetric flow rate (m
3
/h) (QMeter)
ρ(P
f
,T
f
)
natural gas mixture mass density at the flow condition (either calculated as part of
internal AGA8 calculations or specified via (SpecRhoMixFlow) (kg/m
3
) (RhoMixFlow)
D
in
pipe inside diameter (m) (PipeDiam)
µ
dynamic viscosity (Pa•s) (Viscosity)
4.5.7 Base-condition volumetric flow rate
The base-condition volumetric flow rate is the result converting the flow-condition
volumetric flow rate to the base pressure-temperature condition.
This conversion requires (1) AGA8 calculations to be either performed internally (i.e., by
the meter) or externally (with the resulting compressibilities specified to the meter via the
SpecZFlow and SpecZBase data points), and (2) the flow-condition temperature and
pressure to be live or fixed. If AGA8 calculations are not performed (i.e., neither internally
nor externally) or the flow-condition temperature and/or pressure are/is not enabled, then
the base-condition volumetric flow rate is set to zero. The base-condition volumetric flow
rate is calculated as shown in Equation 4-16.
Measurement
Operations manual 29
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