Siemens SITRANS FUP1010 Operating Instructions Manual page 18

Description
3.3 Theory of Operation
①
②
③
④
∅° = sin
T = 2 * ID / (VOS * cos ∅)
L
V = V
F
Flow Profile Compensation
Another important consideration is that the ultrasonic flow meter has to compensate for the
flow profile to maintain calibration accuracy. Shown below is a graphic of a "fully-developed"
flow profile. Note that the fluid velocity increases toward the center (axis) of the flow stream.
①
Fluid velocity near the axis of the flow stream tends to be greater.
16
Velocity of Sound
Flow Vector
Pipe ID
WideBeam Sensors
(VOS / V )
-1
phase
* DT / (2 * TL)
phase
Where: VOS = Velocity of sound in liquid
V
phase
ID = Pipe inside diameter
T = Transit time in liquid
L
DT = Measured Transit-Time difference
V = Flow Velocity
F
Operating Instructions, 03/2012, A5E02951522-02
= Phase velocity of sensor
FUP1010 IP67 Portable