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Measuring principle and flow meter design
6 Measuring principle and flow meter design
6.1 Measuring principle
The measuring principle is based on the generation of Coriolis forces. For this purpose, a
driver system (E) excites the two measuring tubes (M1, M2) in their first resonance
frequency. Both pipes vibrate inversely phased, similar to a resonating tuning fork.
Q
inlet
Fig. 2: Coriolis principle
M1,M2 Measuring tubes
S1, S2 Pick-offs
F1, F2
Mass flow
The fluid flow through the vibrating measuring tubes generates Coriolis forces (F1, -F1
and F2, -F2) that produce positive or negative values for the tubes on the inflow or
outflow side. These forces are directly proportional to the mass flow and result in
deformation (torsion) of the measuring tubes.
1
Fig. 3: Coriolis forces and measuring tube deformation
1
2
3
22 / 194
S1
-F1
F1
M1
M2
A
Coriolis forces
A
E
Measuring tube mount
Fluid
Measuring tube
A5E52748375-AA, 2023/09
outlet
-F2
-A
S2
F2
E
E
Driver system
Direction of measuring tube
A
vibration
Q
Direction of fluid flow
2
A
E
α
F1
3
A
Rotational axis
E
F1, F2
Coriolis forces
α
Torsion angle
Measuring principle
3
F2
1
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