8 TECHNICAL DATA |
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SITRANS FX300 |
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8.1 Functional principle
Vortex flowmeters are used to measure the volumetric flow of gases, vapours and liquids at completly filled pipes.
The measuring principle is based on the Karman vortex street. The measuring tube contains a bluff body, behind which vortex shedding occurs. The frequency f of the vortex shedding is proportional to the flow rate v. The nondimensional Strouhal number S describes the relationship between vortex frequency f, width b of bluff body and the mean flow velocity v:
f= S . v b
The vortex frequency is recorded at the sensor and evaluated at the converter.
Figure 8-1: Functional principle
66 | www.siemens.com/flow | 06/2009 - SFIDK.PS.050.F2.02 A5E02100423 |