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| Working
Principle |
When a column body placed in flowing fluids in pipe, a series
of vortices will be generated alternately on each side of
the object as shown as below, these eddies known as ＾Karman
Vortices￣, the frequency of the vortex shedding is related
to the velocity of the fluid and the width of the body. Expressed
by formula as below:
f =St，v/d
Thereinto f ---- frequency of Karman Vortex shedding
St ---- Strouhal number
v ---- velocity
d---- width of column object
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Because the frequency of the vortex
shedding is proportional to the velocity, it can be used to
calculate the instantaneous flowrate .
Strouhal number is a very important coefficient in the Vortex
Flowmeter. In the range of straight line of St「0.17 in curve,
frequency of vortex shedding is proportional to the velocity,
so as long as the frequency (f) be detected, the velocity
(v) will be obtained, and volumetric flowrate will be got
according to v.
For KTLU Vortex Flowmeter, its frequency of the vortex shedding
was detected by the stress force which exerted on the sensor
(probe) using the piezoelectric unit which is built in sensor.
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