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This work made an attempt to integrate the sensors with the
vortex shedder. This process involves the selection of the
sensor location and the development of a scheme to reduce the
signals measured.For the Reynolds numbers studied, the drag
coefficient obtained is 1.65. The Strouhal number is
0.100±0.0025. A good linearity of vortex shedding frequency
versus the flow velocity maintains at locations 4 and 6, and the
difference of standard deviations of the Strouhal number are
less than 0.5%. Locations 2 and 4 give higher signal-to-noise
ratio. The pressure fluctuation coefficients appear to be in the
range of 0.02 to 0.3, and the largest intensity of pressure
fluctuations are measured at location 5.The desired location of
frequency sensor is selected to be at location 4 or 5. Although
the signal quality obtained at location 5 get less satisfactory
as the Reynolds number higher than 20000, the spectral analysis
of the signals obtained show that the component of low frequency
can be separated from the vortex shedding frequency.With the
introduction of large amplitude low-frequency structural
vibration to the entire flow system externally, the component of
vortex shedding frequency in the signal measured was
predominated by the low frequency components. This problem was
remedied by a signal reduction scheme proposed that the signals
measured on the two sides of the extended plate were subtracted
each other.A concern of accumulation of dirt on the vortex
shedder after a period time of usage was studied in this work.
Through a series of experiments with modified T-shape vortex
shedder that simulating the flowmeter, the results obtained show
that the signal quality does not degrade, but the Strouhal
number is affected substantially. The Strouhal number obtained
from the T-shape model type 3 is 7% less than the one obtained
from type 0.Higher the turbulence level lower the quality of the
signal. However, the variations of turbulence level does not
influence the linearity of Reynolds number and the Strouhal
number significantly. The Strouhal number obtained at the
turbulence level of 8% is 6% less than the one obtained in the
situation of low turbulence level.
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