| 摘要 |
A fluid flow meter, for example for measuring the velocity of an air flow, comprises a flow duct having a transverse vortex-shedding bar, the ultrasonic or other detector means for sensing the shedding of Karman vortices from the bar as the fluid flow passes the bar, and for converting the alternating output signal of the detector means into a signal of square-wave form of operating a digital counter, and one or more additional cross-members extending across the flow duct downstream of the flow section where the vortex-sensing means operates, the additional cross-member extending transversely to the vortex-shedding bar and being of cylindrical or aerofoil cross-section, or of rectangular or other cross-section having a flat upstream face parallel to the bar. The provision of the additional cross-member is found to improve the regularity of the vortex-shedding from the bar and hence the accuracy of the meter reading.
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