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Abstract

A vortex-shedding flowmeter in which a liquid or gas to be metered is conducted through a flow tube having a shedding body transversely supported thereon. Torsionally-supported behind the body and spaced therefrom by a gap is a drag-actuated sensor which includes a pair of parallel legs symmetrically disposed with respect to the fulcrum axis of the sensor, this axis being normal to the longitudinal axis of the tube. In operation, as the incoming fluid stream is divided by and flows past the shedding body, it creates a stagnant zone in the gap that is initially aligned with the tube axis. But as vortices are successively detached from the body and appear alternately on either side of the gap, the low pressure region produced by each vortex acts to draw the stagnant zone in front of the adjacent leg of the sensor, the fluid flow then going around and past the other leg, thereby developing a torque about the fulcrum axis. The torques are developed alternately in the clockwise and counterclockwise directions, causing the torsionally-supported sensor to oscillate at a frequency proportional to the flow rate of the fluid. These oscillations are converted by a transducer coupled to the sensor into a corresponding electrical signal.

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First Claim