Vortex flowmeter consists of vortex generator (non-streamlined throttle), detection probe and related electronic circuits designed in the flow field. When the fluid flows through the vortex generator, the boundary layer separates and two rows of vortices are alternately formed on both sides (the vortices rotate in opposite directions), which is called Carmen vortex street.

This vortex is regular, and the frequency of Karman vortex street is directly proportional to the velocity of fluid. The relationship is: f = st x v/d. F is the frequency of vortex street, v is the average velocity on both sides of vortex generator, and st is the Stern Rohal coefficient (constant). These alternating eddy currents also generate a series of alternating negative pressure, which acts on the detection probe, thus generating a series of alternating electrical signals, which are converted, shaped and amplified by the front-end amplifier, and then output pulse frequency signals proportional to the eddy current synchronization. Vortex flowmeter is an instrument for measuring flow according to the relationship between vortex frequency and flow generated by vortex generator.