Mechatronics, Industrial Control & Instrumentation

The Principle of Operation of a Vortex Flowmeter

If a bluff (non-streamlined) body is placed in a flow, vortices detach themselves at regular intervals from the downstream side as illustrated in the diagram below:

Principle of operation of a vortex flowmeter
Figure: Vortex shedding flowmeter

In flow measurement the vortex shedding frequency is usually a few hundred hertz (Hz). At Reynolds numbers over 103 the volumetric flowrate, Q, is directly proportional to the observed frequency of vortex shedding f, i.e.

Q = Kf

Where K is a constant determined by the pipe and obstruction dimensions.

The vortices manifest themselves as sinusoidal pressure changes which can be detected by a sensitive diaphragm on the bluff body or by a downstream ultrasonic beam.

Related: How to Connect a DP (Differential Pressure) Flow Sensor to a DP Transmitter

This flowmeter can work at low Reynolds numbers, has excellent turndown (normally 15:1) , no moving parts and minimal head loss.

You can also read: Types of Sensors used in Measurement and Process Control

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John Mulindi

John Mulindi is an Industrial Instrumentation and Control Professional with a wide range of experience in electrical and electronics, process measurement, control systems and automation. In free time he spends time reading, taking adventure walks and watching football.

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