Unveiling the Secrets of Vortex Flowmeters: Measuring Principle Analysis

Among the velocity flowmeters for measuring fluid flow, the vortex flowmeter is a vital tool. This flowmeter is widely used in industrial pipelines to measure the flow of medium fluids, whether it is gas, steam or liquid. Due to its advanced performance and good compatibility with DCS systems, the vortex flowmeter is considered to be a very effective flow meter. The working principle of the vortex flowmeter and its application in industrial production will be analyzed below.


The vortex flowmeter is mainly composed of three key components: vortex generator, frequency detector and signal converter. The functions of these components are very diverse. On the one hand, they can output 4-20mADC signals, and on the other hand, they can also output pulse voltage signals. The measurement principle is to place a non-fluid type bluff body in the vertical flow direction of the flowing fluid, and then separate the fluid in the corresponding flow interval to form alternating vortex columns. The frequency of these vortex columns is proportional to the average flow velocity in the pipeline, has regularity and asymmetry, and the number appears in pairs, and the rotation direction of the vortices on both sides is opposite.

The vortex flowmeter uses a detecting device to measure the vortex's frequency in order to compute the fluid's flow rate. By expressing these parameters through the average flow velocity, the frequency of vortex generation, and the frontal width of the vortex generator, the formula can be obtained: f=Sr×v/d. Among them, Sr represents the Reynolds number function, and its value varies according to the properties of the fluid. Vortex flowmeters can measure the flow rate in various single-phase fluid environments, including positive gas flow, liquid flow, and gas flow. The fluid must exist in a single phase in order to guarantee measurement accuracy, as the presence of a mixed phase fluid will compromise measurement accuracy.


The straight pipe section's criteria are essential for installing the vortex flowmeter. Different types of flowmeters have different requirements for the straight pipe section, but most require the length of the straight pipe section to be between 5 and 3 times the corresponding pipe diameter. The length of the straight pipe section is crucial to the measurement accuracy and stability of the flowmeter. For vortex flowmeters, 20D in front and 5D in the back is a more appropriate length requirement. The quality of the straight pipe section is crucial to the normal operation and accurate measurement of the flowmeter, so in engineering practice, it must be constructed in strict accordance with the design requirements.

In industrial production, a good flowmeter needs to be combined with a good on-site environment to play its due role. If the installation conditions are limited, it may lead to inaccurate measurements, thus affecting production efficiency. Therefore, when selecting and using a flow meter, it is necessary to fully consider the actual situation to ensure the normal operation and accurate measurement of the flow meter.