The working principle of vortex flowmeter: if a triangular column vortex generator is set in the fluid, regular vortices are generated alternately from both sides of the vortex generator. This kind of vortex is called Carmen vortex, the vortex column is asymmetrically arranged downstream of the vortex generator.
Vortex flowmeter is based on Carmen vortex street principle (
K á rm á n Vortex Street)
A volume flowmeter that measures the volume flow of gas, steam or liquid, the volume flow of standard conditions or the mass flow.
It can be used as a flow transmitter in an automatic control system.
Vortex flowmeter uses the principle of fluid oscillation to measure flow. When the fluid passes through the vortex flow transmitter in the pipeline, two rows of vortices proportional to the flow rate are alternately generated up and down behind the vortex generator of the triangular column, the release frequency of the vortex is related to the average velocity of the fluid flowing through the vortex generator and the characteristic width of the vortex generator, which can be expressed by the following formula: in the formula: the release frequency of the vortex, and the unit is Hz;
V is the average velocity of the fluid flowing through the vortex generator, and the unit is m/s;
D is the characteristic width of vortex generator, and the unit is m; St is strauhar number (Strouhal number), Dimensionless, its numerical range is 0. 14-0. 27, St is a function of Reynolds number.
When Reynolds number Re is within the range, St value is about 0. 2.
In the measurement, the Reynolds number of the fluid should be satisfied as much as possible, at which time the vortex frequency.
Therefore, the average velocity v of the fluid flowing through the vortex generator can be calculated by measuring the vortex frequency, and then the flow q can be obtained by the formula, where A is the cross-sectional area of the fluid flowing through the vortex generator.
Vortex flowmeter is a kind of flowmeter designed and manufactured by applying Carmen vortex principle and modern electronic technology. The frequency of vortex occurrence is proportional to the speed of fluid. Under certain conditions, it conforms to the following formula :(
Where f: Vortex occurrence frequency v: flow rate d: Triangle column width St: strauha number)
The fluid vortex generates alternating pressure on the triangular column, which is detected by the piezoelectric signal sensor and amplified by the preamplifier to become a standard electrical signal output.
VA series vortex flowmeter can be used for a wide range of gases (Including steam)
Volume measurement with liquid, and mass calculation and various parameter display can be carried out with flow totalizer and temperature and pressure sensors.