『The principle of vortex flowmeter』Related information(clamp on meter|electromagnetic meter|venturi meterrotameter|orifice meter|ultrasonic flow meter|mass flow meter|coriolis mass flow meter|coriolis flow meter|magnetic flow meter|magmeter flow meter|magflow flow meter|mag meter flow meter|electromagnetic flow meter|vortex flow meter|turbine flow meter|thermal mass flow meter|thermal flow meter|rotameter flow meter)
What is the working principle of a vortex flowmeter that must be learned for beginners in instrumentation?
The vortex flowmeter is a fluid natural oscillation instrument developed based on the principle of "Karman vortex street". Its core is to calculate the flow rate by detecting the vortex frequency generated by the fluid when it bypasses obstacles.. The following is a detailed explanation of its working principle.
1. Definition of Karman vortex street phenomenon: When a fluid (gas or liquid) passes around a non streamlined obstacle (such as a triangular column or cylinder), two columns of vortices are alternately generated on both sides downstream of the obstacle. The arrangement of vortices is similar to the street lights on both sides of the street, hence it is called "vortex street". Discoverer: This phenomenon was mathematically derived and experimentally verified by aerospace engineer von Karman, hence it is also known as the "Karman vortex street". Key characteristics: The frequency of vortex generation (f) is linearly related to the fluid flow velocity (v) under specific conditions, that is, the higher the flow velocity, the faster the frequency of vortex shedding
2. Working principle and structural composition of vortex flowmeter: Non streamlined vortex generator: vertically inserted into the pipeline, forcing the fluid to generate vortex streets. Sensors: detect vortex frequency, common types include piezoelectric, strain gauge, hot wire, etc. Signal processing unit: converts sensor signals into flow readings. Working process: Fluid flow: When the fluid flows through the vortex generator, vortices are alternately generated on both sides of the generator. Vortex shedding: Vortex sh
3. Core formula and parameter Strauhal number (St): a dimensionless number describing the relationship between vortex shedding frequency and flow velocity, with the formula [St=frac {f cdot d} {v}], where d is the characteristic width of the generator and v is the fluid flow velocity. Within a certain range of Reynolds number (Re) (usually 2 × 10 ^ -7 × 10 ^ -2), St is a constant, and f is linearly related to v. Flow formula derivation: Combined with the cross-sectional area A of the pipeline, the volumetric flow rate Q can be expressed as: [Q=frac {f cdot A} {St cdot d} cdot d=frac {f cdot A} {K}], where K is the instrument constant that needs to be determined through calibration
4. Technical advantages and application scenario advantages: no mechanical components, low maintenance, long service life. Wide measurement range: The range ratio can reach 10:1~20:1. Low pressure loss and sliding: suitable for low-pressure systems. Strong anti-interference ability: Contemporary vortex flowmeters (such as the LUB series) can suppress 1.5g omnidirectional vibration interference through patented technologies (such as automatic tracking filtering and vibration interferen
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