Coefficient of vortex flowmeter

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1. Working principle of steam vortex flowmeter

The steam vortex flowmeter is based on the Karman vortex principle, which measures the flow rate by detecting the frequency of vortex generation in the fluid. Its core working principle and key points are as follows

1. Generation and characteristics of Karman vortex. Vortex generator: A triangular cylindrical (or cylindrical) vortex generator is installed in the fluid pipeline, and regular vortices are alternately generated on both sides when the fluid flows through, which is called Karman vortex.

. Vortex arrangement: The vortex arrangement is asymmetrically arranged downstream of the generating body, and its frequency f is related to the fluid velocity and geometric dimensions of the generating body. 2. Mathematical relationship between flow rate and frequency. The basic formula for the relationship between vortex frequency f and the average fluid velocity U is: f=Sr · U? /d = Sr·U/(m·d)U? Average velocity on both sides of the vortex generator (m/s); Sr: Strouhal number (dimensionless, related to the shape of the generator and Reynolds number); d: The width of the inflow surface of the body; m: The ratio of the area of the arch on both sides of the body to the cross-sectional area of the pipeline. Volume flow calculation: The volume flow rate q in the pipeline is q?=(π D2/4) · U=(π D2 · m · d · f)/(4 · Sr) D: the inner diameter of the pipeline. Instrument coefficient K: K=f/q? = [πD2·m·d/(4·Sr)]? 1K is the pulse number/m3 (P/m3), which is only related to the generator, pipeline size, and Sr. At Reynolds number ReD=2 × 10? ~7×10? Within the range, Sr can be regarded as a constant to ensure the stability of the instrument. When measuring gas, the effects Coefficient of vortex flowmeter

of pressure, temperature, and compression coefficient need to be considered. The conversion formula for volumetric sliding flow rate between standard state (0 ℃ or 20 ℃, 101.325kPa) and operating conditions is: q??=q? ·(P/P?)·(T?/T)·(Z/Z?)q?? 、 Q?: Volume flow rate under standard and operating conditions (m3/h); P?, P: Absolute pressure under standard and operating conditions (Pa); T?, T: thermodynamic temperature under standard and operating conditions (K); Z? Z: Gas compression coefficient under standard and operating conditions. Advantages: The pulse frequency signal output by VSF is not affected by changes in fluid properties (such as density and viscosity), and the instrument coefficient is only related to geometric dimensions within a specific Reynolds number range. However, mass flow measurement requires synchronous monitoring of volumetric flow rate and density. 4. Adaptability of steam vortex flowmeter. Medium compatibility: It can directly measure the operating volume flow rate of steam, air, gas, water, and liquid without temperature and pressure compensation. Extension function: Temperature and pressure compensation type: equipped with temperature and pressure sensors, can calculate standard condition volume flow rate and mass flow rate (such as the mass flow rate of saturated steam is calculated based on temperature to determine pressure). Battery powered type: using low-power technology, lithium battery powered can operate for more than one year, displaying instantaneous/cumulative flow locally, saving installation costs

5. Optimization technology for variable diameter measurement habit problem: The actual flow range often deviates from the optimal working section of the instrument (maximum flow belo

1. Working principle of steam vortex flowmeter

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