『Standard condition of vortex flowmeter』Related information(flow rotameter|digital flow meter|balo meter|hydraulic flow meter|volumetric meter|positive displacement meter|pitot tube flow meter|displacement meter|cfm meter|variable area flow meter|inline flow meter|differential pressure flow meter|calibrated flow meter|velocity meter|paddle wheel flow meter|oval gear flow meter|anemometer hvac|multiphase flow meter|doppler flow meter|thorpe tube flowmeter|heat flow meter)
1. What is a vortex flowmeter? What are the characteristics?
When a triangular cylindrical vortex generator is set up in a fluid, regular vortices are alternately generated from both sides of the vortex generator, which are called Karman vortices. The vortex columns are asymmetrically arranged downstream of the vortex generator.. A vortex flow meter is a volumetric flow meter that measures the volumetric flow rate, volumetric flow rate or mass flow rate of gases, vapors or liquids based on the K á rm á n Vortex Street principle. And it can be used as a flow transmitter in automation control systems. The vortex flowmeter measures flow rate using the principle of fluid oscillation. When the fluid passes through the vortex flowmeter in the pipeline, two columns of vortices proportional to the flow velocity alternate up and down behind the vortex generator in the triangular column. The release frequency of the vortices is related to the average velocity of the fluid flowing through the vortex generator and the characteristic width of the vortex generator. It can be expressed as follows: where is the release frequency of the vortices, in Hz; v is the average velocity of the fluid flowing through the vortex generator, in m/s; D is the characteristic width of the vortex generator, measured in meters; St is the Strouhal number, dimensionless, with a numerical range of 0.14-0.27.
2. Pipeline flowmeter
3. Working principle of vortex flowmeter | Manufacturer interpretation
Vortex flowmeter is a flow measurement instrument designed based on the Karman vortex principle, mainly used for flow detection of gases, liquids, and steam in industrial pipelines.
. The core principle and working proce_600x400.jpg)
1. Core principle: Karman vortex street effect. When the fluid flows through a non streamlined vortex generator (such as a triangular column), two regular vortices will alternately separate on both sides of the generator, forming Karman vortex streets. The release frequency (f) of the vortex is related to the fluid flow velocity (v) and the characteristic width of the generating body (d) as follows: f=Sr × (v/d), where Sr (Strouhal number) is a dimensionless constant that remains stable within a specific Reynolds number range (usually 2 × 10 ^ -7 × 10 ^ -2), ensuring a linear relationship between frequency and flow velocity. Figure 1: Schematic diagram of alternating vortices generated by fluid around a triangular column
Analysis of working process: When the fluid flows through the triangular column, vortices are alternately formed on both sides of the generating body due to pressure difference, and the strength of the vortices is proportional to the flow velocity.
. Frequency detection uses piezoelectric sensors, thermal sensors, or ultrasonic sensors to detect pressure fluctuations or flow rate changes caused by vortex shedding, and converts them into electrical signals. The frequency (f) of the pulse signal output by the signal processing sensor is directly related to the flow rate (v), and the flow rate is calculated by the following steps: Flow rate calculation: Obtain the average flow rate of the fluid according to the formula v=(f × d)/Sr. Flow calculation: Combined with the cross-sectional area of the pipeline (A), the volumetric flow rate Q=v × A; if mass flow rate is required, it needs to be multiplied by the fluid density (ρ), that is, M=Q × ρ. Figure 2: Logical process from v
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