Vortex flowmeter pulse

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1. Actual flow rate of vortex flowmeter

The flow formula measured by vortex flowmeter is qv=π D2U/4=π D2mdf/4Sr K=f/qv=[π D2md/4Sr] -1. Under specific flow conditions, a part of the fluid kinetic energy is converted into fluid vibration, and the vibration frequency of the vortex flowmeter is proportional to the flow rate (flow rate). A flowmeter that works based on this principle is called a fluid vibration flowmeter. At present, there are three types of fluid vibration flow meters: vortex street flow meters, vortex precession flow meters, and jet flow meters. Fluid vibration flowmeter has the following characteristics: 1) The output is a pulse frequency, which is proportional to the actual volumetric flow rate of the measured fluid and is not affected by fluid composition, density, pressure, or temperature; 2) The measurement range is wide, and the general range can reach 10:1 or more; 3) The accuracy is above average level; 4) No movable parts, high reliability; 5) The structure is simple and sturdy, easy to install, and has low maintenance costs; 6) Widely applicable, suitable for liquids, gases, and vapors. The working principle is to set up a vortex generator (blocking fluid) in the fluid, and generate regular vortices alternately from both sides of the vortex generator. This type of vortex is called a Karman vortex street, as shown in Figure 1. The vortices are arranged asymmetrically downstream of the vortex generator. Assuming the frequency of vortex occurrence is f, the average velocity of the measured medium flow is U, the width of the vortex generator face is d, and the diameter of the body is D. According to the principle of Karman vortex street, there is a relationship f=SrU1/d=SrU/md. The vortex

generator is the main component of the detector, which is closely related to the flow characteristics (instrument coefficient, linearity, range, etc.) and resistance characteristics (pressure loss) of the instrument. It is required that: 1) the vortex can be controlled to separate synchronously in the axial direction of the vortex generator; 2) Within a wide range of Reynolds numbers, there are stable vortex separation points, and maintaining a constant branch state results in the Strouhal number; 3) Can generate strong vortex streets, with a high signal-to-noise ratio of the signal; 4) The shape and structure are simple, easy to process and standardize geometric parameters, as well as the installation and combination of various detection components; 5) The material should meet the requirements of fluid properties, be corrosion-resistant, wear-resistant, and resistant to temperature changes; 6) The natural frequency is outside the frequency band of the vortex signal.

2. Flow Calculation of Vortex Flow Meter

The flow calculation of vortex flow meter is mainly achieved through the following steps and formulas: Measuring the frequency of vortex occurrence: The vortex flow meter first measures the frequency of vortex occurrence, which is directly related to the average flow velocity of the measured medium.

. The formula for calculating frequency is: f=Sr * U1/d=Sr * U/m, where Sr is the Strouhal number, reflecting the strength of the vortex; U1 is the average flow velocity on both sides of the vortex generator; D is the width of the upstream face of the vortex generator; M is the ratio of the bow shaped area on both sides of the vortex generator to the cross-sectional area of the pipeline. Calculate volumet

1. Actual flow rate of vortex flowmeter

2. Flow Calculation of Vortex Flow Meter

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