Vortex Flowmeter Information
What is Vortex Flowmeter
A vortex flowmeter is a volumetric flowmeter that operates based on the Karman Vortex Street principle. It is used to measure the volumetric flow, standard volumetric flow, or mass flow of gases, vapors, or liquids. It consists of a vortex generator, a sensor, and a signal processing unit. The vortex generator is used to generate vortices in the fluid, the sensor is used to detect the vortices, and the signal processing unit is used to process the detected signals and calculate the flow rate.
History of Vortex Flowmeter
The concept of the Karman Vortex Street was first proposed by Hungarian-American mathematician and aerodynamicist Theodore von Kármán in the 1910s. In the 1960s, scientists began to apply this principle to the measurement of fluid flow, and the first vortex flowmeter was developed. Since then, with the continuous development of technology, vortex flowmeters have been continuously improved and refined, and their accuracy, reliability, and application range have been continuously expanded.
Purpose of Vortex Flowmeter
Vortex flowmeters are mainly used for measuring the flow rate of fluids in industrial pipelines, such as gases, liquids, and vapors. They are widely used in various industries, including petroleum and natural gas, chemical, power, metallurgy, and water treatment. In these industries, vortex flowmeters are used to monitor and control the flow rate of fluids, ensure the efficient and safe operation of production processes, and achieve accurate measurement and management of materials and energy.
Principle of Vortex Flowmeter
In the fluid, a triangular prism-shaped vortex generator is set up. Then, regular vortices are alternately generated on both sides of the vortex generator. These vortices are called Karman vortices, and the vortex rows are arranged asymmetrically downstream of the vortex generator. The frequency of vortex shedding is directly proportional to the average velocity of the fluid flowing through the vortex generator and is related to the characteristic width of the vortex generator. By measuring the frequency of vortex shedding, the average velocity of the fluid can be calculated, and then the flow rate can be obtained. The specific formula is: (f = St times frac{v}{d}), where (f) is the frequency of vortex shedding, (v) is the average velocity of the fluid, (d) is the characteristic width of the vortex generator, and (St) is the Strouhal number, which is dimensionless and has a value range of 0.14-0.27.
Features of Vortex Flowmeter
- High accuracy: It has little influence from parameters such as fluid density, pressure, temperature, and viscosity when measuring the volumetric flow under working conditions, thus achieving high measurement accuracy.
- Wide measurement range: The rangeability is large, generally reaching 1:10, and it can adapt to different flow ranges, from extremely low to extremely high flows.
- Strong anti-interference ability: It is insensitive to impurities and bubbles in the fluid and can work stably in harsh industrial environments.
- Low maintenance requirements: Due to its simple structure and no moving parts, the maintenance cost is relatively low.
- Small pressure loss: The pressure loss caused is small, resulting in low operating costs and greater energy-saving significance.
- Diverse output signals: It has analog standard signals (such as 4-20 mA, 0-10 V, etc.) and digital pulse signals, which can be easily used with digital systems such as computers.
Types of Vortex Flowmeter
- According to the connection method: It can be divided into flange type, flange clamping type, and insertion type.
- According to the purpose: It can be divided into explosion-proof type, ordinary type, high-temperature type, corrosion-resistant type, and insertion type.
- According to the structure: It can be divided into integral type and remote transmission type.
- According to the measurement principle: It can be divided into volume flow type and mass flow type.
- According to the function: It can be divided into conventional type and intelligent type.
- According to the detection method: It can be divided into thermal sensitive type, ultrasonic type, capacitive type, stress type, strain type, vibrating body type, photoelectric type, optical fiber type, and electromagnetic type.
Precautions for using Vortex Flowmeter
- Installation location: The flowmeter should be installed in a straight pipe section with sufficient upstream and downstream straight pipe lengths. The upstream straight pipe length is generally 15-20 times the pipe diameter, and the downstream straight pipe length is 5-10 times the pipe diameter.
