Vortex flow meter is a type of flow meter that uses the principle of the von Kármán effect to measure the flow of fluid, usually a gas or a liquid, through a pipe. The von Kármán effect is the phenomenon that occurs when a fluid flows past a bluff body, such as a cylinder or a sphere, causing vortices to form alternately on either side of the body. The frequency of these vortices is proportional to the velocity of the fluid.
Vortex flow meters consist of a bluff body, often in the shape of a shedder bar or a bluff cone, placed in the flow path of the fluid. As the fluid flows past the bluff body, it creates vortices, which are detected by a sensor, typically a piezoelectric crystal or a pressure sensor, placed downstream from the bluff body. The frequency of the vortices is then used to calculate the flow rate of the fluid.
The advantages of vortex flow meters over other flow measurement technologies include high accuracy, suitability for a wide range of fluids, low maintenance requirements, long lifespan, lower pressure drop compared to other meters, and resistance to wear and tear. Vortex flow meters are also less susceptible to fluid density and viscosity changes, making them suitable for measuring gases and liquids. Additionally, vortex flow meters can be used in applications where other flow measurement technologies, such as in high-temperature or high-pressure environments, may need to be more practical and possible.
How Vortex Flow Meters Work
Vortex flow meter technology is widely used for measuring the flow of liquids, gases, and steam in various industries. It works based on the principle that when fluid flows past an obstruction in a pipe, it creates a series of vortices in the downstream flow. The frequency of these vortices is proportional to the fluid flow rate, allowing the vortex flow meter to measure the fluid flow rate accurately.
The main components of a vortex flow meter include a bluff body or shedder bar, a piezoelectric crystal sensor, and a signal processing unit. The bluff body or shedder bar is a small cylindrical structure placed in the fluid flow path. The fluid flows past the bluff body, creating a series of vortices that alternate from side to side. The piezoelectric crystal sensor is placed behind the bluff body and detects the pressure fluctuations caused by the vortices. The signal processing unit processes the sensor signals and calculates the fluid flow rate based on the frequency of the vortices.
To measure flow, the vortex flow meter calculates the frequency of the vortices created by the fluid flow. The piezoelectric crystal sensor detects the pressure fluctuations caused by the vortices and sends the signals to the signal processing unit. The signal processing unit calculates the frequency of the vortices and converts it into a flow rate based on the fluid density and the pipe size. The vortex flow meter is calibrated for each application to ensure accurate flow measurement.
Advantages of Vortex Flow Meters
- High accuracy: Vortex flow meters are known for their high accuracy and repeatability. They can measure fluid flow with an accuracy of up to +/- 1% of the actual flow rate, making them a reliable option for critical applications.
- Wide range of fluids: Vortex flow meters can measure the flow of various fluids, including gases, liquids, and steam. They can also handle high-viscosity fluids and slurries, making them a versatile option for many industries.
- Low maintenance requirements: Vortex flow meters are relatively simple devices with few moving parts, making them easy to maintain. They also do not require frequent calibration, which reduces the need for maintenance.
- Long lifespan: Vortex flow meters have a longer lifespan than other flow measurement technologies due to their simple design and low maintenance requirements.
- Lower pressure-drop: Vortex flow meters have a lower pressure drop than other flow meters, meaning they do not impede fluid flow as much. This makes them a more energy-efficient option for measuring flow.
- Resistant to wear and tear: Vortex flow meters are designed to withstand wear and tear, making them suitable for harsh environments. They are also resistant to corrosion and erosion, which can prolong their lifespan.
Comparison with other Flow Measurement Technologies
Vortex flow meters are commonly used flow measurement technologies that measure the frequency of vortices shed by a bluff body in a fluid flow. Here’s a comparison of vortex flow meters with other commonly used flow measurement technologies:
- Differential Pressure (DP) Flowmeters:
Pros: DP flowmeters are relatively simple and inexpensive and can be used for various fluids and flow rates.
Cons: They can be sensitive to changes in fluid properties such as temperature and density and require regular maintenance to ensure accuracy. DP flowmeters can also cause pressure drops, leading to energy losses in the system.
Pros: Electromagnetic flowmeters are highly accurate and can measure velocities and conductivities.
Cons: They are relatively expensive, require a conductive fluid, and can be affected by external magnetic fields.
Pros: Coriolis flowmeters are highly accurate and can measure mass flow directly. Changes in fluid properties such as temperature and density do not affect them.
Cons: They are relatively expensive and have limited rangeability.
Pros: Ultrasonic flowmeters are non-intrusive, can measure a wide range of fluids, and have no pressure drop.
Cons: They can be affected by changes in fluid properties such as temperature and viscosity and may require periodic calibration.
Pros: Vortex flowmeters have no moving parts, are not affected by changes in fluid properties, and can measure a wide range of fluids and flow rates.
Cons: They may not be as accurate as other flow measurement technologies, particularly at low flow rates. Vortex flowmeters may also require a relatively high Reynolds number to function correctly and can be affected by vibrations and other disturbances in the flow.