Flow meters gauge the speed of flowing fluids within a channel with volume or mass. Many flow meters have moving parts. However, fluid traits can cause problems with the moving parts. For instance, silt and debris can cause the moving parts to stall. A case like that would need a meter without moving parts like a vortex flow meter.
You can use a vortex flowmeter for all fluid uses. However, the most common use is steam flow gauging. The knowledge of how flow meters work helps you when choosing a flow meter. It ensures you select the right tool for your firm. In addition, you can assess your fluid traits and have an idea if you need a vortex flow meter or not.
Vortex Flow Meter History
Leonardo da Vinci drafted eddies that form downstream of an object in 1953. However, it was hard to explain since it was a new principle. In 1878, Czech Vincenc Strauhal created a figure to explain how eddies form after a fluid encounter with a bluff body. However, this principle was described as a vibration of a stretched wire exposed in an air jet. Therefore, the frequency of the pulse would directly relate to the speed of air.
Theodore von Karman applied this principle to explain flow measurement. He explained the concept well in 1912. Karman explained the effect of a non-streamlined body on a stream of flowing fluids. The bluff body causes the fluid to separate alternately on different sides.
Working Principle of Vortex Flow Meter
A vortex flow meter must have a bluff body to disrupt the flow. However, the bluff body should not block the flow of fluids within the channel. The bluff body is located before a measuring sensor.
As the fluid flows downstream, it hits the bluff body and creates eddies downstream. The eddies from both sides have a uniform frequency. This is because the frequency of the eddies is directly related to the velocity of the fluid. But the meter is not sensitive to speed, heat, and pressure. However, the rate of the fluid needs to beat the minimum Raynolds number to create an eddy current.
There are different bluff body types used to create eddy currents downstream. Some shapes offer less pressure loss, making them more desirable than others; The bluff body types include rod, plate, wedge, and gutter.
When the fluid hits the bluff body, it splits into different directions. At the end of the body, the fluid curls to fill the gap. At that point, it forms an eddy that moves downstream. The frequency of the eddies is quick if the velocity of the fluid is high. The frequency will reduce once the velocity of the fluid drops.
Vortex flow meter would not work well with highly viscous fluids. It’s because viscosity strips off the ability of the fluid to flow first. Thus, it does not hit the Reynolds number to create eddy currents.
What Influences the Performance of Vortex Flow Meters?
Like any other flow meter, a vortex flow meter needs frequent maintenance. You will appreciate this fact when you know that age of the meter affects the performance. Over time, the shedder bar loses its geometry to erosion. Also, it can accumulate deposit die to corrosion of piping upstream.
If you fail to secure the cheddar bar, it can change position, thus affecting the efficiency of the meter., Hydraulic noise is also a factor that changes the efficiency of the meter.
Some meter sizings are unfit for a vortex flow meter. Always strive to work within the ranges of 12 mm and 300 mm diameters.
Conclusion
The vortex flow meter principle is simple. It involves introducing a bluff body within a flow channel. The body breaks the smooth flow of the fluid, creating vortices downstream. The meter’s sensor counts the frequency of the vortices that directly relate to the fluid velocity.
