?What is a Vortex Flowmeter
In the previous article, the types of flowmeters and how they work were briefly described. .
Application: Vortex flowmeters can calculate the flow of steam, gas and liquid using vortex generation. Vortex flow occurs when there is an obstacle in the fluid flow path. The word obstruction here refers to a body that is resistant to the path of a fluid that causes a rotational motion to form in its downstream path.
When the vortices are formed and flow, a change is made in the pressure created. This pressure change is used to operate a sensor at a frequency proportional to the eddy current. In continuous fluid flow, a series of vortices generate electrical pulses at a frequency commensurate with the velocity of the fluid. The obtained velocity can be converted to volumetric flow rate. The output of a vortex flow meter is dependent on a factor of k. The factor k indicates the frequency of the vortices produced at the velocity of the fluid.
Fluid velocity = Vortex Frequency / k-factor
The factor k changes with the Reynolds number (a non-unit quantity that indicates the ratio of inertial force to inertial force). Although practically constant in a wide range of Dubai. If eddy flow meters operate in the flat range, the flow rate is linearly related to velocity.
Vortex Flowmeter (Vortex Flowmeter)
If the ball is placed in the path of a pipe containing fluid flow, a boundary layer is formed that extends to the surface of the ball body. Due to insufficient motion size and reverse pressure gradient, separation occurs and an unstable shear layer is created. This cut layer turns into vortices that start to spread from the side of the ball. The frequency at which the vortex pair flows is proportional to the velocity of the fluid. Since the creation process. Vortex flows are repetitive, this method can be used to determine the flow.
Sensors are used to detect the flow of vortex pairs, that is, to convert changes in pressure and velocity caused by vortices into electrical signals.
The number st, strouhal, the frequency of production of vortex pairs (f), the specified dimensions of the ball barrier, d, and the velocity of the fluid are related.
U = (f * d) / st
The st number is usually independent of density, pressure, zinc and other physical parameters. In such a situation, the flow rate is directly proportional to the flow frequency of the vortex pair. That is, the rate of vortex pulses is:
U = ξ * f
where in :
d / st is constant equal to: ξ
And the volumetric flow rate in such a situation is expressed by the following relation:
Qv = A * U = [(A * d) / st] * f
The K factor for the eddy flow meter is proportional to the strouhal number.
K = st / [A * d] = f / qv
qv = f / k
If the fluid density at temperature and operating pressure is known, the mass flow can be obtained from the following equation:
qm = ρf * f / k
The following figures show the wind barriers (square, rectangular, T-shaped, trapezoidal).
How to install a whirlpool flow meter is shown in the figure below.