FIXED TYPE DOPPLER ULTRASONIC OPEN CHANNEL FLOWMETER
Doppler Effect Ultrasonic Flowmeter uses reflected ultrasonic sound signals to measure fluid velocity. By gauging the frequency shift between the ultrasonic frequency source, the receiver and the fluid carrier, the relative motion is estimated. The resulting frequency shift is called the Doppler Effect.
The fluid velocity can be expressed as:
V = c (fr - ft) / 2 ft cosΦ (1) Fr = received frequency
Ft = transmission frequency
V = fluid flow rate
Φ = Relative angle between the transmitted ultrasonic beam and the fluid flow
C = speed of sound in liquid This method requires some of the reflective particles in the liquid.
The method is not suitable for clear liquids.
Advantages of Doppler Ultrasonic
Flowmeter Doppler counters can be used when other counters are not working. These liquid slurries can be gaseous liquids or some small or large amount of liquid on suspended solids.
The advantages can be summarized as follows:
➢ Less blocking flow ➢ Can be installed outside of pipes
➢ The pressure drop is equal to the equivalent length of a straight pipe
➢ Corrosion resistant ➢ Low power consumption
➢ They measure the flow of fluid in partially filled pipes and open channels.
➢ Does not require a sluice.
➢ Shows speed, level, instantaneous and total flow.
➢ Output signals, 4-20mA, RS485 (Modbus) /GPRS
➢ Optional ,16GB SD card
➢ 20 coordinate points can be determined.
INSTALLED PIPE APPLICATIONS
Limitations of Doppler Ultrasonic Flowmeters Doppler flowmeter performance is dependent on the physical properties of the liquid, such as sonic conductivity, particle density, and flow profile.
The unevenness of the particle distribution in the pipe section can be miscalculated, resulting in an average velocity. Flowmeter accuracy is sensitive to velocity profile variations and the distribution of acoustic reflectors in the measuring section.
Unlike other acoustic flow meters, Doppler meters are affected by changes in the sonic velocity of the fluid. As a result, the meter is also sensitive to density and temperature changes. These problems are not suitable for applications with Doppler flow meters.
