Mace HVFlo XCi, Руководство по эксплуатации продукта

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About Doppler Ultrasonics
MACE XCi devices utilise the Doppler Effect to measure velocity of stream flows.
The Doppler Effect (after C. J. Doppler 1803-53) is defined as, “the apparent change in the frequency of
sound or electromagnetic radiation due to relative motion between the source and the observer” (Uvarov &
Isaacs (1986). Dictionary of Science).
The MACE Doppler ultrasonic velocity sensors transmit an ultrasonic (sound) wave into the flow. This sound
wave is reflected by acoustically reflective particles (e.g. air bubbles, suspended solids) and the instrument
detects the reflected frequencies. The difference between the transmitted frequency and the received
frequencies is directly proportional to the velocity of the stream flow.
In full or partially full pipes, the velocity of the
stream flow varies markedly across the cross-
section of the pipe. Typically, velocity is zero
along the wall of the pipe and increases to a
maximum at or about the centre of the pipe.
MACE Doppler ultrasonic velocity sensors
receive reflected frequencies from particles
moving at these different velocities. The greater
the area of flow moving at a particular velocity,
the greater the number of reflections with the
respective frequency shift. The average velocity
of the stream is therefore calculated by
averaging those frequency reflections received
across the whole stream profile. In layman’s
terms a simple analogy for the way MACE
Doppler ultrasonics operate is that it’s similar to
“switching on a flash light in a fog”. Any reflective
particle that moves within the “beam” will be
seen by the ultrasonic sensor. MACE Doppler
ultrasonic velocity sensors provide a true
average stream velocity.
MACE XCi User Manual - 13 -