By mean of narrow-beam transducers, the UVP system releases ultrasound pulses in the studied liquid, which are reflected by flowing particles, solid or gas. Comparing the emitted and received acoustic signals, shifted in frequency due to the Doppler effect, the liquid velocity can by evaluated at various distances on the transducer measuring axis.
The instruments using this technique, Ultrasonic Velocity Profilers (UVP), can be seen as a kind of sonar combined with speed camera techniques.
Each connected transducer measures a 1D velocity profile on its own axis. A combination of several transducers provides 2D or 3D maps of the studied flow, controlled and synchronized by one single UVP instrument.
As ultrasound travels in most liquids, both transparent and opaque liquid flows can be measured.
