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(Pulsed) Ultrasound Velocity Profiling (UVP)

Ultrasound Velocity Profiling (UVP) is a technique originally developed for studying blood flow in humans. This method was extended in the mid 1980’s to include measurements also in general fluids and has since become an important tool within research and fluid engineering.UVP is sometimes also called Pulsed Ultrasound Velocimentry (PUV) and it is a technique to measure an instantaneous velocity profile in a liquid flow by echography.

With Ultrasound Velocity Profiling (UVP), pulses of ultrasound are transmitted through the pipe where the liquid flows. When the ultrasound hits the fluid, or particles in the fluid, it is echoed back and the returning pulse is measured using a sensor. In this process, when the pulse is reflected by a scattering particle suspended in the fluid, the signal frequency is altered. In other words, there is a slight difference in frequency/time between the pulse sent out and the pulse coming back.

It is however important to note that the classical Doppler effect causing this is only an artefect in UVP systems. This small difference or shifts in positions between transmitted pulses can then be analyzed and related to the local fluid velocity.The measurement is unidimensional (1D) providing a velocity profile projected along the probing axis. Since the majority of the small scattering particles are assumed to travel at a velocity equal to that of the continuous phase the true velocity distribution along the probing axis is obtained.

Example of measured spectra (velocity distribution in pipe)

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Johan Wiklund