Application of ultrasonic Doppler velocimetry to high temperature liquid is today limited by some technological aspects, like the availability of high temperature ultrasonic transducers, but by also some physical aspects, like crossing wall, influences of high temperature gradient, injection of US energy into the analysed medium, type and sizes of ultrasonic reflectors. A good knowledge of the ultrasonic field is also an important aspect.

In order to profit from the main advantage of pulsed ultrasonic Doppler velocimetry, which is a depth resolution, it is of utmost importance to have a good understanding of these physical limitation. The aim of my talk is not to give solution to these problems, but to point out some of the challenges that have to be solved in order to apply high temperature ultrasonic Doppler velocimetry to real industrial applications.