Résumé des résultats (Abstract)
(Anglais)
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Flows of metallic melts or semiconductors play an important role in a number of industrial branches like metallurgy or crystal growth technology. However, the instrumentation of high temperature liquid metal flows has to be considered as very difficult. The objective of this project is to extent the applicability of the Ultrasonic Doppler technique to velocity measurements in high temperature liquid metal flows.
To apply the Ultrasonic Doppler Velocimetry in high temperature metallic melts the thermal restriction of the ultrasonic transducers has to be overcome. Therefore, a concept has been developed to couple the ultrasonic transducer with an acoustic wave guide. To realise this concept, a couple of problems have to be solved, like acoustic coupling between ultrasonic transducer and wave guide, transmission of the ultrasound through the wave guide, wetting between the metallic melt and the wave guide, or allocation of reflecting particles in the melt. Therefore, experiments have been performed to investigate such generic questions being typical for the application of ultrasonic diagnostic methods to high temperature liquid metal flows. Several metals and alloys characterised by different melting points and material properties have been used, for instance, sodium, gallium, eutectic InGaSn and PbBi, respectively.
In the first period of the project material tests in liquid steel and aluminium, respectively, have been done to choose the candidates for the acoustic wave guide used at the corresponding high temperature application. Several variants for an integrated system consisting of the transducer, the wave-guide and the DOP2000 system have been developed and tested. Further tests are going on in order to increase the reliability of that system and to extend the range of applicable temperatures and metallic melts.
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