Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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Dual-Plane Ultrasound Flow Measurements in Liquid Metals

Büttner, L.; Nauber, R.; Burger, M.; Räbiger, D.; Franke, S.; Eckert, S.; Czarske, J.

An ultrasound measurement system for dual-plane, two-component flow velocity measure-ments especially in opaque liquids is presented.
Present-day techniques for measuring local flow structures in opaque liquids disclose consid-erable drawbacks concerning a line-wise measurement of single ultrasound probes. For study-ing time-varying flow patterns, conventional ultrasound techniques are either limited by a time-consuming mechanical traversing or by the sequential operation of single probes.
The measurement system presented within this paper employs 4 transducer arrays with a total of 100 single elements which allows for a flow-mapping without mechanical traversing. A high frame rate of several 10 Hz has been achieved due to an efficient parallelization scheme using time division multiplex realized by a microcontroller-controlled electronic switching matrix.
The functionality and capability of the measurement system is demonstrated at a liquid metal flow at room temperature inside a cube driven by a rotating magnetic field (RMF). For the first time, the primary and the secondary flow have been studied in detail and simultaneously using a configuration with two crossed measurement planes. The experimental data confirm predictions made by numeric simulation. After a sudden switching on of the RMF inertial oscillations of the secondary flow were observed by means of a time-resolved measurement with a frame rate of 3.4 Hz.
The experiments demonstrate that the presented measurement system is able to investigate complex and transient flow structures in opaque liquids. Due to its ability to study the tem-poral evolution of local flow structures, the measurement system could provide a considerable progress for fluid dynamics research, in particular for applications in the food industry or liq-uid metal technologies.

Keywords: ultrasound Doppler method; ultrasound sensor arrays; flow measurements; liquid metal flow; magnetohydrodynamics

Publ.-Id: 18086