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Phased Array Ultrasound System for Planar Flow Mapping in Liquid Metals
Mäder, K.; Nauber, R.; Galindo, V.ORC; Beyer, H.; Büttner, L.; Eckert, S.; Czarske, J.
Research in magnetohydrodynamics (MHD) aims at a better understanding of the interaction of conductive fluids and time-varying magnetic fields. Controllable magnetic fields can be used to optimize flows in technical and industrial processes involving liquid metals in order to improve quality and yield. However, necessary experimental studies for the investigations on physical models at room temperature are often limited by the performance of flow instrumentation for opaque liquids. With the phased array ultrasound Doppler velocimeter (PAUDV) we present a modular research platform for flow mapping in liquid metals. It consists of a modular electronics unit capable to interface ultrasound arrays with up to 256 channels. Each channel can be individually configured regarding the excitation pattern (three-level quantization, 64 samples) and the delay (1.6 ns resolution). With the individual addressing of channels the phased array technique to dynamically focus the ultrasound beam can be employed. This allows to resolve smaller flow structures in planar measurements compared to fixed-beam sensors. In addition, it enables the use of receive beamforming and plane wave transmission, which allows to significantly increase the time resolution and to perform 2d flow mapping with only one acoustical access via the cross beam technique. Fast electrical traversing of the measurement volume allows to obtain and visualize turbulence statistics. The capabilities of this research platform are demonstrated on measurements in the alloy gallium-indium-tin at room temperature. 2d velocity measurements of a flow in a cubic vessel influenced by a rotating magnetic field (RMF) are shown and compared to results of a semi-analytical simulation. Furthermore, two-point correlation functions of the velocity field for different magnitudes of the RMF are presented and discussed.
Keywords: Ultrasound Velocimeter, Liquid Metals,. Rotating Magnetic Fields

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Publ.-Id: 24498 - Permalink