Flow measurements in continuous casting models by means of contactless inductive flow tomography under the influence of electromagnetic brakes

Most of the steel in the world is produced by continuous casting, where liquid metal flows from a tundish through a submerged entry nozzle into a copper mould. The mould is cooled by water, so a solid shell starts to form at the mould walls. The resulting steel strand is pulled out of the mould continuously and solidifies completely.
In industry it is well-known that an unstable flow in the mould has negative effects on the resulting steel’s quality. Electromagnetic brakes (EMBr) are expected to dampen instabilities, although their impact on the flow can hardly be examined directly in liquid steel. In spite of the casting method’s economical and industrial importance, only a few simple measurement techniques are available to investigate the actual flow patterns in the mould. A more sophisticated technique for liquid metal flow measurements could help to resolve the open issues in the mould flow.
The contactless inductive flow tomography (CIFT) is a technique that measures the mean global flow of an electrically conducting melt by exposing it to a magnetic excitation field and measuring the flow induced perturbations of that field outside the melt. The velocity profile can then be calculated by solving an inverse problem, using adequate regularization techniques to deal with the non-uniqueness.
We present preliminary results for a physical model of a mould with a rectangular cross-section of 140 × 35 mm 2 in the presence of an EMBr. Additionally we show flow reconstructions for a 400 × 100 mm 2 mould, demonstrating the upward scalability of CIFT.