Lorentz force velocimetry (LFV) is a noncontact electromagnetic flow measurement technique for liquid metals that is currently used in fundamental research and metallurgy. Up to now, the application of LFV was limited to the narrow class of liquids whose electrical conductivity is of the order 106 S/m. Here, we demonstrate that LFV can be applied to liquids with conductivities up to six orders of magnitude smaller than in liquid metals. We further argue that this range can be extended to 10−3 S/m under industrial and to 10−6 S/m under laboratory conditions making LFV applicable to most liquids of practical interest.

We present a novel application of a contactless flow measurement system and validate its feasibility on an electrolyte pipe flow. The device relies on the technique of Lorentz force velocimetry (LFV). LFV operates without any contact to either the fluid or the surrounding pipe walls. This is advantageous if the fluid under consideration is hot and aggressive, like a glass melt for example. Glass melts, however, have a very low electrical conductivity, resulting in Lorentz forces in the micronewton range. In order to resolve these tiny forces, we developed a measurement system based on the principle of deflection. Experiments on an electrolyte flow with an electrical conductivity of less than 20 S m −1 prove to be successful and to agree well with numerical simulations, and therefore show for the first time the applicability of LFV for fluids of such low conductivities.

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Zusammenfassung Der Beitrag beschreibt den experimentellen Aufbau und die ersten Messergebnisse einer neuen Durchflussmesstechnik für schwach leitfähige Fluide mittels Lorentzkraft-Anemometrie, einem berührungslosen Messverfahren, welches schon erfolgreich für gut leitfähige Fluide wie Metallschmelzen eingesetzt wurde. Potentielle Anwendungen sind heiße und chemisch aggressive sowie nicht transparente Flüssigkeiten, da hier verfügbare Durchflussmesstechniken nur bedingt anwendbar sind.