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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In this paper, we present an application for realizing high-precision horizontally directed force measurements in the order of several tens of nN in combination with high dead loads of about 10 N. The set-up is developed on the basis of two identical state-of-the-art electromagnetic force compensation (EMFC) high precision balances. The measurement resolution of horizontally directed single-axis quasi-dynamic forces is 20 nN over the working range of ±100 μN. The set-up operates in two different measurement modes: in the open-loop mode the mechanical deflection of the proportional lever is an indication of the acting force, whereas in the closed-loop mode it is the applied electric current to the coil inside the EMFC balance that compensates deflection of the lever to the offset zero position. The estimated loading frequency (cutoff frequency) of the set-up in the open-loop mode is about 0.18 Hz, in the closed-loop mode it is 0.7 Hz. One of the practical applications that the set-up is suitable for is the flow rate measurements of low electrically conducting electrolytes by applying the contactless technique of Lorentz force velocimetry. Based on a previously developed set-up which uses a single EMFC balance, experimental, theoretical and numerical analyses of the thermo-mechanical properties of the supporting structure are presented.

In this paper, we present enhanced flow rate measurement by applying the contactless Lorentz Force Velocimetry (LFV) technique. Particularly, we show that the LFV is a feasible technique for metering the flow rate of salt water in a rectangular channel. The measurements of the Lorentz forces as a function of the flow rate are presented for different electrical conductivities of the salt water. The smallest value of conductivity is achieved at 0.06 S•m −1 , which corresponds to the typical value of tap water. In comparison with previous results, the performance of LFV is improved by approximately 2 orders of magnitude by means of a high-precision differential force measurement setup. Furthermore, the sensitivity curve and the calibration factor of the flowmeter are provided based on extensive measurements for the flow velocities ranging from 0.2 to 2.5 m•s −1 and conductivities ranging from 0.06 to 10 S•m −1 .