Preliminary experimental study on applicability of Lorentz force velocimetry in an external magnetic field

Abstract

Lorentz force velocimetry (LFV) is a noncontact technique for measuring electrically conducting fluids based on the principle of electromagnetic induction. This work aims to answer the open and essential question of whether LFV can work properly under a surrounding external magnetic field (ExMF). Two types of ExMFs with different magnetic intensities were examined: a magnetic field with a typical order of 0.4 T generated by a permanent magnet (PM) and another generated by an electromagnet (EM) on the order of 2 T. Two forces, including the magnetostatic force between the ExMF and PM in the LFV, and the Lorentz force generated by the PM in LFV were measured and analyzed in the experiment. In addition, ExMFs of varying strengths were added to the LFV, and the location of the LFV device in the iron cores of the EM was considered. The experimental outcomes demonstrate that it is possible for a LFV device to operate normally under a moderate ExMF. However, the magnetostatic force will account for a high proportion of the measured force, thus inhibiting the normal LFV operation, if the ExMF is too high.