Experimental Study of Liquid Metal Flow for the Development of a Contact-Less Control Technique

Abstract

The article presents an experimental study on the flow of an eutectic gallium alloy in a cylindrical cell, which is placed in an alternating magnetic field. The magnetic field is generated by a coil connected to an alternating current source. The coil is located at a fixed height in such a way that its plane is perpendicular to the gravity vector, which in turn is parallel to the axis of the cylinder. The position of the cylinder can vary in height with respect to the coil. The forced flow of the considered electrically conductive liquid is generated due to the action of the localized electromagnetic force. It is assumed that under the action of the alternating magnetic field, the liquid is heated uniformly, and the resulting heat is quickly absorbed by the forced flow, so that liquid free convection can be neglected. The experiment is carried out using an ultrasonic Doppler anemometer. One transducer is installed in the axially located cylinder sluice and the other transducer is placed in the near-wall region. According to the results, a velocity profile, corresponding to a two-tori flow pattern can be hardly obtained in the low frequency range of the power supply. However, this is possible in the high frequency range. The average velocity profiles depend essentially on the location of the coil relative to the cell. The spectral analysis of velocity signals shows that the amplitude of the velocity pulsations is comparable to the average value of the flow velocity. Such experimental results and their verification through comparison with numerical calculations are intended to support the development of new methods for reducing the intensity of vortex flows during the electromagnetic separation of impurities through an electromagnetic induction mechanism (able to produce an electromotive force that displaces particles). KEYWORDSUltrasonic doppler velocimeter; electrically conductive medium; azimuthal pinch; experiment in liquid metal; magnetohydrodynamics Nomenclature B Magnetic field (T) f Frequency of velocity pulsations (Hz) f e Coil frequency (Hz) f em Electromagnetic (pinch) force (N/m 3 ) H Height of cylindrical cell (m) Ha Hartmann number