Extremum in the dependence of the head generated by electromagnetic pump of liquid metal on feeding current frequency

Magnetohydrodynamic processes that take place in the coaxial channel of an induction electromagnetic pump for liquid metal have been studied. The main purpose of the work is to develop a new method for the real-time measurement of the physical properties of a liquid metal coolant for fast reactors of nuclear power plants. The property control systems are, as a rule, combined with the systems for cleaning the liquid-metal coolant from undesirable impurities, since the latter change the physical characteristics of the coolant, such as electrical conductivity, thermal conductivity, viscosity, and density. It is stated that the problem can be overcome by analyzing the characteristics of the electromagnetic pump, which is an obligatory element of systems for purifying the coolant and monitoring its properties. Particular emphasis is placed on studying the characteristic, which can be rapidly measured by the devices incorporated in the control system. The head generated by the electromagnetic pump related to the frequency of the current feeding the inductor windings (all other factors being the same) is best suited for this purpose. In this work, the values of the pressure drop for the electromagnetic pump are determined at different flow rates of liquid metal in a certain range of electrical conductivity. The same dependences were determined experimentally using the same electromagnetic pump that runs on the gallium eutectic with a known exact value of electrical conductivity. It turned out that all these dependences have an extremum. It has been found that the calculated frequency of the electric current, which provides the extremum of the head, coincides with the experimental one, provided that in the calculations, the gallium eutectic is used as the working liquid. Thus, using the results of mathematical modeling along with physical measurements one can promptly determine the unknown current value of electrical conductivity. The results obtained serve as the basis for the developed method to monitor the purity of a liquid metal coolant.