3D MHD simulation of pressure drop and fluctuation in electromagnetic pump flow

Electromagnetic (EM) pumps, which drive liquid metals by electromagnetic force for Fast Reactor, had been developed. Annular Linear Induction Pumps (ALIPs) are one of EM pumps. There are some reports in which a drop and a fluctuation of the developed pressure occurred near the top of the developed pressure and flow rate relation curve (P-Q curve). This phenomenon was reported by Gailitis, Kirillov and Araseki. They simulated it using two-dimensional (2D) code and reported that it was characterized by vortices, which were initiated by azimuthal non-uniformity of sodium flow velocity and/or magnetic field, in the liquid sodium flow. We have calculated the developed pressure of EM pump by 2D magnetohydrodynamics (MHD) code and designed an EM pump. It was found that the code simulated the developed pressure with high accuracy in normal operations. When the flow rate was lower than one in the top of P-Q curve, the developed pressure's drop and fluctuation occurred. The fluctuation would disturb the stable operation of the pump. For avoiding this phenomenon, the EM pump's design becomes sometimes too conservative. To evaluate the quantitative effect of this phenomenon and occurred conditions, we have developed a new three-dimensional(3D) MHD code. Clarification of these conditions and its phenomena will enable us to design a new structure or determine operation conditions. This paper presents the simulation results in terms of the generation of a developed pressure's drop and fluctuation occurrence. We used initial conditions which had azimuthal non-uniformity of sodium velocity to simulate vortices in the liquid sodium. Our 3D MHD code simulated the developed pressure's drop and fluctuation by vortices in radial and circumferential direction. It was confirmed that the vortices developed in the radial direction and then the vortices in circumferential direction developed.