Experimental study of liquid metal heat transfer in a vertical duct affected by coplanar magnetic field: Downward flow

Abstract

Liquid metal flows under a high thermal load and strong magnetic field are of great interest in the context of the development of fusion reactor cooling systems. In this study, a downward flow of mercury in a heated duct, affected by a coplanar magnetic field (directed transverse to the main flow and along the long side of the duct), is studied experimentally for symmetrical (two-sided) and asymmetrical (one-sided) duct heating, showing different flow behaviors in the magnetic field. We show that in spite of the qualitatively different structure of the downward flow in the duct with different heating modes, the applied coplanar magnetic field provides a rather general reaction, which includes two scenarios determined by the Richardson number. At high Richardson numbers (Ri≳1), the Nusselt number tends toward the turbulent limit, as expected in the channel without a magnetic field, and at low Richardson numbers (Ri≲1), the Nusselt number tends to its laminar limit.