Thermal mixing enhancement of liquid metal MHD free-surface flow by optimizing vortex generator arrays

Abstract Liquid divertor concepts in fusion reactor research have been widely studied. Recently, thermal mixing enhancement of the locally heated free-surface of liquid metal MHD (Magneto-Hydro-Dynamics) film flow using one vortex generator was proposed and investigated by the authors. In this study, an inline arrangement of many hemispherical protrusions to generate many vortices in their wakes was proposed, and the transport characteristics of high temperature fluid at the free-surface to the bottom (i.e., thermal mixing) in liquid metal MHD film flow was investigated experimentally. The experiments for three streamwise pitch lengths between the protrusions under various transverse magnetic field strengths (B = 0.00–0.33T) for two flowrate conditions were conducted. As the results, the heat flux distributions on the bottom wall of the film flow and the efficiency of heat transport showed the existence of the optimum streamwise pitch length for the thermal mixing enhancement even under relatively high transverse magnetic field. Therefore, the inline arrangement of many hemispherical protrusions can be considered as one of the candidates for thermal mixing enhancement methods of liquid metal MHD free-surface flow application.