Heat transfer suppression mechanism of magnetogasdynamic flow in a circular tube subjected to transverse magnetic field regulation

Abstract

A transverse magnetic field (TMF) perpendicular to the flow direction can control the magnetogasdynamic (MGD) flow and heat transfer characteristics in circular tubes, which has broad application prospects in many fields. However, the influence law of magnetic field on the MGD flow and heat transfer characteristics are not clear. Considering the Joule heating effect and the transition gradient of the magnetic field, this study utilized numerical calculations to analyze the variations of parameters including the current, electromagnetic force, and Joule heat in a partially magnetized circular tube and reveal the influence law and regulation mechanism of an applied TMF on flow and heat transfer characteristics. The results show that the flow and heat transfer of the Hartmann and Roberts layers exhibit anisotropy, which becomes prominent as the Hartmann number (Ha) increases. The heat transfer exhibits suppression resulting from the effect of the magnetic field on turbulence in the MGD flow. Moreover, the average Nusselt number (Nu) in the magnetized region increases initially and then decreases as Ha increases. The varying gradient of the magnetic field causes high-velocity jets near the Roberts layer and generates a large amount of Joule heat, thus enhancing the heat transfer in the magnetic field transition region.