Investigation of Hydrodynamics and Heat Transfer of an Upward Liquid Metal Flow in a Rectangular Channel under a Coplanar Magnetic Field

Resumo

Hydrodynamics and heat transfer were investigated of an upward liquid metal flow through a rectangular channel having an aspect ratio of approximately 3 : 1 and one-sided heating under a coplanar magnetic field (MF). The flow in the cooling system’s cooling channel for a liquid metal blanket module of a Tokamak type thermonuclear reactor is simulated. Experiments were carried out in the mercury magnetohydrodynamic (MHD) test facility. Local heat transfer characteristics were measured using a probe technique. Two types of thermocouple probes were used: a lever-type pivoted probe for detailed measurements of velocity and temperature fields in a channel cross-section and a longitudinal probe for taking measurements along the heated zone in the channel. A correlation method was used for measuring local velocity. The distributions of averaged velocity and temperature, the distributions of dimensionless wall temperature along the cannel perimeter, and characteristics of flow temperature fluctuations are presented. The distributions of averaged and instantaneous wall temperatures along the channel were obtained. The effects caused by an increase in the intensity of temperature fluctuations in a coplanar magnetic field were revealed. It is the authors' opinion that natural convection is responsible for formation and separation of large-scale vortex structures, the axis of which is parallel to the magnetic field induction vector, at the heated wall. These vortices bring about temperature fluctuations that often exceed the level of turbulent fluctuations. The data on heat transfer should be considered in designing MHD cooling channels of a fusion reactor.