Investigation of Heat Transfer of Liquid Metal in a Rectangular Vertical Channel in a Coplanar Magnetic Field Applied for Cooling System of a Tokamak Reactor

Abstract

The results of experimental studies of liquid metal flow under conditions typical for channels of the heat exchanger for a prospective thermonuclear reactor ITER (International Thermonuclear Experimental Reactor) were presented. A descending flow in a rectangular channel with a ratio of sides 1: 3 in a coplanar magnetic field at the two-side heating was considered. Such a configuration of flow is typical for Russian–Indian development of a blanket test module of ITER. This article analyzes the experimental results obtained on the unique mercury stand RK-2 on the evolution of temperature pulsation under a magnetic field. The regimes at the absence of low-frequency high-amplitude pulsations with a low effect of thermogravitational convection were implemented. As in the case of flow in a round pipe, the secondary flows take place at the full suppression of turbulence due to the influence of free convections and at the flowing in a round pipe. The secondary flows were found in the rectangular channel. The shape of pulsations' intensity profiles obtained in a transverse section of channel has a clearly observed M-shaped form, which is preserved under application of a magnetic field. Therefore, it was concluded that the degree of suppression of pulsations depends not on the distance to wall but is determined only by regime parameters. This conclusion made it possible to formulate the exponential dependence characterizing the degree of suppression of turbulence pulsations by the coplanar magnetic field for the flat channel and also the boundaries of its applicability on the basis of results of analysis and treatment of experimental data. Accounting for the influence of pulsations' suppression by the coplanar magnetic field is performed by the correction of the formula for determination of the turbulent viscosity in corresponding Reynolds equations.