Numerical Investigation on MHD Flow and Heat Transfer of Bubble-liquid Metal in a Vertical Upward Channel
Due to the influence of strong magnetic field,the flow of liquid metal is suppressed in the cooling system of fusion reactor,where bubbles are injected to mix the liquid metal flow and reduce the effect of Magnetohydrodynamic(MHD),thus increasing the heat transfer rate.Based on VOF multiphase flow model,the upward flow and heat transfer characteristics of bubble-liquid metal in vertical channel are numerically investigated under the transverse magnetic field upon varying magnetic field intensity from 0 to 1.3 T and bubble Reynolds numbers from 1.3×104 to 6.76×104.The results show that the columnar flow appears in the absence of magnetic field.However,owing to the pinch effect of MHD,the gas column is broken up and the bubble flow is formed in the presence of magnetic field.With the increase of the magnetic field intensity,the bubble separation position moves upward gradually from the inlet and its velocity also increases.Compared with liquid metal flow,the average heat transfer coefficient of bubble-liquid metal two-phase flow declines with the increase of magnetic field intensity and bubble Reynolds number.Meanwhile,because the two-phase flow can significantly reduce the pressure drop caused by MHD effect,the thermal performance index in the channel is improved,and the improvement magnitude is greater when the magnetic field intensity is smaller.
two phase flowVOF modelMHD effectsheat transfer coefficientthermal performance index
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