在聚变堆中,由于大温差和强磁场的影响,液态金属自然对流呈现出了不同于常见流体的流动和换热特征.本文基于自主研发的磁流体计算程序,通过三维直接数值模拟,研究了平行于温度梯度的水平磁场对封闭方腔中液态金属流动与传热的影响.分析了不同磁场强度下,方腔内的流动与传热,包括主环流、二次流、温度分布及Nu数分布等,并从机理上解释了磁场的影响.结果表明平行温度梯度的水平磁场对自然对流有抑制作用,磁场越强,抑制越明显,传热效率越低.“,”In the nuclear fusion reactor, where the temperature differences and magnetic fields are strong, natural convection of liquid metal shows different flow and heat transfer characteristics. In the present work, three-dimensional (3D) numerical simulations are conducted to study the natural convection in an electrically insulated cavity with imposed horizontal magnetic fields parallel to the main circulation, where two opposite vertical walls are kept at different temperatures and the other four are thermally insulating. We mainly focus on flows and heat transfer with the variation of Hartmann (Ha) number, including the main circulation, second flow, temperature fields and Nusselt number (Nu). Our numerical results confirm that the horizontal magnetic fields suppress the convection and heat transfer.