强磁场对突扩管中液态金属剪切层的影响

Influence of the High Magnetic Fields on the Shear Layer of Liquid Metal Sudden Expansion Flow

在聚变堆中,由于强磁场的影响,液态金属流动呈现准二维流动的特征。本文基于SM82模型,对不同磁场强度下突扩管内的流动进行数值研究。计算结果表明,随着磁场强度增大,流动从不稳定状态向稳定状态转变,剪切涡脱落逐渐消失,并伴随着剪切涡纵向尺寸变窄,横向关联尺度变长,剪切层脉动特征频率趋于一致。同时,脱落后的剪切涡与壁面相互作用是影响管道换热的主要因素,随着磁场强度增加,壁面平均努塞尔数逐渐减小,换热效率降低。

In the nuclear fusion reactor,due to the influence of a strong magnetic field,the flow of liquid metal presents the characteristics of a quasi-two-dimensional flow.Based on the SM82 model,a numerical study is conducted on the flow in a sudden expansion duct under different magnetic field intensity.The results show that as the magnetic field strength increases,the flow changes from an unstable state to a stable state,and the shedding of shear vortices gradually disappears.As the longitudinal size of the shear vortex becomes narrower,the transverse correlation scale becomes longer,and the characteristics frequency of shear layer tends to be consistent.At the same time,the interaction between the shear vortex and the wall surface is the main factor affecting the heat transfer of the duct.With the increase of the magnetic field strength,the average Nusselt number(Nu)of the wall gradually decreases,and the heat transfer efficiency decreases.