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研究了永磁体螺旋磁场作旋转运动,驱动金属液所产生的三维流动行为.采用超声波Doppler测速仪,对金属液的流速进行了定量测量分析.通过周期性改变螺旋磁场的旋转方向,完全实现了频域模式变化的螺旋磁场.研究了不同模式参数下,金属液在圆柱形容器内周向和轴向流动速度的变化情况.结果表明:本实验条件下金属液的周向流动,随着磁场的周期性换向也出现周期性的往返流动,周向流速的幅值在模式周期T_m大于40s后达饱和.轴向流动是螺旋磁场的移动分量引发的轴向环流和旋转分量驱动的二次流共同作用的结果.模式磁场作用下轴向流动存在最佳模式周期T_m~*.当模式周期小于T_m~*时,轴向流动出现了周期性的往返流;大于T_m~*时,二次流开始形成并逐渐成为主要的流动形态.
The three-dimensional flow behavior of molten metal caused by the helical magnetic field of a permanent magnet was studied. The flow rate of the molten metal was quantitatively analyzed and analyzed by ultrasonic Doppler velocimeter. By periodically changing the direction of rotation of the helical magnetic field, Frequency domain mode changes of the spiral magnetic field.Metal fluid under different mode parameters in the cylindrical container axial and axial flow velocity changes.The results show that: the experimental conditions of the liquid metal flow in the circumferential direction, with the magnetic field , The amplitude of the circumferential flow velocity is saturated after the mode period T_m is greater than 40s.The axial flow is the secondary driven by the axial circulation and the rotation component caused by the moving component of the helical magnetic field When the mode period is less than T_m ~ *, the axial flow has a periodic back-and-forth flow. When it is larger than T_m ~ *, the secondary flow Flow begins to form and gradually becomes the dominant flow pattern.