Experimental study on complex flow of a binary mixture in Czochralski configurations with different aspect ratios and rotation rates

Abstract

This paper reported the experimental study on complex flow stability of a binary mixture in the Czochralski configurations subjected to a radial temperature gradient. The working fluid was the n-decane/n-hexane mixture with an initial mass fraction of 50%. Results show that the rotation of crucible and crystal can promote the flow destabilization at a small aspect ratio. However, the crucible rotation can suppress the flow instability at a large aspect ratio. When the thermocapillary Reynolds number exceeds a certain threshold value, the hydrothermal waves, the bud shaped and fringes spokes appear in proper order with the increase of the aspect ratio. Furthermore, the flow patterns are also dependent on the crystal and crucible rotation rates. When the crystal and crucible rotate synchronously, the temperature fluctuation frequency in the binary mixture is nearly the same with that in the pure fluid at a small aspect ratio; however, there is a large difference at a large aspect ratio. Moreover, the temperature fluctuation amplitude in the binary mixture is greater than that in the pure fluid at a small aspect ratio, but it is contrary at a large aspect ratio.