固/液界面前沿液流流场和动量界面层

Fluid Field and Momentum Boundary Layer Adjacent to S/L Interface Front

首次在带有对流驱动器的水平Bridgman强制性晶体生长装置上,采用定速摄影对透明模型合金(SCN-Ace.)液体对流的流场及流动型式进行了精确测量,并对动量界面层厚度进行了计算.结果表明:经驱动器施加的对流具有古艾特(Couette)层流特性;所测得的S/L界面前沿的流速分布均在动量界面层内.此区域内的强制对汉将对枝晶间距及形成麦穗晶有重要影响.

For many years, the first author has engaged in research that requires a clear understanding of fluid field and momentum boundary layer adjacent to S / L interface from. Crystal Growth Laboratory took many years in evolving the special equipement needed for obtaining experimentally such a clear understanding. It is believed that for the first time, such special equipment makes it possible to carry out in-site observation and precise measurement systematically of flow field offluid convection on transparent model alloy (SCN-Ace.) by horizontal Bridgman constraint crystal growth apparatus using fixed-speed photography. Experimental results indicate that convection driven with special driver is of the character of Couette laminar flow. Thickness calculation of momentum boundary layer by approach integral method is also conducted. Qualitative agreement is found between theoretical calculation and experimental results on SCN-Ace. alloy. Fluid velocity distribution measured adjacent to S / L interface front is within momentum boundary layer. Constrained convection in this zone possesses significant influence on growth direction, arm spacing of dentrite crystal and 'wheat-head' crystal formation.