钢包浇注末期汇流旋涡形成机理及影响因素

FORMATION MECHANISM AND INFLUENCE FACTORS OF SINK VORTEX DURING LADLE TEEMING

采用数值模拟并结合实验的方法,研究了Coriolis力、出水口位置、流体初始切向速度等因素对汇流旋涡产生过程的影响,此外还研究了具有一定切向运动的流体在浇注过程中切向速度、径向速度的变化规律.研究表明,初始流体静止时,Coriolis力是汇流旋涡产生的主要原因,且汇流旋涡产生的原始驱动力来自于出水口附近处的流体旋量;初始流体静止时出水口位置对旋涡临界高度的影响不明显,但是当流体具有一定的初始速度时出水口偏离中心可以使旋涡的产生高度显著降低,此时流体的切向运动是汇流旋涡产生的根本原因;流体初始切向运动速度对汇流旋涡的临界高度影响显著,初始角速度越大,汇流旋涡产生时刻越早,临界高度也越高,因此给予流体一定的静置时间、降低其湍流程度是抑制汇流旋涡卷渣的重要举措;汇流旋涡的起旋高度HSS与初始角速度w的关系式为HSS=0.11+2.85w-4.04w2+1.95w3,空气柱贯通至出水口的高度HCS与w的关系式为HCS=0.09+1.49w-0.79w2,拟合度均在0.99以上.

To investigate the formation mechanism of sink vortex during ladle teeming, the effects of some factors such as Coriolis force, the position of the ladle shroud and initial tangential velocity of the fluid on the vortex formation process have been studied using numerical simulation combined with experiments. In addition, the evolution tendencies of tangential and radial velocities of the fluid over radial position were studied at certain initial tangential velocity. The results show that as for fully settled fluid, Coriolis force is the major reason for sink vortex formation and the spinor near the shroud is the initial driving force. There is no obvious effect of the ladle shroud position on the critical height of vortex for fully settled fluid, while the critical height of vortex significantly decreases with increasing shroud eccentricity for the fluid with a certain initial velocity, and the tangential motion is the main driving force for vortex formation in this case. The initial tangential velocity affects the critical height significantly. The larger the initial angular velocity is, the earlier vortex occurs and the bigger the critical height of vortex is. As a result, keeping the fluid settled for some time is an effective measure to delay vortex during ladle teeming. The relationship between the start height of vortex（HSS） and initial angular velocity（w） can be expressed as HSS=0.11＋2.85w-4.04w2＋1.95w3, and that of the height of air column extending to shroud（HCS） and w expressed as HCS=0.09＋1.49w-0.79w2, both of the fitting degrees are higher than 0.99.