The effects of surface vortex on the drawdown and dispersion of floating particles in stirred tanks were investigated. Particle distribution and power consumption were analyzed by experiments and numerical simulations in both baffled and unbaffled tanks agitated by a Rushton impeller. In unbaffled tanks, a non-aggregation rule was applied and the average dispersion index was found to serve as a reasonable prediction of the full drawdown of floating particles. The critical impeller speeds in an unbaffled tank were higher than those in a tank with vertical baffles. At each immersion depth in a baffled tank, particles distributed more uniformly and more power was consumed. Comparison of snapshots of the baffled and unbaffled tanks shows that the surface vortex increases the drawdown speed while it decreases the particle distribution uniformity and power consumption. Therefore, the use of baffles to suppress the surface vortex provides for a more uniform particle distribution in stirred tanks.

研究了表面涡流对搅拌槽中漂浮颗粒的垂降和分散的影响。通过实验和数值模拟分析了在Rushton叶轮搅动的带挡板和不带挡板的储罐中的颗粒分布和功耗。在无挡板的水箱中，应用了非聚集规则，并且发现平均分散指数可作为漂浮颗粒全部降落的合理预测。在没有挡板的水箱中，临界叶轮速度要高于在带垂直挡板的水箱中的临界叶轮速度。在挡板箱中的每个浸入深度处，颗粒分布更加均匀，并且消耗了更多的能量。折流板罐和不折流板罐的快照比较表明，表面涡流增加了垂降速度，同时降低了颗粒分布的均匀性和功耗。因此，使用挡板抑制表面涡流可在搅拌釜中提供更均匀的颗粒分布。