隔板搅拌槽流动与混合性能的数值研究

Numerical investigations on the flow and mixing performance of baffled-stirred tank

层流搅拌时,搅拌槽的混合效率普遍较低。为了改善搅拌效果,在桨叶上下方混合隔离区处对称布置了4块隔板,以截断隔离区内流体运动轨迹的周期性,并以甘油为介质,对有无隔板时Rushton桨在层流状态下的流动与混合过程进行了研究,分析了槽内流场结构、速度分布及功率消耗情况。结果表明,隔板不仅能改变槽内流体的流型,增强轴向循环能力,提高混合效果,而且消耗的功率低,仅为同条件下无隔板时功率消耗的76%。

The mixing efficiency of stirred tank is usually not high when it is operated under laminar conditions. In order to improve the mixng performance, four baffles were symmetrically fixed at the places above and below the blades to truncate the flow periodicity of the fluid within the IMRs. The laminar flow and mixing processes with and without baffles were numerically investigated. The working fluid was viscous glycerin. The flow fields, velocity distributions, mixng performance and power consumption were systematically analyzed. Results show that the method proposed in this paper is a good modification on the standard Rushton turbine, which can alter the flow patterns within the stirred tank, increase the velocity of the fluid and strengthen the axial circulatory flow ability. Besides, the power consumption is only 76% of that consumed by the Rushton turbine.