Abstract: The laminar stirred tank processing highly viscous fluid and shear sensitive media is scarcely reported. A mathematical model describing the laminar flow and mixing process of highly viscous non-Newtonian fluid in stirred tank with double combined impeller was established. The laminar model, the multiple reference frame (MRF), and the tracer concentration method were used to simulate the flow field and spreading process of tracer. The axial velocity distribution curves, response curves of tracer concentration and mixing time were analyzed. The working medium was blocked with the middle surface moving in each half layer of centrally stirred tank，and the working medium in eccentrically stirred tank had global movement and prominent axial mixing ability. Tracer in stirred tank with axis rotating centrally continued spreading to the lower layer depending on increasing concentration imbalance，tracer in stirred tank with axis rotating eccentrically relied on the asymmetric structure to spread，and tracer in stirred tank with impeller rotating eccentrically relied on the asymmetric distribution of blade. The monitor points which were near to and far away from the feeding point had long mixing time because of oscillation and adjustment，and the monitor point in the middle had the shortest mixing time.

Key words: stirred tank with double combined impeller, stirring eccentrically, non-Newtonian fluids, two-phase flow, laminar model, numerical simulation, stirred tank with double combined impeller, stirring eccentrically, non-Newtonian fluids, two-phase flow, laminar model, numerical simulation

摘要： 目前，处理高黏流体和对剪切敏感介质的层流搅拌槽的报道并不多见。本文建立了描述双层组合桨搅拌槽内高黏非牛顿流体层流流动、混合过程的数学模型，利用Laminar模型、多重参考系法（MRF）和示踪剂浓度法对其流场特性、示踪剂扩散过程进行数值模拟，分析搅拌槽内轴向速度曲线、示踪剂浓度响应曲线和混合时间。结果表明：中心搅拌中间面将介质阻隔在各自的半层内运动，偏心搅拌介质作全局运动，轴向混合能力突出；转轴中心搅拌依靠上下半层浓度差的增大向下扩散，转轴偏心搅拌通过不对称结构扩散示踪剂，叶轮相对转轴偏心搅拌则利用叶片的不对称分布；距离加料点较近和较远的监测点浓度响应曲线因振荡和调整，混合时间较长，处于中间面的监测点拥有最短的混合时间。

关键词: 双层组合桨搅拌槽, 偏心搅拌, 非牛顿流体, 两相流, 层流模型, 数值模拟, 双层组合桨搅拌槽, 偏心搅拌, 非牛顿流体, 两相流, 层流模型, 数值模拟