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

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