圆盘反应器流场数值模拟

Simulation of the Flow Field of a Vertically Rotating Disc Reactor

以圆盘反应器的开发和应用为背景,根据反应器内气液两相的流动特点和接触方式,采用流体体积函数（VOF）模型研究圆盘表面液膜厚度、速度分布和槽内液相流型,得到反应器的流场特性.从轴功率、持液量两方面对反应器性能进行研究,并考察了流场和性能的关系.结果表明,圆盘表面液膜分为起始区、加速区和匀速区.起始区液膜厚,速度慢,部分液体回流;加速区液膜变薄,加速,表面更新快;匀速区膜厚和速度变化较小.液相主体以Stewartson 流型为主,盘间距对液相流型影响明显.圆盘液膜与槽内液相通过“垂直涡”进行物质传递,当圆盘间距与圆盘直径之比（L/D）为0.2-0.4 时,最有利于两者混合和物质传递.将数值模拟和量纲分析结合,得到功率数（NP）和平均膜厚表达式,并与文献进行比较,表明计算流体力学（CFD）方法能够较好的模拟圆盘反应器内流体力学特性,预测流场和性能.

The aim of this paper is to explore the application of CFD in RDC design, by using the volume of fluid model. The film thickness and velocity distribution on the disc surface, bulk liquid flow pattern have been numerically simulated in the reactor. The performance of the reactor, especially the power and the liquid thickness have been studied with CFD. The effect of discs spacing on the flow field and performance was also investigated. The result showed that the liquid film on the disc surface according to its characteristic can be divided into initial region, accelerating region and uniform region. In initial region, the liquid film is the thickest and its motion slowest, and party of the liquid back flow. In accelerating region, the liquid film is thinner and faster. In uniform region, film thickness and velocity is nearly constant. The liquid flow pattern is Stewartson flow and discs spacing have major influence on liquid flow pattern. "Vertical vortex" is the main way of mass exchange between discs and tank. WhenL/D is between 0.2 and 0.4, it is beneficial to mixing in the tank. Based on numerical simulation and dimensional analysis, the correlation equation of power number and the expression of average film thickness were obtained. Comparing with the literature, it was showed that CFD method can simulate the hydrodynamics of disc rotating reactor and predict its flow field and performance perfectly.