圆环挡板振荡流反应器浓度场的数值模拟

CFD Study on the Concentration Patterns in an Orifice-Baffled Oscillatory Flow Reactor

采用有限体积元方法对五腔室圆环挡板振荡流反应器(OFR)的三维浓度场进行了数值模拟研究,考察了腔室中心注入模式下的示踪剂浓度场的分布形态及其在不同振荡条件下的演化情况。研究表明,示踪剂在OFR中运动是由振荡流反应器中主体流动与漩涡构成的二次流动对腔室中心区域的交替控制促成的。定义一个腔室中的浓度方差 C 作为判断混合效率的依据,结果表明,C 值是腔室内混合和腔室间混合共同作用的结果。参数表征的混合效率说明振荡雷诺数越大,混合效率越高。统计分析结果表明,基于长程对流混合和短程湍流扩散双模式传递模式的二项指数衰减曲线方程能够较好地描述踪剂浓度分布方差值随时间的变化。

Numerical simulation study on the 3-dimensional concentration field of an orifice-conic-baffled oscillatory flow reactor （OFR） was carried out by employing finite volume method. Distribution pattern of tracer concentration under mode of injection in the cell center was investigated and concentration field transition under different oscillatory conditions was also researched. The results showed that the movement of tracers was caused by the control in turn of mainstream and secondary flow region which was constituted by vortices. Define concentration variance C of a cell as criterion of mixing efficiency and the results come that C was a result cooperated by mixing in the cell and mixing between cells. Parameter C was used to symbolize mixing effect and it showed higher Oscillatory Reynolds Number, higher mixing efficiency. The statistic results indicated that the second order exponential function, which was based on two-pattern transfer model consisted of long distance mixing and short turbulent dispersion, could be successfully used to fit the change of concentration variance with time.