Abstract: Mixing characteristics of HEV static mixer with different tab gaps and tab wing(the distance between the last tab and the outlet)were studied experimentally and numerically.The most widely used measure for the uniformity is the coefficient of variation(CV).Smaller CV value means more uniform mixture.The volume fraction of tracer fluid was measured at the outlet,and the results were compared with standard k-ε equation,RNG k-ε equation,realizable k-ε equation,SST k-ω equation and standard k-ω equation,based on which the most suitable equation was obtained.Using this model,the CV of tracer fluid with different tab wing was studied when the tab gap was from 0.8D to 2.0D,where D is the inner dimeter of HEV static mixer. The CV of the tracer fluid at different spacing at the same benchmark section was also studied.The results showed that RNG k-ε turbulent model was in a good agreement with the experimental results with the relative error of 3.37%.It was also found that the CV decreased rapidly as the tab gap increased when tab gap≤1.7D and increased as the tab gap increased when tab gap≥1.7D.The optimum tab gap is 1.7D.The attenuation of CV was fast as tab wing increased in a certain distance,and then became comparatively slow.

Key words: static mixer, mixing characteristic, numerical simulation, tab gap, tab wing

摘要： 以变异系数作为评价混合器混合性能的指标,利用实验和数值模拟相结合的方法研究了翼片间距和尾距对HEV型静态混合器混合特性的影响。首先利用实验方法测量了静态混合器出口处示踪流体的体积分数,基于实验结果对数值模拟中的5种湍流模型(standard k-ε、RNG k-ε、realizable k-ε、SST k-ω、standard k-ω)进行对比分析,选出最优计算模型,在此基础上,模拟研究了不同翼片间距在同一基准断面处示踪流体变异系数的变化规律,以及翼片间距在0.8D~2.0D之间时,出口处示踪流体的变异系数随着尾距的变化规律。结果表明:RNG k-ε模型模拟的结果与实验结果最为接近(相对误差为3.37%),即该模型最能真实地反映此混合器的流场特性;HEV型静态混合器混合的均匀程度随着翼片间距的增大呈现先提高再降低的趋势,当翼片间距 ≤1.7D时,随着翼片间距的增大,变异系数迅速降低,当翼片间距 ≥1.7D时,随着翼片间距的增大,变异系数呈上升趋势,翼片间距为1.7D时,CV值最低,混合效果最好;在一定长度范围内,出口处示踪流体的变异系数随着尾距的增加迅速降低,但是尾距增加到一定距离以后,继续增加尾距对混合效果的改善不明显。

关键词: 静态混合器, 混合特性, 数值模拟, 翼片间距, 翼片尾距