一种强螺旋流现象的数值试验研究

Numerical studies on a sort of strongly swirling flows

螺旋流一般通过切向进流、安装导流片或旋转管道三种方式产生 ,但Horii等人通过实验发现有三种装置也产生了非常稳定的螺旋流。本文利用数值模拟对其中的一种螺旋流形成过程与机制进行了研究。计算结果证实了双涡结构向单涡结构演化现象并揭示了收缩管道的优点以及不同倾向进流的区别。在数值模拟时本文分别选取了线性、二及三阶涡粘性湍流模式 ,但数值实验表明线性与二阶模式的计算结果差别不大 ,说明在数值模拟湍流螺旋流时二阶涡粘性模式作用不大。而三阶模式则表现出具有预测对称性进流向非对称结构转化的能力。

In general, swirling flows in pipes are generated by three means: tangentially inleting medium; guiding fluids by vanes with a certain angle and axially rotating pipe. But experiments of Horii and his co workers discovered that three kinds of apparatuses can also cause swirling flows with none of the three methods. In our work, the velocity fields of the swirling flow took place in one of the three apparatuses were simulated. The results confirmed the phenomenon of asymmetric double vortices evolving into a single vortex and showed the merits of the contracting portion as well as the distinctions between the different inflow manners. By comparison of the results of linear, quadratic and cubic turbulent models, the cubic model's irregularity of breaking symmetry was exposed.