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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。
Spiral flow is generally generated by tangential inflow, the installation of deflector or rotating pipe, but Horii et al. Experimentally found that three devices also produced a very stable spiral flow. In this paper, the formation process and mechanism of one kind of spiral flow are studied by numerical simulation. The calculation results confirm the evolution of double vortex structure to single vortex structure and reveal the advantages of shrink pipe and the difference between different propensity inflows. In the numerical simulation, the linear, the second and the third order turbulent eddy-viscosity modes are selected, but the numerical experiments show that the linear and second-order modes have little difference between them. It shows that the second-order eddy viscosity mode does not play an important role in the numerical simulation of the turbulent spiral flow Big. While the third-order mode shows the ability to predict the asymmetry into the asymmetric structure of the transformation.