摘要
本文提出了一种描述带有相变的气固二相混合对流问题的数学模型和数值计算方法。高温融溶液滴在逆向气体流场中经历有三个阶段:液相冷却,固化和固相冷却。对于液滴的运动边界(相变)问题,本文提出了一种变时间步长焓法进行求解。气体颗粒二相流动、采用Eulerian-Lagr-aigian方法。对于Rayligh数大于10~6的湍流,本文应用了两方程(K-ε)模型。修正的SIMPLE方法和四阶Rlunge-Kutta法用来进行数值迭代求解。本文对一种直径为20米。高度为50米的尿素造粒塔作了简化,并完成了数值计算。文章表明浮升力对有相变的运动液滴历程有重要影响。本文所得的一些结果分析对工业尿素塔的设计有指导意义。
A mathematical mcdel for describing gas solid two phase steady mixed convection with phase change has been developed and numerical calculation method is presented. A melting liquid droplet in the contergas flow experiences three processes, cooling of liquid droplet, solidification and cooling of the solid particle. The tubulent model used for Rayleigh number than 166 is a two equation (k-e) model of turbulence. For phase change, an improved enthalpy method with varied time step is proposed. The gas partiele two phase flow is using by Eulerin-Lagrangian approach. Modified SIMPLE algorithm and Runge-Kutta method are used in interative calculation. As an example of calculation, the flow in a special 2-dimensional axi-symmetrical prilling tower of diameter 20 mm and height 50 m has been performed. Buoyancy effect is important for moving droplet with phase change. The model to be developed and analysis of results obtained in this paper are useful for engineering design in industry.
关键词
两相流
气-固
相变
混合对流
Gas solid two phase flow, Mixed Convection, Phase chang
