不同湍流模型在中间包钢液流动数值模拟中的适用性研究

Study on applicability of different turbulence models in simulation of molten steel flow in tundish

连铸中间包内部结构复杂,钢液流动状态多样,详尽准确的钢液流场信息是中间包控制和优化的前提。数值模拟方法已广泛应用于中间包内钢液流场研究,钢液流场的精确数值模拟离不开合适的湍流模型及相应的边界条件。基于CFD开源代码包OpenFOAM v8,分别应用标准k-ε模型、RNG k-ε模型、SST k-ω模型3种湍流模型,对称面边界、自由滑移边界2种液面边界条件,对中间包流场进行了数值模拟。通过与文献中实验结果比较,发现采用SST k-ω模型可以成功预测RTD曲线的“双峰”,且响应时间、峰值时间与实验结果较为接近;应用SST k-ω模型时,将液面边界类型由自由滑移改为对称面,获得的示踪剂响应时间的误差由93.89%降低至8.35%以下,峰值时间的误差由100.78%降低至12.32%左右。因此,SST k-ω模型、对称面液面边界可以较好地描述中间包内钢液流动过程。

The internal structure of continuous casting tundish is complex,and the flow state of molten steel is diverse.Detailed and accurate information of molten steel flow field is the premise of tundish control and optimization.Numerical simulation method has been widely used in the study of molten steel flow field in tundish.The accurate numerical simulation of molten steel flow field is inseparable from the appropriate turbulence model and the corresponding boundary conditions.Based on the CFD open-source code OpenFOAM v8,three different types of turbulence models(standard k-εmodel,RNG k-εmodel,and SST k-ωmodel)were applied to simulate the molten steel flow in the tundish.Additionally,two boundary conditions of symmetry plane and the free slip were also applied.Comparing the simulation results to the experimental data,it shows the RTD curve obtained by the simulation with the SST k-ωmodel can successfully predict the"double peaks"that appeared in the experiment.Besides,the response time and peak value time are closest to that of experimental results.For SST k-ω,when changing the type of liquid surface boundary from free slip to symmetrical plane,the error of tracer response time obtained is reduced from 93.89%to less than 8.35%,and the error of peak time is reduced from 100.78%to about 12.32%.It can be concluded that the SST k-ωmodel and the symmetry boundary are applicable for the simulation of molten steel flow in the tundish.