舱室壁火仿真的不同亚格子模型适用性分析

Applicability Analysis of Various Subgrid-scale Turbulent Models in Wall Fire Simulation

有限空间舱室内墙壁火灾具有很大危害性,为研究火灾大涡仿真时不同新型亚格子模型的适用性,对半封闭实验舱室中墙火蔓延和火灾烟气运动过程进行了大涡仿真。分别采用常系数Smagorinsky模型、动力学Smagorinsky模型、Deardorff模型及Vreman模型等不同的亚格子模型与混合物分数燃烧模型结合,分析得到了舱室内烟气温度、主要组分浓度及地面辐射热流密度随时间的变化,将数值仿真得到的结果与实验测量结果进行了比较分析。结果表明,采用常系数Smagorinsky模型计算耗时最少,采用动力学Smagorinsky模型耗时最多。四个亚格子模型对主要组分浓度和辐射热流密度的预测精度基本相等,但Deardorff模型对烟气温度的预测结果与实验结果最接近,综合考虑仿真精度和计算耗时采用Deardorff模型最合适。

Fires in an enclosure compartment often pose great hazard. In order to investigate the applicability of various subgrid- scale turbulent models newly developed for specific physical processes, the wall fire in an experi- mental semi - confined compartment was studied in detail using the Large Eddy Simulation （LES） method of turbu- lence. Each subgrid - scale model was integrated with the multi - mixture fraction combustion model respectively, The subgrid - scale models were considered here,including the constant coefficient Smagorinsky model, the dynamic Smagorinsky model, Deardorf model and Vreman model. The time variations of the smoke temperature, volumetric concentration of chemical species and radiant heat flux to floor were obtained and compared with the experiment test data. It shows that the constant coefficient Smagorinsky model is most time -saving, while the dynamic Smagorinsky model is most time - consuming. The four sub - grid models get almost same precision - calculating in volumetric concentration of chemical species and radiant heat flux to floor, but Deardorff model gets the best precision -calculat- ing in the smoke temperature, and is the best choice considering precision -calculating and time -consuming.