Numerical studies on internal fire whirls (IFW) generated in a vertical shaft model with a single corner gap were reported in this paper. The generation of IFW, burning rate of fuel and temperature were studied experimentally first. Numerical simulations on medium-scale IFW were carried out using a fully-coupled large eddy simulation incorporating subgrid scale turbulence and a fire source with heat release rates compiled from experimental results. Typical transient flame shape was studied and then simulated numerically by using temperature. The dynamic phenomena of generation and development of IFW were simulated and then compared with experimental results. The predicted results were validated by comparing with experimental data, which demonstrated that an IFW can be simulated by Computational Fluid Dynamics. Numerical results for flame surface, temperature, and flame length agreed well with the experimental results. The IFW flame region and intermittent region were longer than those for an ordinary pool fire. The modified empirical formula for centerline temperature was derived. Variations of vertical and tangential velocity in axial and radial directions were also shown. The vortex core radius was found to be determined by the fuel bed size. Velocity field was not measured extensively due to resources limitation. Comparing measured temperature distribution with predictions is acceptable because temperature is related to the heat release rate, air flow and pressure gradient.

本文报道了在具有单个角间隙的垂直轴模型中产生的内部火旋风 (IFW) 的数值研究。首先对IFW的产生、燃料的燃烧速度和温度进行了实验研究。中尺度 IFW 的数值模拟是使用全耦合大涡模拟进行的，该模拟结合了亚网格尺度湍流和一个火源，其热释放率由实验结果汇编而成。研究了典型的瞬态火焰形状，然后使用温度进行数值模拟。模拟了IFW产生和发展的动态现象，并与实验结果进行了比较。通过与实验数据的比较验证了预测结果，这表明计算流体动力学可以模拟IFW。火焰表面的数值结果，温度、火焰长度与实验结果吻合较好。IFW 火焰区和间歇区比普通池火长。推导出了修正的中心线温度经验公式。还显示了轴向和径向的垂直和切向速度的变化。发现涡核半径由燃料床尺寸决定。由于资源限制，速度场没有被广泛测量。将测得的温度分布与预测值进行比较是可以接受的，因为温度与放热率、气流和压力梯度有关。推导出了修正的中心线温度经验公式。还显示了轴向和径向的垂直和切向速度的变化。发现涡核半径由燃料床尺寸决定。由于资源限制，速度场没有被广泛测量。将测得的温度分布与预测值进行比较是可以接受的，因为温度与放热率、气流和压力梯度有关。推导出了修正的中心线温度经验公式。还显示了轴向和径向的垂直和切向速度的变化。发现涡核半径由燃料床尺寸决定。由于资源限制，速度场没有被广泛测量。将测得的温度分布与预测值进行比较是可以接受的，因为温度与放热率、气流和压力梯度有关。