特殊地形条件下火焰附着对森林地表火蔓延的影响机制与规律研究

在高坡度、峡谷等特殊地形火蔓延过程中，火前锋不断向前倾斜、甚至附着于可燃物表面，可诱发火蔓延突然加速。以往的研究主要集中于中低坡度条件下的稳态火蔓延；当发生火焰附着，稳态火蔓延假设不再成立，现有模型无法准确预测火蔓延速率。本项目拟开展高坡度、峡谷火蔓延的系统性实验研究，揭示特殊地形条件下火焰附着的临界条件。研究火焰附着对火前流场的影响规律，建立控制火羽流的物理方程，揭示火焰附着的形成机制。研究火焰附着对火焰形态参数、温度、流场和热流的影响规律，揭示火焰附着对可燃物预热的影响机制。建立火蔓延预测的物理模型，系统阐释火焰附着对火蔓延加速的作用机制。形成特殊地形条件下火焰附着对火蔓延加速的科学认识，对森林火灾的扑救和指挥决策提供理论依据及科学指导。

Under special terrain conditions including higher slopes and canyon, the flame front inclines and gradually attaches to the fuel bed surface, which may induce sudden acceleration of fire spread. Previous studies mainly focused on the steady fire spread under low and medium slope conditions. When the flame attachment occurs, the steady-state fire spread hypothesis is not valid, thus the existing models cannot accurately predict the rate of fire spread. This project intends to carry out fire spread experiments under the high slope and canyon terrains, respectively. It aims to reveal the critical condition and formation mechanism of flame attachment. The evolution of flow velocity during the flame attaching to the fuel surface will be studied. The physical equation controlling the fire plume will be established to reveal the formation mechanism of the flame attachment. The effect of flame attachment on flame geometry parameters, temperature, flow velocity, and heat flux will be investigated, to reveal the influence of flame attachment on the fuel preheating mechanism. The physical model of fire spread will be developed, to explain the influence of flame attachment on fire spread acceleration, and to form a scientific understanding of the mechanism of flame attachment on fire spread. This work will provide a theoretical basis and scientific guidance on forest fire fighting.