基于多股移动火焰相互影响机制研究的固体火蔓延机理

Fire spread is one　of the most important subprocedure in fire and the existing research focuses on the flame spread over a single slab. However, the lack of study on flame spread in moving multi-fire which occurs frequently in exterior wall of building fires and forest fires is extremely serious. Experimental research and theoretical analysis of flame spread in moving multi-fire are conducted in this project based on the study of some important parameters, including spatial distribution of feedback heat flux, temperature distribution in solid and flame spread rate, during flame spread over a single slab of typical material and the established corresponding model. Through a series of experiments, including different materials, dimension, experimental condition and geometric relationship, the mutual influence between different flame and the controlling mechanism of flame spread in moving multi-fire in complicated conditions are studied. Furthermore, the criterion of the mergence of multi-flame and the effect of interaction between the moving multi-fire on the stability of spread process, spatial distribution of feedback heat flux and heat and mass transfer between gas and solid phase are also investigated. Subsequently, a spread model of moving multi-fire are developed based on the analysis in which the thermal degradation in solid, heat transfer and chemical reaction kinetics in gas are taken into account. This research will improve the current situation of the lack of flame spread of moving multi-fire and will also provide important reference for the establishment of related fire safety standards and regulations, and thus the significance of the project is extremely important for theory and reality.

火蔓延是火灾最重要的分过程之一，已有研究主要针对单一平板火蔓延展开，而对建筑外墙火灾和森林火灾经常会出现的多股移动火源火蔓延过程的研究十分缺乏。本项目首先研究典型材料单一平板火蔓延过程中火焰反馈热流空间分布、固相温度分布和火蔓延速率等重要参数及控制机理并建立相应模型，以此为基础，开展多股移动火源火蔓延的实验研究和理论分析。通过多种材料、多类尺寸、多种工况及多种几何关系的实验研究，深入了解复杂条件下多股移动火源火蔓延过程中不同火焰间的相互影响规律和控制机制，探索多股移动火源火焰间相互作用对火蔓延稳定性、反馈热流时空分布、气固相之间传热传质的影响规律和火焰合并的临界条件，进而通过理论分析建立耦合固相热解、气相传热和化学反应动力学的多股移动火源的火蔓延模型。本项目将极大改善多火源火蔓延问题研究缺乏的现状，为相关火灾安全标准和规范的制定提供科学依据，具有极其重要的理论意义和实用价值。

火蔓延是火灾最重要的分过程，但一直以来对建筑外墙火灾和森林火灾常会出现的多股移动火源火蔓延过程的研究较为缺乏。4年来，本项目对多股移动火源火蔓延过程进行了卓有成效的研究，深入揭示了从可燃物着火到单一平板火蔓延，最后到多股移动火源火蔓延过程中的基本规律与控制机理。火蔓延过程是可燃物在火焰前锋处不断热解并着火的过程，本项目首先从可燃物热解着火着手，实验研究了多种典型材料在多工况、多热流条件下的固相温度分布、质量损失速率、着火时间等关键参数的变化规律，建立了时变热流下热解数值模型，实现了不同种类热流、不同材料特性、不同外部环境下的可燃物着火时间的快速准确预测。以此为基础，进一步研究了典型材料单一平板火蔓延过程中的辐射热流空间分布、固相温度分布、火蔓延速率和火焰形态等重要参数的控制机理并建立了相应模型，准确预测了单一平板在不同环境压力、不同边界条件、不同尺度下三维火蔓延速度。最后，基于以上研究结果，开展了多股移动火源火蔓延的实验研究和理论分析。通过多种材料、多类尺寸、多种压力及多种几何关系的实验研究，获得了复杂条件下多股移动火源火蔓延过程中火蔓延速率、火焰形态、质量损失速率、热解前沿角等参数的变化特征，深入揭示了多股移动火源火蔓延过程中不同火焰间的相互影响规律和控制机制，通过理论分析耦合固相热解、气相传热和化学反应动力学，建立了多股移动火源火蔓延模型，对多股移动火源的火焰融合现象、反馈热流时空分布、气固相传热传质机理做出了合理解释，成功预测了多股移动火源的火蔓延过程。本项目研究结果对建筑火灾和森林火灾相关标准和规范的制定提供了坚实的科学依据。