基于通风网络区域划分法的矿井火灾多维度混合模型研究

This project aims to develop a co-simulation method to predict key variables of a mine fire based on the two-zone theory. When a mine fire occurs, the underground ventilation airways can be divided into two zones: a fire zone and a smoke contaminated zone. Fire zone and smoke contaminated zone are treated separately using numerical modeling attributed to their differences in physical and chemical characteristics. The fire zone is more complex compared to the smoke contaminated zone. Geometrical properties, heat transfer effects and fire/ventilation interactions are incorporated in the proposed model. A 3D numerical model based on Finite Volume Method (FVM) will be applied to the fire zone. Sensitivity analysis will be implemented on the Influence factors after the simulations. Influence factors’ database will be created to store the simulation results. Alternatively, the properties of smoke contaminated zone are dominated by hot smoke propagation. A numerical model based on Finite Difference Method (FDM) will be developed in this zone to simulate the heat transfer and species transportation phenomena. The two models will be coupled on the interface between the fire zone and smoke contaminated zone to develop a transient, hybrid modeling method. The proposed hybrid simulation (co-simulation) method could be utilized to solve the problems with relatively high error of temperature prediction obtained by the FDM code in the vicinity of the fire and the unaffordable calculation cost for a whole mine fire simulation using the 3D FVM method.

本项目以矿井火灾数值模拟技术为研究背景，针对火灾发生时火区和烟流污染区的不同热流体力学特性分别进行建模，并在两个区域的分界面上建立参数耦合的混合模拟模型。对于物理模型复杂的火区采用三维有限体积法（FVM），系统性的研究多因素对火区场模型的影响。模拟结果将用于火区边界的确定。数据将进行统计学分析各因素的影响，并编入影响因素数据库。对于高温烟流在通风网络中的传递，本项目将采用计算成本更低的一维有限差分法（FDM）进行建模。在两个不同维度的计算域间的界面上运用面积积分法进行瞬态耦合，建立一种多维度混合模拟模型。本项目通过对火区场模型的特性研究可以解决在混合模型中火区边界确定难的问题。所建立的多维度混合模拟模型又可以解决一维火灾模拟软件对火区流场预测误差大和三维模拟计算代价高而无法用于复杂通风网络的难题。本项目可以为了解多因素影响下矿井火灾火区的特性做出贡献，并建立一种高效而经济的矿井火灾模拟模。

本项目将有限差分法（FDM）和有限体积法（FVM）应用于矿井外因火灾的模拟。它基于更加先进的计算流体力学控制方程的简化形式。一维的有限差分法将矿井巷道各横截面上的各参数看成是均匀分布，用单一节点来表示。计算时对各个节点求解控制方程的简化形式，计算成本较场模型显著降低。本模拟试验的目的是利用基于计算流体力学（CFD）理论的三维矿井火灾数值模拟方法来验证矿井巷道火灾可否简化为一维进行计算。研究过程中应用了基于大涡数值模拟（LES）的CFD火灾模拟软件FDS（Fire Dynamics Simulation）对矿井三种主要巷道：开拓巷道、准备巷道和回采巷道进行模拟。主要考虑火灾对人身伤害的影响，即把温度和有毒有害气体的浓度（主要考虑CO）作为研究的主要内容。影响这两个参数的因素主要有巷道断面尺寸、纵向风速、巷道坡度、火灾功率、火源位置。.项目研究了矿井巷道不同位置横截面上温度及CO浓度变化情况，主要研究同一截面上有限个测点值的变异系数。变异系数是刻画数据相对分散性的一种量度，又称“标准差”。本项目基于该参数对火区范围进行了准确界定，为场-网耦合模型的建立打下基础。