Large eddy simulation of fire plumes

FireFOAM, a new fire modeling code based on the OpenFOAM platform (www.openfoam.org), is developed and applied to model a series of purely buoyant fire plumes with heat release rates from 14 to 58 kW. The calculations are compared with McCaffrey’s (1979) experiments. The simulation results demonstrate good quantitative agreement with experimental measurements, and show the scaling relations of mean temperature and velocity in the continuous flame, intermittent and plume regions. The numerical simulations are shown to be strictly conservative in energy. Predicted flame heights and entrainment rates also compare well with experimental correlations. The good agreements in all aspects examined show that the current CFD model performs well for small-scale fire plumes. Turbulent fluctuation intensities and PDF of mixture fraction are presented to gain more insights into the structure of fire plumes.     

基于时间序列与灰色拓扑的春节火灾损失预测

火灾每年给中国带来了巨大的损失,春节期间的火灾损失更是严重.根据1999-2010年春节期间火灾统计资料,火灾四项指标数据具有时序性以及随机波动性、模糊性.运用时间序列与灰色拓扑预测方法相结合预测春节期间火灾发生规律,且预测出未来3年内的火灾发生情况.结果表明,时间序列预测模型的平均绝对误差较小,且所建立的灰色拓扑预测模型的拟合精度都达到"好"的标准.因此,采用时间序列与灰色拓扑预测模型相结合对春节火灾发生情况进行预测,其结果合理可靠,可供理论研究和消防部门做出相应的预防措施参考,以达到有效控制和预防春节火灾的目的.     

Determination of Platinum,Palladium, Ruthenium,Rhodium, and Iridium in Ultrabasic Rock from the Great Dyke of Zimbabwe by Inductively Coupled Plasma–Optical Emission Spectrometry

Platinum, palladium, ruthenium, rhodium, and iridum were determined in ultrabasic rock from the Great Dyke of Zimbabwe by inductively coupled plasma optical emission spectrometry. The limits of detection for these elements were less than 7 ng/g. The samples were fused at 1100°C to separate the noble metals which were enriched into a nickel sulfide button and dissolved in hydrochloric acid. The insoluble noble metals were filtered, dissolved in aqua regia in a boiling water bath, and determined by inductively coupled plasma optical emission spectrometry. This method was employed for the characterization of large quantities of ultrabasic rock from the Great Dyke of Zimbabwe.     

森林地表火火行为预测预报系统

本文从地表火蔓延的本质入手，建立了一整套求解地表火行为特征量的数学模型，并运用现代软件编制技术，成功地编制出预测预报地表火行为的计算机软件。该系统能预测复杂地形、气象条件和可燃物分布情形下，火蔓延过程中不同阶段的火行为状况。算例结果表明，系统在预测结果的合理性和准确性等方面优于美国的BEHAVE程序。     

FIRE OCCURRENCE PATTERNS AT LANDSCAPE LEVEL: BEYOND POSITIONAL ACCURACY OF IGNITION POINTS WITH KERNEL DENSITY ESTIMATION METHODS

ABSTRACT. Based on kernel density estimation methods, this paper introduces an alternative approach of fire occurrence modeling that addresses the inherent positional inaccuracies of recorded wildland fire ignition points. These observations, recorded in longitude and latitude using only degrees and first minutes, contain positional inaccuracies of about ± 700 to ± 925 meters in x and y axes. Kernel density estimation was applied to these historical fire observations recorded between 1985 and 1995 in Halkidiki peninsula, Greece, as well as, to simulated inaccurate points into which positional inaccuracies of the same magnitude were randomly introduced. Substantial differences were observed when a regular grid of quadrants was superimposed over the two point distributions. Although, at higher grid resolution these mismatches were minimized, the problem of generalization appeared. Contrar‐ily, the concept of “moving window” assisted to retain high grid resolution and minimize the effect of inaccurate point observations. In addition, the kernel approach, which considers also the relative position of points within the “moving window,” produced more realistic estimates.     

船舶密闭舱室火灾过程及其模拟计算

密闭舱室火灾是一个三维非定常过程，压力升高是这一过程的重要特征。本文采用质量守恒的方法进行压力校正，建立了计算密闭舱室火灾过程的数学物理模型，数值计算采用非均匀交错网格，结果与实验和理论分析相符较好。     

建筑物内火灾烟羽流和顶蓬射流诱发的空气运动盐水模拟实验研究

盐水在清水中的扩散与火灾烟气在空气中的蔓延相似，因而可用盐水的扩散来模拟火灾烟气的蔓延；同样地，由于盐水的扩散而导致的环境清水的运动也可用来模拟烟气蔓延诱发的空气运动。基于这一原理，本文用实验的方法，研究了建筑物内初起火灾产生的烟羽流和顶蓬射流所诱发的空气运动，并对走廊空气层生长规律和运动特性进行了初步的测量和分析。所得结果基本合理，对建筑物通风排烟及疏散通道设计有帮助，从而为建筑火灾环境空气的运动的实验研究开辟了新的思路，也为火灾区域模拟提供了实验依据     

轴心受压H型截面钢柱火灾行为的试验研究

本文对4根H型截面钢柱进行了火灾行为的试验研究。全部火灾试验采用自行研制的火灾试验炉,试验结果表明炉子性能稳定,使用方便。试验采用足尺试验形式,柱长3300mm。钢柱轴心受压,其中两个限制轴向变形,另两个不限制轴向变形。柱两端采用单向刀口支座,允许钢柱绕强轴转动。钢柱试验中考虑荷载大小和是否限制轴向变形两个因素。通过试验,得出了钢柱在火灾下的侧向变形和轴向变形随温度变化情况。试验证明:钢柱受火时,轴向变形明显的分为膨胀阶段和压缩阶段。压缩阶段很短,一旦进入压缩阶段,钢柱很快破坏。钢柱受到的外加荷载越大,其极限温度越低。限制轴向变形的钢柱极限温度降低。试验研究为今后钢结构火灾行为研究提供了依据。     

Comfortable, flexible upholstery fire barriers on base of bast, wool and thermostable fibres

The paper presents elastic barrier materials developed at the INF which play a role of filling and fire barrier material at the same time in upholstery furniture, reducing the development and spread of fire on flammable materials. The presented results of flammability and biophysical tests confirm the comfort of products.The developed barrier materials use natural fibres (wool, flax FR) characterized by good air permeability, hygroscopicity, moisture transport, elimination of electrostatic charges and have effect on climate of interiors also when blended with thermostable fibres such as Polyacrylate. These flexible structures based on blend of natural fibres and thermostable fibres with at least two barrier effects i.e. durable resistance to fire, thermal insulation, control of electrostatic phenomena.     

Comprehensive Theoretical and Experimental Studies on the CF3H Fire‐extinguishing Mechanism

In order to clarify the chemical suppression mechanisms of CF₃H, experimental and theoretical studies were conducted respectively in this paper. Firstly, the combustion species in low pressure laminar premixed flat methane flames with CF₃H addition is measured by synchrotron radiation molecular beam mass spectrometry (SR‐MBMS) experimentally. Fire suppression chemistry of CF₃H is investigated by selective detection of combustion radicals and intermediates in experimental process. Secondly, quantum chemistry calculations are performed to calculate the potential energy surfaces (PES) for the CF₃H unimolecular dissociation reaction and reactions of CF₃H with free radical OH and H at the B3LYP/6‐311++G** and QCISD(T)/6‐311++G** levels. Finally, the chemical suppression mechanism of CF₃H was discussed by comparing the theoretical calculation with experimental measurement.