A study on fire plume behaviour in cross-winds.

侧风中火羽行为的研究。

基本信息

批准号：
16310109
负责人：
OKA Yasushi
金额：
$ 9.98万
依托单位：
Yokohama National University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16310109/
关键词：
fire plume cross wind merged fame trajectory position temperature width of fire plume 温度場温度幅

项目摘要

On the basis of the experimental study using a single fire source and/or multiple fire sources focusing on the flame shape and fire plume behavior in the presence of crosswinds, the following conclusions were obtained.(1)Dimensionless formula for the apparent flame height of an inclined flame under the influence of cross-wind has been developed based on the modified dimensionless heat release rate, Froude number and equivalent length of burner. An empirical formula also has been developed to predict the flame tilt angle considering the burner shape. This model is derived from the balance of mass fluxes of wind and hot current, combined with centreline properties of a fire plume.(2)An empirical formula for predicting the position of an inclined fire plume axis by applying the logistic function including the variables expressed by the combination function of heat release rate and crosswind velocity was proposed. A new formula for estimating the velocity along the inclined fire plume axis … More using the values of the temperature rise, crosswind velocity and travelling distance was developed based on the assumption that there is a virtual ceiling at the upper limit of the height that the hot current can reach. Further, the behaviour of this hot current, influenced by the crosswind, closely resembles the ceiling jet that flows under this virtual ceiling. This correlation is useful, and it is applicable for the estimation of the velocity along the fire plume axis irrespective of the presence of a crosswind.(3)The section shape of the inclined fire plume was experimentally clarified based on the plume width defined by temperature. In addition, it was shown that the temperature distribution in the inclined fire plume was expressible as the sum of two kinds of Gaussian distributions, one is temperature distribution directory carried from the fire source and the other is carried from the upstream by the cross-winds.(4)The reproducibility of the fire plume properties in the cross-winds was examined by using two kinds of CFD codes. It became clear that the height of the continuous flame and the position of the fire plume axis were able to be reproduced to some degree by applying the combustion model and by devising the method of setting the heat release rate. Two kinds of CFD codes showed mutually different results. Moreover, the temperature decreasing properties along the inclined fire plume were different with the experimental results.(5)The empirical formulae for predicting the apparent flame height, the position of an inclined fire plume and the temperature decreasing along an inclined fire plume for a single fire source were examined whether it was possible to apply by comparing them with the experimental results with multiple fire sources in cross-winds. Less

通过对单火源和/或多火源在侧风作用下火焰形态和火羽行为的实验研究，得到以下结论。(1)火焰表观高度的无量纲公式基于修正的无量纲热释放率、弗劳德数和燃烧器的等效长度，建立了侧风影响下的倾斜火焰模型，并建立了一个经验公式来预测考虑燃烧器形状的火焰倾斜角。是从平衡得出的风和热流的质量通量，结合火羽流的中心线特性。(2)应用逻辑函数（包括热释放率组合函数表示的变量）预测倾斜火羽轴位置的经验公式基于存在虚拟天花板的假设，提出了一种利用温升、侧风速度和行进距离的值来估计沿倾斜火羽轴的速度的新公式。热流高度上限此外，受侧风影响的热流的行为与在虚拟天花板下流动的天花板射流非常相似，并且无论如何，它都适用于估计沿火羽流轴的速度。 (3)基于由温度定义的羽流宽度，通过实验阐明了倾斜火羽的截面形状。此外，还表明倾斜火羽中的温度分布可以用总和来表示。的两种高斯分布，一种是来自火源的温度分布目录，另一种是由上游侧风带来的温度分布目录。(4)使用两种CFD代码检验了侧风中火羽流特性的再现性很明显，通过应用燃烧模型并设计两种 CFD 代码显示的热释放率设置方法，可以在一定程度上再现连续火焰的高度和火羽轴的位置。而且，沿倾斜火羽的降温特性与实验结果也不同。(5)预测表观火焰高度、倾斜火羽位置及沿倾斜火羽降温的经验公式。通过与侧风中多个火源的实验结果进行比较，检验了单一火源的羽流是否可以应用。