基于Fluent的城镇中低压燃气管线喷射火事故的后果研究

Tracing the aftermath of the jet fire spray accidents with the urban medium and low pressure gas pipeline via Fluent

为了对城镇中低压燃气管线喷射火事故进行有效的风险评估,根据典型事故案例创建了城镇路面埋地燃气管线泄漏场景,建立模型并划分网格,使用Fluent进行模拟计算,得到了不同泄漏口孔径、不同泄漏口形状、不同管内压力等工况下喷射火的火焰长度、火焰中心面温度分布和临近区域内的热流密度,并通过分析不同工况下的火焰形态和热辐射分布,探讨初始条件对事故后果的影响程度。结果表明:此类型喷射火长度可达数十米,火焰最高温度为2 000 K左右,最高温度位置的高度不超过火焰长度的30%;下风向的热流密度较其他方向更强;在50 mm的泄漏口孔径和0.38 MPa的管内压力下,泄漏口为梭子形,较泄漏口为圆形时的热流密度在下风向整体大15.2%。最后,根据模拟结果构建了快速风险评估模型。

The paper is aimed to fulfill an effective risk assessment for the jet fire accidents likely to happen in the urban medium and/or lower pressure gas pipelines based on the typical accident case study sample research by creating a scenario with some leakage going on from the underground-buried gas pipeline under an urban road surface. For the said study purpose,we have built up a model which can be divided into a number of grids,so as to make known the flame temperature distribution of the jet fire and the thermos flux in the close areas at the different working conditions,including the varied leakage outlet diameters/shapes and the various tubing pressures via the Fluent for analog calculation.And,for each respective working condition,we have worked out the fire flame length and the distribution regularity of the flame kernel shape-form. And,then,we have to identify and determine the relation between the thermos flux density received at some point from the flame and the distance from the said point to the flame itself by fitting the data and information collected on the thermos flux density around the flames. Comparing the flame length with the thermos radiation spray in the different working conditions,it would be possible to find that the flame of the jet fire can probably reach tens of meters,with its length being positively correlated with the leakage outlet and the pipeline pressure.At the same time,the maximum temperature of the flame can be found as high as about 2 000 K,with its maximum temperature height not being over 30% of its length. Besides,the thermos flux density in the downward wind direction is likely to be stronger than that in the other directions. And,in the working conditions with the leakage hole being 50 mm in diameter and 0. 38 MPa of the pipeline pressure,the thermos flux density in the downward wind direction in case that the outlet is like a shuttle in shape would be 15. 2% greater than that in the downward wind one if the outlet is circular in shape. And the thermos flux density at a certain point outside the flame ought to increase with the increase of the outlet diameter,and tends to first decrease but then increase with the decrease of the piping pressure. Finally,the simulation results can help us to establish a prompt risk assessment model based on the above simulation and make a proper assessment of the damage degree of the flames to the people at the same time on site promptly after the accident,so as to provide available assistance to the decision-making for the emergency rescues.