建筑物内非均匀预混天然气泄漏爆炸过程数值模拟

Numerical simulation of leakage and explosion process of inhomogeneous premixed natural gas in buildings

为了应对建筑物内天然气泄漏爆炸给城市公共安全带来的严重威胁,以某天然气爆炸事故为例,借助Flacs软件,研究了天然气的泄漏规律和非均匀预混天然气的爆炸规律。结果表明,在天然气累计泄漏量相同的条件下,当泄漏速率由0.001 kg/s增长至0.09 kg/s时,厨房顶灯处的天然气体积分数由21%升高至39%,增加了18个百分点,而主卧、次卧顶灯处的天然气体积分数分别由18%、16%降至12%、7%,分别降低了6个百分点、9个百分点。在非均匀预混条件下,门窗泄爆压力从30 kPa降至0时,室内超压峰值下降了66%,而在均匀预混条件下,室内超压峰值的下降率为12%。研究结果对于预防类似事故发生和助力爆炸事故调查均具有指导意义。

The leakage and explosion accidents of natural gas that occur in buildings severely threaten a city’s public safety.In this paper,the geometry similar to the accident buildings was built,and the leakage laws of natural gas and explosion characteristics of inhomogeneous premix nature gas were studied by FLACS software based on a past natural gas explosion accident.The results show that,compared to monitor points in the middle of rooms,the volume fraction of nature gas reaches the lower explosion limit earlier in monitor points in the top of the room,so it is essential to check the circuit on time in case of forming ignition source.When leakage velocity increases from 0.001 kg/s to 0.09 kg/s,the volume fraction of natural gas increases from 21.2%to 39%in the monitor points in the top of the kitchen,while the volume fraction of nature gas decreases from 18%and 16%to 11.5%and 7.5%in the master room and secondary room,respectively,based on the same leakage mass of natural gas.Due to the competition between the intensity of explosion and relief capacity,the curve of overpressure with time has double peak structures in the explosion of inhomogeneous premix nature gas.However,it is a single peak in the explosion of homogeneous premix nature gas.The overpressure peak decreases as the decline of relief pressure in the condition of both inhomogeneous and homogeneous premix natural gas.In the condition of inhomogeneous premix,when relief pressure decreases from 30 kPa to 0,the maximum value of overpressure drops by 66%,while it only decreases by 12%in the condition of homogeneous premix.The equivalent gas cloud volume(Q)can characterize the explosion intensity of natural gas,which is an auxiliary method to determine the hazard degree of non-uniform gas clouds in the process of explosion risk prediction.This study is of great scientific significance for preventing similar accidents and assisting the investigation of explosion accidents.