公路隧道内CNG管束气瓶车泄漏天然气扩散CFD仿真

CFD simulation of natural gas diffusion from CNG tube-buddle cylinder vehicle leakage in highway tunnel

气体管束气瓶车是运输压缩天然气(Compressed Natural Gas,CNG)的重要工具,针对CNG管束气瓶车运输过程中在公路隧道内发生追尾导致泄漏问题,基于计算流体动力学CFD方法,建立CNG管束气瓶车遭追尾致泄漏后果预测与评估模型,对公路隧道内风场条件下泄漏天然气的扩散过程进行模拟与分析,研究CNG管束气瓶车泄漏天然气在隧道内的扩散规律和形成的危险区域范围。仿真结果表明:泄漏天然气扩散具有极速泄漏、外力作用、初期膨胀增长和稳定收缩等特征;喷射气云团能够覆盖肇事车辆前部,可能导致驾驶人员窒息或引发火灾、爆炸事故;实例工况下,泄漏气体扩散至稳态以后,形成爆炸极限浓度范围内的气云分布在肇事车辆前部1.5m至肇事车辆中部之间的区域;进行事故应急响应时,应封锁事故隧道,加强隧道内通风,在消防水枪的稀释掩护下对管束气瓶车进行堵漏作业。

The gas tube-buddle cylinder vehicle is an important tool for transporting compressed natural gas（ CNG）. Aiming at the leakage problem during the transportation process of CNG tube-buddle cylinders vehicle in highway tunnel due to rearend collision,the prediction and assessment model of leakage consequence was built based on the computational fluid dynamics（ CFD） method. Then,the diffusion process of natural gas after leakage under the conditions of wind field in highway tunnel was simulated and analyzed,and the diffusion laws of natural gas in highway tunnel and the range of corresponding dangerous area were investigated. The simulation results showed that the diffusion of natural gas from CNG tube-buddle cylinder vehicle leakage has the characteristics of rapid leakage,external force acting,expansion growth in initial stage,steady contraction,etc. The jet gas cloud can cover the front of the accident vehicle,which may cause the choking of the driver or the fire and explosion accidents. Under the conditions of actual case,when the diffusion of natural gas reached the steady state,the gas cloud within the scope of explosion concentration limit mainly distributed in the area between the front 1. 5m and the central part of the accident vehicle. During the accident response process,the highway tunnel should be blocked,the tunnel ventilation should be strengthened,and the sealing and plugging operation for CNG tube-buddle cylinder vehicle should be conducted under the dilution cover of fire nozzles.