地下综合管廊作为城市基础设施的重要组成部分,集成了自来水、电力、天然气等多种管线,显著提高了地下空间利用效率,减少了道路开挖。然而,天然气管线一旦在管廊内发生泄漏,其易燃易爆特性将严重威胁管廊及周边设施的安全。因此,研究综合管廊内天然气泄漏的扩散规律对于保障管廊及城市基础设施的安全运行至关重要。采用ANSYS Fluent软件,构建了200 m燃气舱三维模型,并应用Realizable k-ε湍流模型模拟了不同通风状态和泄漏口位置下的天然气泄漏扩散过程。设置了不同的排风速度(无排风、1.5 m/s、2.5 m/s)以及不同的泄漏口位置(距进风口5 m、25 m、50 m、75 m、100 m、125 m)模拟发生泄漏200 s内管廊内甲烷的分布情况。结果表明:排风速度对甲烷气体的扩散具有显著影响;随着通风速度的增加,气体的扩散范围和浓度峰值显著降低,尤其在2.5 m/s的通风条件下,高浓度区域的持续时间和范围大幅减小;泄漏口的位置同样对气体扩散特性起关键作用,靠近进风口的泄漏源气体扩散更快,浓度梯度更平缓;远离进风口的泄漏源易形成高浓度积聚区域,增加了安全风险。

Underground utility tunnels, as a critical component of urban infrastructure, integrate various pipelines such as water supply, electricity, and natural gas, thereby significantly enhancing the utilization efficiency of underground space and reducing road excavation. However, once a natural gas pipeline leaks within the tunnel, its flammable and explosive nature poses a severe threat to the safety of the tunnel and surrounding facilities. Therefore, studying the diffusion patterns of natural gas leaks in utility tunnels is crucial for ensuring the safe operation of these tunnels and urban systems. This study employs the ANSYS Fluent software to construct a three-dimensional model of a 200-meter-long gas compartment. The Realizable k-ε turbulence model is applied to simulate the diffusion process of natural gas leaks under different ventilation conditions and leak locations. Simulations were performed with varying exhaust velocities (no exhaust, 1.5 m/s, and 2.5 m/s) and different leak locations (5 m, 25 m, 50 m, 75 m, 100 m, and 125 m from the air inlet) to analyze the distribution of methane within the tunnel over a 200-second period following a leak. The results show that: Exhaust velocity significantly influences the diffusion of methane gas. As the ventilation speed increases, the diffusion range and peak concentration of the gas decrease markedly, particularly under the 2.5 m/s ventilation condition, where the duration and extent of high-concentration areas are substantially reduced. Additionally, the location of the leak plays a pivotal role in the gas diffusion characteristics. Leaks closer to the air inlet exhibit faster diffusion and a more gradual concentration gradient, whereas leaks farther from the inlet tend to form high-concentration accumulation zones, increasing safety risks.