In recent years, there have been reports of gas leakage accidents during the transportation of gas tankers in tunnels, potentially leading to destructive explosions. However, the overall distribution of gas concentration in the entire tunnel has not been experimentally investigated. This study presents a series of brine-water experiments to explore the characteristics of buoyant gas flow in tunnel leakage accidents. The gas distribution is categorized into a stably stratified longitudinal current and a source region. Gas concentration in the tunnel is correlated with the dimensionless reduced gravity, which increases with the source buoyancy flux but decreases with the source release velocity. A model is proposed to estimate the maximum gas concentration of the longitudinal current. The spatial range of the explosive region is influenced by the source buoyancy flux and the leakage velocity. However, the propagation velocity of the longitudinal current is primarily controlled by the source buoyancy flux, with the source momentum having a negligible effect. The thickness of the longitudinal gas flow, δ, linearly decreases from the source region to the tunnel ends. A dimensionless parameter, λ, is introduced to characterize δ. When λ < 1.25, δ rapidly increases with λ and then remains approximately constant when λ exceeds 1.25. This study contributes to a better understanding of buoyant gas flow in tunnel leakage accidents.

中文翻译：

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自然通风隧道竖向瓦斯泄漏产生浮力气流特性试验研究

近年来，不断有煤气罐车在隧道运输过程中发生瓦斯泄漏事故，并可能导致破坏性爆炸的报道。然而，整个隧道瓦斯浓度的整体分布尚未经过实验研究。本研究提出了一系列盐水实验，以探索隧道泄漏事故中浮力气流的特征。气体分布分为稳定分层纵向流和源区。隧道内气体浓度与无量纲折合重力相关，无量纲折合重力随着源浮力通量的增加而增加，但随着源释放速度的增加而减小。提出了一种模型来估计纵向电流的最大气体浓度。爆炸区域的空间范围受源浮力通量和泄漏速度的影响。然而，纵向流的传播速度主要受源浮力通量控制，源动量的影响可以忽略不计。纵向气流的厚度 δ 从源区到隧道末端线性减小。引入无量纲参数 λ 来表征 δ。当λ＜1时1.25 中，δ 随 λ 快速增大，然后当 λ 超过 1.25 时保持近似恒定。这项研究有助于更好地了解隧道泄漏事故中的浮力气流。