管廊管道泄漏数值模拟网格敏感性分析

The Grid Sensitivity Analysis of Numerical Simulation for Gas Pipeline Leakage in Utility Tunnels

摘要: 为研究地下综合管廊中天然气泄漏扩散的行为特性，以南宁市新邕路综合管廊燃气舱防火分区9为研究对象，建立了三维CFD模型，并利用ANSYS Fluent软件对燃气泄漏过程进行了数值模拟。通过与试验数据对比验证了模型的可靠性与准确性。在此基础上，进行了网格敏感性分析，对五种不同网格划分方案(406,972至587,419个网格)进行了评估。研究发现，当网格数量达到468,668时，各监测点的甲烷浓度变化曲线在全时间范围内基本一致，进一步细化网格对结果影响有限，证明该网格方案在保证精度的同时有效平衡了计算效率。同时，还从扩散初期(0~15秒)和长期稳定阶段(>15秒)对气体浓度变化的敏感性进行了深入分析。结果显示，靠近泄漏源区域对网格划分更为敏感，而远离泄漏源区域的浓度变化趋势相对平稳。研究表明，该CFD模型能够可靠地捕捉复杂环境下气体泄漏与扩散的特性，可为综合管廊的安全设计与风险评估提供技术支持。

Abstract: To investigate the behavioral characteristics of natural gas leakage and diffusion in underground utility tunnels, this study takes Fire Compartment 9 of the gas chamber in the Nanning Xin Yong Road utility tunnel as the research object. A three-dimensional CFD model was established, and numerical simulations of the gas leakage process were conducted using ANSYS Fluent software. The model was validated by incorporating experimental data, demonstrating that the relative error between simulated and experimental data was less than 10%, thus confirming the reliability and accuracy of the model. A grid independence analysis was subsequently performed, evaluating five grid division schemes ranging from 406,972 to 587,419 cells. The results revealed that when the grid count reached 468,668, the methane concentration curves at all monitoring points remained consistent over the entire time range, and further grid refinement had minimal impact on the results. This finding indicates that this grid scheme effectively balances accuracy and computational efficiency. Furthermore, the sensitivity of gas concentration changes was analyzed in depth during the early diffusion phase (0~15 seconds) and the long-term stabilization phase (>15 seconds). The results showed that regions near the leakage source were more sensitive to grid resolution, while concentration trends in areas further from the source were relatively stable. This study demonstrates that the CFD model reliably captures the characteristics of gas leakage and diffusion in complex environments and provides technical support for the safety design and risk assessment of utility tunnels.