A State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China.
Yangtze Delta Region Academy, Beijing Institute of Technology, Jiaxing 314000, China.
Sensors (Basel). 2023 Jun 8;23(12):5430. doi: 10.3390/s23125430.
Optical fiber sensors are newly established gas pipeline leakage monitoring technologies with advantages, including high detection sensitivity to weak leaks and suitability for harsh environments. This work presents a systematic numerical study on the multi-physics propagation and coupling process of the leakage-included stress wave to the fiber under test (FUT) through the soil layer. The results indicate that the transmitted pressure amplitude (hence the axial stress acted on FUT) and the frequency response of the transient strain signal strongly depends on the types of soil. Furthermore, it is found that soil with a higher viscous resistance is more favorable to the propagation of spherical stress waves, allowing FUT to be installed at a longer distance from the pipeline, given the sensor detection limit. By setting the detection limit of the distributed acoustic sensor to 1 nε, the feasible range between FUT and the pipeline for clay, loamy soil and silty sand is numerically determined. The gas-leakage-included temperature variation by the Joule-Thomson effect is also analyzed. Results provide a quantitative criterion on the installation condition of distributed fiber sensors buried in soil for the great-demanding gas pipeline leakage monitoring applications.
光纤传感器是新兴的天然气管道泄漏监测技术，具有检测微弱泄漏的高灵敏度和适应恶劣环境的优点。本工作通过土壤层对包含泄漏的应力波在被测光纤（FUT）中的多物理传播和耦合过程进行了系统的数值研究。结果表明，传输压力幅值（进而作用于 FUT 的轴向应力）和瞬态应变信号的频率响应强烈依赖于土壤类型。此外，研究发现具有较高粘性阻力的土壤更有利于球形应力波的传播，在考虑传感器检测极限的情况下，允许 FUT 安装在离管道更远的位置。通过将分布式声学传感器的检测极限设置为 1 nε，数值确定了 FUT 与粘土、壤土和粉砂的可行范围。还分析了焦耳-汤姆逊效应引起的含气泄漏温度变化。结果为埋设在土壤中的分布式光纤传感器的安装条件提供了一个定量标准，适用于对天然气管道泄漏监测要求较高的应用。
