【摘要】 LNG低温储罐完整性管理对保障天然气安全储运和平稳贸易具有重要现实意义与工程价值。现有常规无损检测技术难以满足在役LNG低温储罐连续监测需求，分布式光纤应变传感技术为此提供了新路径，具备良好的推广应用前景。为此，开展了基于LNG低温储罐罐壁的分布式光纤应变仿真研究，基于光纤沿线连续应变感知能力，使用COMSOL和Fluent两种仿真软件分别模拟了静载与扰动工况下的流固耦合应变响应，采用差值法、小波变换法开展缺陷特征识别，结合空间坐标映射实现缺陷定位，并引入半宽高法对缺陷尺寸进行了估算。研究结果表明：(1)该方法可有效识别直径40～100 mm、深度约10 mm的孔洞类缺陷；(2)缺陷位置的空间映射误差小于30 mm，相对误差小于1%，尺寸估算误差小于20%；(3)在参数设置相同的前提下，Fluent仿真耗时约10 min，优于COMSOL的30 min计算时长。结论认为，该仿真模型验证了分布式光纤传感技术在低温储罐缺陷识别中的适用性，为LNG储罐结构的在线健康监测提供了技术思路。更多还原

【Abstract】 The integrity management of LNG cryogenic storage tank is of crucial practical significance and engineering value for ensuring the safe storage and transportation and smooth trading of natural gas, whereas the existing conventional nondestructive inspection technologies can hardly meet the requirement of in-service LNG cryogenic storage tanks for continuous monitoring. To address this problem, the distributed optical fiber strain sensing technology provides a new path, presenting promising promotion and application prospects. In this paper, the distributed optical fiber strain based on the wall of LNG cryogenic storage tank is simulated. Then based on the continuous strain sensing capability along the optical fiber, fluid-structure interaction strain responses under the working conditions of dead load and disturbance are simulated using two types of simulation software packages, namely COMSOL and Fluent, respectively. In addition, defect characteristics are identified by means of difference method and wavelet transform method, defect positioning is achieved based on spatial coordinate mapping, and defect size is estimated using the half-width method. The following results are obtained. First, this method can effectively identify the porosity defects with a diameter of 40-100 mm and a depth of approximately 10 mm. Second, the spatial mapping error for defect locations is less than 30 mm, with a relative error below 1%, and the size estimation error is less than 20%. Third, under identical parameter settings, Fluent simulation takes approximately 10 minutes, outperforming COMSOL which requires 30 minutes of computation time. In conclusion, the simulation model validates the applicability of distributed optical fiber sensing technology to the defect identification in cryogenic storage tanks, providing a technical approach for online health monitoring of LNG storage tank structures.更多还原