液氢因高比能量和广阔应用前景受到了广泛关注, 特别是在航天推进、清洁能源储运等关键领域。然而, 液氢的大规模应用仍面临严峻的安全挑战。液氢具有极低的沸点, 一旦发生泄漏, 将迅速汽化形成氢气云团。在可燃气体浓度范围内, 该云团在遇到火源或静电火花时极易引发燃烧甚至爆炸, 带来严重的安全隐患。因此, 深入研究液氢在开放环境中的泄漏、扩散和挥发行为, 对于制定有效的安全防护策略和应急响应机制具有重要意义。液氢实验具有高风险、技术复杂和成本高等特点, 当前公开发表的液氢释放实验数据极为有限, 严重制约了该领域的深入研究。为弥补这一研究不足, 该文启动并实施了在开放环境中的大规模液氢释放实验项目, 旨在系统获取液氢释放后的扩散特性和演化过程, 构建了一套综合性的液氢释放实验平台, 集成液氢储存与释放系统、传感器阵列系统、远程测控系统和视频及红外监测系统, 具备实时采集关键参数(包括氢体积分数、温度、风速与风向等)和多角度记录氢气云团演化图像的能力。在充分考虑多种环境与操作参数(如风速、环境温度、释放角度、地面覆盖类型和释放流量等)的基础上, 共完成了12组有效释放工况, 该文重点展示了第2组释放实验的结果, 通过布设在地面的多台高清摄像机和配备于空中的云台摄像设备, 从多个角度实时记录氢气云团的空间分布, 传感器阵列系统同步采集了各测点处氢体积分数的动态变化。基于此, 该文将液氢释放过程划分为4个典型阶段：地面扩展阶段、抬升过渡阶段、稳定烟羽阶段和云团消散阶段, 并总结和分析了每个阶段的演化特征。进一步采用开源计算流体力学(computational fluid dynamics, CFD)代码OpenFOAM, 对第2组实验工况进行了三维瞬态的数值模拟, 数值模拟结果与实验观测数据的偏差在正常范围内。该文在公开领域系统提供了液氢在开放环境下大规模泄漏的实验数据, 为相关研究提供了资料参考, 也为与实验相结合的CFD数值模拟提供了理论支撑, 有利于推动氢能产业的安全可持续发展。

Objective: Liquid hydrogen, owing to its remarkably high specific energy and broad application prospects has attracted widespread attention in research and development, particularly in aerospace propulsion and sustainable clean energy storage and transport. However, the practical large-scale use of liquid hydrogen faces notable and demanding safety challenges. Liquid hydrogen has an exceedingly low boiling point; once a leak occurs, it rapidly vaporizes to form a hydrogen cloud. At flammable concentrations, this cloud can ignite or even explode upon encountering a flame or a static spark, posing serious safety hazards. Therefore, an in-depth investigation of liquid hydrogen leakage, diffusion, and vaporization behavior in open environments is crucial for devising effective safety protection strategies and emergency-response mechanisms. Owing to the inherently high risk, technical complexity, and substantial economic cost of liquid hydrogen experiments, publicly available data on liquid hydrogen release remain extremely scarce, severely limiting further progress in this field. Methods: To address this research gap, a large-scale open-environment liquid hydrogen release experiment was executed, aiming to systematically obtain the diffusion characteristics and evolution process of the released liquid hydrogen. For this purpose, a comprehensive experimental platform was built, integrating a liquid hydrogen storage and release system, a sensor-array system, a remote monitoring and control system, and video and infrared observation systems. This platform collects key parameters in real time—including hydrogen volume fraction, temperature, wind speed, and wind direction—and records the hydrogen cloud evolution from multiple angles, ensuring thorough experimental data acquisition. By fully considering diverse environmental and operational parameters—such as wind speed, ambient temperature, release angle, ground-cover type, and release flow rate—the experiment completed 12 sets of valid release conditions. Results: Given the large data volume, this study focused on presenting the detailed results and analysis of the second release experiment. During this experiment, multiple high-definition cameras were placed on the ground, and gimbaled aerial cameras captured the real-time spatial distribution of the hydrogen cloud from multiple perspectives. moreover, the sensor array recorded the dynamic changes in the hydrogen volume fraction at each measurement point. Based on these data, the liquid hydrogen release process was divided into four characteristic stages—ground spread, buoyant transition, stable plume, and cloud dissipation—and the evolution features of each stage were systematically summarized and analyzed. For the quantitative analysis, the sensor data were used to track the hydrogen cloud movement. Furthermore, this study employed the open-source computational fluid dynamics (CFD) code OpenFOAM to perform three-dimensional, transient numerical simulations under the second experimental condition. The deviations between the simulated results and experimental observations fell within acceptable tolerances. Conclusions: This study not only provides large-scale experimental data on liquid hydrogen leakage in open environments—offering valuable foundational data for subsequent research—but also provides robust theoretical support through advanced CFD simulations coupled with empirical experiments. The integrated findings hold considerable reference value and practical importance for advancing the safe, reliable, and sustainable development of the hydrogen energy industry worldwide.