Study on shock wave propagation behavior and induced spontaneous combustion characteristics in high-pressure hydrogen leakage under varying discharge conditions

Abstract

[Objective] Hydrogen, being a clean and efficient energy source, holds significant potential in addressing challenges like energy shortage. However, its inherent high risk of fire poses a major obstacle to its broader applications. [Methods] A high-pressure hydrogen leakage model based on shock tubes was developed for this study, by integrating a large eddy simulation model, eddy dissipation conceptual model, instantaneous rupture model, and a 21-step detailed hydrogen-air chemical reaction mechanism. With varying discharge conditions of high-pressure hydrogen, such as discharge pressure, tube diameter, and tube geometry, this study investigated the propagation characteristics of shock waves in shock tubes. It introduced the concept of the average intensity of leading shock waves and explored the law of spontaneous combustion induced by shock waves in shock tubes. Moreover, the influence of varying leading shock wave intensities on the extent of hydrogen and oxygen mixing was analyzed. [Results] This study revealed that a larger tube diameter resulted in a reduced intensity of shock waves and a slower propagation velocity inside the shock tubes. Furthermore, increasing the discharge pressure led to higher intensity and propagation velocity of shock waves, resulting in a more distinct reticulated structure of shock waves inside the tubes.The downstream tube geometry had a significant impact on the behavior of shock waves. Specifically, a larger non-acute tube angle caused a decrease in pressure following the first reflected shock wave. Moreover, under non-spontaneous combustion conditions, there was a positive correlation between shock wave intensity and the increase in hydrogen mole fraction, as well as the decrease in oxygen mole fraction. Under spontaneous combustion conditions, the increase in shock wave intensity corresponded to a narrower increase in hydrogen mole fraction and a more significant decrease in oxygen mole fraction, attributed to the combined effects of combustion consumption and shock wave mixing.[Conclusion] The findings of this study present significant scientific insights for a better understanding of the spontaneous combustion mechanism associated with high-pressure hydrogen leakage. Based on these results, further research is recommended to develop a prediction model for spontaneous combustion under high-pressure hydrogen leakage, considering multiple characteristic parameters. Additionally, it is advised to focus on the development of technologies aimed at suppressing spontaneous combustion. These research endeavors collectively aim to ensure the safe storage and application of hydrogen.

Keywords

• high-pressure hydrogen
• leakage
• spontaneous combustion
• tube structure
• shock wave
• numerical simulation