Modelling and simulation of hydrogen leakage and buoyant rise inside an aircraft compartment for the identification of ventilation power requirements

Abstract

Climate change, driven by the extensive use of fossil fuels, necessitates a shift towards sustainable energy sources to mitigate environmental impacts. Hydrogen has emerged as a promising solution due to its potential for zero-emission energy production. This thesis specifically addresses the behaviour of hydrogen in the event of leakage, focusing on dispersion patterns and ventilation requirements to ensure safety. A high-fidelity simulation framework is developed using ANSYS software to model hydrogen dispersion, assess flammability risks and evaluate ventilation effectiveness. This study aims to determine the minimum ventilation power required to manage hydrogen leaks and provide insights into designing safe and efficient hydrogen storage systems. By contributing to the understanding of hydrogen integration in aviation, this research supports the broader objectives of the DLR-internal project called “H2EAT” and aligns with the climate goals of the European Union for sustainable aviation. A comprehensive investigation into the behaviour of hydrogen within a confined compartment during leakage events is presented in this thesis, with a particular focus on its interactions with air. The research involves a detailed comparative analysis of two advanced simulation models, the Volume of Fluid (VOF) model and the species transport model, to evaluate their capabilities in accurately representing the complex dynamics of gas-gas interactions. By examining how these models capture the dispersion, mixing and stratification of hydrogen in the presence of air, the goal is to determine which approach provides a more reliable depiction of the physical phenomena involved. In addition to the modeling work, the critical aspect of safety management in hydrogen leakage scenarios were addressed in this thesis. Specifically, it explores the ventilation requirements necessary to mitigate the risks associated with hydrogen accumulation in confined spaces. Through transient simulations, the research assesses the effectiveness of different ventilation strategies in regulating hydrogen concentrations, ensuring that the environment remains safe during and after a potential leakage event. This investigation aims to contribute valuable insights into the design and operation of safety systems in hydrogen-related applications particularly, when precise control of gas behaviour is essential.