Numerical and experimental investigations of hydrogen-air-steam deflagration in two connected compartments with initial turbulent flow

Turbulence in the hydrogen combustion field influences flame propagation and its consequences, which is of great importance for the safety of hydrogen/nuclear energy systems. The large-scale deflagration experiment of the premixed H2-air-steam cloud with initial high turbulence in the large closed two-compartment system is conducted. The Computational Fluid Dynamics (CFD) tool GASFLOW-MPI developed to assess hydrogen safety during accidents, is utilized here to simulate this experiment. The objectives encompass exploring the numerical and experimental aspects of H2 flame propagation and deflagration consequences with turbulence effect, and validating the CFD code through this experiment. The agreements between the prediction and the experimental data indicate that simulation modeling with the Large Eddy Simulation (LES) turbulence model and turbulent flame speed closure is recommended for investigating the H2 deflagration. The experimental and predicted results indicate the following highlights. 1. The hydrogen flame can propagate in the opposite direction of the gas flow when there is an intense turbulent fluctuation upstream. 2. Turbulence accelerates the combustion velocity, causing the pressure to rise to its maximum in less than 2 s 3. ... mehrSo, the pre-calculation of flow turbulence before ignition and during hydrogen deflagration is essential for predicting flame propagation. 4. The peak combustion pressure increases significantly with the hydrogen concentration in a premixed lean H2 cloud. 5. Convection and radiation contribute comparably to heat loss, leading to a decrease in system temperature and pressure. The long-term hydrogen combustion load is primarily governed by heat transfer and heat dissipation within the structures.