Modeling of turbulent deflagration behaviors of premixed hydrogen-air in closed space with obstacles

The propagation of premixed hydrogen-air deflagration flames in a closed duct with different shapes of obstacles was investigated using large eddy simulation (LES). The turbulent flame wrinkling factor in the LES subgrid turbulent combustion model is dynamically modeled based on Charlette's power-law model. The LES results obtained by the dynamic flame surface density (DFSD) model can accurately match the experimental data quantitatively and qualitatively. Numerical results show that the triangular obstacle induces a higher peak overpressure, 7% and 30% higher than that in the square and circle, respectively. The formation of juxtaposed tulip flames is discovered, and the topological analysis of the velocity vector field reveals that the vortex at the tail of the obstacle is the main inducing factor for its formation. Additionally, the Karlovitz number is used to quantify the degree of turbulence-flame interaction, and the transition of deflagration flame from wrinkled flame to thin reaction zone is observed. The research helps to un-derstand the mechanism of deflagration flame propagation induced by obstacles and provides critical in-formation for safety planning and explosion protection.(c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.

Automated summary

The study investigates the propagation of premixed hydrogen-air deflagration flames in a closed duct with different shapes of obstacles using large eddy simulation (LES). The turbulent flame wrinkling factor in the LES subgrid turbulent combustion model is dynamically modeled, and the results obtained accurately match the experimental data. The research reveals that the triangular obstacle induces a higher peak overpressure compared to the square and circular obstacles, and the vortex at the tail of the obstacle is the main inducing factor for the formation of juxtaposed tulip flames. The study also observes the transition of the deflagration flame from a wrinkled flame to a thin reaction zone and quantifies the level of turbulence-flame interaction using the Karlovitz number. The findings provide critical information for safety planning and explosion protection.