Numerical investigation of unconfined hydrogen explosions using an embedded large eddy simulation (ELES) approach with detailed chemical reaction mechanisms

This paper presents the development of an innovative Embedded-Large Eddy Simulation (ELES) numerical approach incorporating detailed chemical reaction mechanisms with a polyhedral meshing approach to enhance the understanding of explosion dynamics. ELES with detailed reaction mechanisms emerges as a hybrid model that ensures the balance between accuracy and computational efficiency in complex explosion scenarios. This research uses small-scale soap bubble experiments with two ignition methods to assess the effect of ignition source, validate numerical models, and evaluate explosion overpressures. The evolution of the flame, flame speed, and species is analysed, revealing the dynamics of intermediate species in the explosion process. The ELES model predicts peak overpressure with a mean absolute error ranging from 0.1 to 1.87 kPa compared to experimental results while maintaining computational efficiency. The numerical model was also validated for predicting overpressures in large-scale hydrogen-air explosions. This approach provides an effective framework for hazard assessment and safety strategy development, contributing to improved safety protocols and infrastructure design in hydrogen industries. • Zonal LES approach, polyhedral meshing, and detailed chemistry used in the CFD model. • The validated CFD model reproduced the explosion characteristics in experiments. • Ignition source affects overpressure, but blast wave behaviour stays consistent. • The model captured flame behaviour, extending 40 % beyond the initial radius. • Species evolution analysis highlighted the dynamics of active species in explosions.