Simulation of obstacle spacing effects on premixed hydrogen-air explosion dynamics in semi-confined spaces

In complex industrial environments, obstacles are widely present with significant variations in spacing, and their impact on gas explosion propagation characteristics is a critical issue in safety protection design. This study employs Large Eddy Simulation to systematically analyze the effects of obstacle spacing on the dynamics of premixed hydrogen-air explosions in a semi-confined space. The findings indicate that flame propagation velocity is significantly influenced by self-acceleration effects and turbulent wall disturbances at low spacing coefficients (0.2, 0.4, 0.6). In contrast, at medium (0.8, 1.0) and high (1.2, 1.4, 1.6) spacing coefficients, the velocity is predominantly affected by turbulence induced by the obstacles, generally increasing as obstacle spacing widens. A critical effect on peak overpressure and pressure rise rate is observed near a spacing coefficient of 1.0. When the spacing coefficient increases from 0.2 to 1.0, the peak overpressure rises from 54.82 kPa to 155.17 kPa; beyond 1.0, overpressure exhibits only slight fluctuations within a 5.47 kPa range. A complex coupling relationship is found between the spatial distribution of turbulence, flame propagation, and pressure accumulation, showing distinct critical characteristics at a spacing coefficient of 1.0. This study provides important insights for the protective design of hydrogen explosion mitigation in semi-confined spaces.