Quantitative Effects of Porous Obstruction Number on Explosion Dynamics of C₃H₈/H₂ Mixtures

This study investigates the effects of porous obstruction quantity on the explosion dynamics of C3H8/H2 hybrid fuel mixtures in semiconfined pipelines through integrated experimental and numerical approaches. High-frequency pressure transducers and ultrahigh-speed cameras were employed to record overpressure evolution and flame morphology, while numerical simulations incorporating the Charlette flame wrinkling model elucidated turbulence-flame interaction mechanisms. The study compared configurations with sequential porous obstructions to single-obstruction setups, revealing that obstruction number and blockage ratio critically govern flame speed, peak overpressure, and turbulent intensity. Under sequential-obstruction conditions, the flame transitions from laminar to turbulent after passing the first obstacle, exhibiting a 13.8-28.7% velocity enhancement. The second obstruction reduces turbulence effects, and suppression efficiency decays with increasing obstacle count. Overpressure analysis demonstrates that at an 87% blockage ratio, sequential obstructions elevate maximum overpressures at monitoring points PT1 and PT2 by 66.2 and 96.9%, respectively, compared to single-obstruction configurations. The deflagration index migrates toward ignition-adjacent regions, indicating enhanced explosion severity. Numerical validation confirms the Charlette model's precision in predicting flame front dynamics and capturing extreme flow-field variations (Mach number ≤1.00, vorticity peaks ≤40,000 s- 1) between obstacles. This work provides theoretical foundations for hydrogen-mixed gas explosion mitigation and pipeline safety design.