Simulation exploration on the interaction between hydrogen/air explosion overpressure and flame morphology under different initial pressures

Abstract

This work explores the flame morphology, pressure field, and velocity field near the flame surface in H${}_2$/air explosion under different initial pressures, by resorting to numerical simulations. Their interaction effects are revealed and analyzed in detail, which is hard in real-constrained experiments. The results demonstrate that the flame wrinkling factor increases along time in the magnitude of $n$-degree power. The correlation between its temporal rise rate and initial pressure can be reflected by power function. In addition, it can seen that the trend of wrinkling factor with time is similar to that of explosion overpressure at different equivalence ratios. When the wrinkling factor reaches maximum, the rate of pressure rise is biggest. Like flame surface, the isobaric surfaces near the flame surface also wrinkle. Many concave pressure waves appearing after the convex flame surface disturb the flow in burnt zone. Moreover, it can be found that along time, the increasing pressure difference before and after the flame surface will lead to gas decelerating and then reversely accelerating. When the overpressure increases more quickly, the backward gas velocity goes up faster. Note that the backward velocity after convex flame surface is larger than that after concave flame surface.