Study on the dynamic process of premixed hydrogen-air deflagration flame propagating in a closed space with obstacles

Abstract

This paper investigates the kinetic behavior of premixed hydrogen-air deflagration flame propagation in a closed tube with different obstacle arrangements with the Large Eddy Simulation (LES) technique. Comparing the computational accuracy of four different types of turbulent flame wrinkling models, it finds that the prediction results of the dynamic wrinkling model have a high match with the experimental and theoretical values in quantitative and qualitative terms. Numerical results show that the deflagration flame propagation process in the closed barrier tube has undergone a spherical flame, finger flame, jet flame, vortex flame, and tulip-like flame, five forms of the evolution process. The obstacle center arrangement and all-around arrangement induced the maximum and minimum values of flame propagation speed and deflagration overpressure, respectively; the ratio of the first speed peak, the second speed peak, and the growth rate of overpressure were 1.46, 1.51, and 1.9 times for the two arrangements, respectively. The flame propagation process is mainly influenced by the coupling of Rayleigh-Taylor (R-T) and Kelvin-Helmholtz (K-H) instability mechanisms. Furthermore, a simplified analytical model of hydrodynamic instability is developed, and it is found that instability plays a crucial role in the deformation and acceleration of the flame front.