Effect of Activation Energy on Detonation Cellular Dynamics and Reinitiation Behaviors

Abstract

Listen

Translate article

Two-dimensional simulations of detonation propagation in a channel filled with stoichiometric hydrogen–air mixture with unity Lewis number using the chemical-diffusive model (CDM) coupled with compressible Navier–Stokes equations are presented. Specifically, the effect of four activation energies (E=2,4,6, and 10) with CDM on detonation cell structures, cellular dynamics, and reinitiation behaviors is discussed. As E increases, detonation cell size increases and the cellular structure becomes more irregular. Spectral analysis by the auto-correlation function is performed to provide quantitative insights about detonation cell size and irregularity. Furthermore, detailed analysis on the detonation wavefront captures three distinct detonation propagation modes, including stable detonation (E=2), weakly unstable detonation (E=4,6), and highly unstable detonation (E=10). The effect of activation energy in detonation attenuation is further studied through a detonation propagation over a semicylinder obstacle, where two distinct detonation attenuation regimes are captured, including unattenuated detonation transmission (E=2,4) and critical detonation reinitiation (E=6,10). The mechanism of the critical detonation reinitiation event is further examined. It is found that a strong transverse detonation wave forms at higher activation energies after the Mach shock reflection at the bottom wall, which eventually leads to a steady detonation propagation.