The propagation characteristics of particle-laden two-phase detonation waves in pyrolysis mixtures of C(s)/H2/CO/CH4/O2/N2

Abstract

In this paper, numerical simulations are carried out to study the propagation characteristics of detonation waves in carbon particle-laden two-phase pyrolysis mixtures consisting of C(s)/H2/CO/CH4/O2/N2. The results show that the hydrodynamic thickness of the detonation waves changes non-monotonically with the carbon particle mass loading ratio and particle diameter. Both the aerodynamic relaxation time and heterogeneous reaction time increase drastically by enlarging the carbon particles. Small particles with the diameter of less than 1 μm gather and then react near the detonation front, which significantly enhances the propagation velocity of the detonation waves. Under such conditions, the aerodynamic relaxation time scale is smaller than the detonation wave characteristic time scale, which causes both the velocities and temperatures of gas and particles to reach the maximum values at the detonation front. However, such effects diminish gradually as the particles enlarge in size. The investigations show that 50 μm-sized particles have almost no effect on the detonation wave, for which the aerodynamic relaxation and heterogeneous reaction time scales are considerably larger than the detonation wave characteristic time scale. The propagation velocity of the detonation wave in the presence of 50 μm-sized particles is close to the value of the gaseous case. The results also show that increasing the particle mass loading ratio induces nonlinear changes in the detonation propagation velocity, due to changes in the global equivalence ratio of the two-phase mixtures.