Numerical simulation of detonation re-initiation in a 90° bifurcated channel filled with n-heptane/air mixture

Abstract

This paper aims to study the detonation re-initiation through multiple reflections when the detonation enters the horizontal channel holding liquid fuel from the vertical branch. Based on the Eulerian-Lagrangian method, the detonation diffraction, reflection and re-initiation of gas phase (C7H16/Air) and two-phase (n-heptane/Air) are compared, and the effects of droplet diameters on re-initiation and the interaction between shock wave and droplets are analyzed. The results show that compared with the detonation propagating in pure gaseous mixture, detonation is easier to be decoupled in two-phase mixtures during the diffraction stage due to the droplet fragmentation and evaporation process, and lots of unburned fuels are left behind the detonation wave. As the droplet diameter increases, the detonation wave propagates slower and the cell size increases. The number of transverse waves formed after the first reflection gradually decreases, and the transverse detonation in mixture with larger droplets is decoupled during the downstream propagation. The shock wave interacts with the droplet, leading to the occurrence of droplet breakup. At this stage, the total mass of the droplets remains basically unchanged. After that, the droplet evaporation process occurs, and the droplet mass decreases rapidly.