Numerical simulation of two-dimensional detonation propagation in partially pre-vaporized n-heptane sprays

In this paper, two-dimensional detonation propagation in partially pre-vaporized n-heptane sprays is studied by using Eulerian–Lagrangian methods. The effects of droplet pre-evaporation on the detonation propagation are investigated. The general features and detailed structures of two-phase detonations are well captured with the present numerical methods. The results show that the detonation propagation speed and detonation structures are significantly affected by the pre-evaporated gas equivalence ratio. The numerical soot foils are used to characterize the influence of pre-evaporated gas equivalence ratio on the detonation propagation. Regular detonation cellular structures are observed for large pre-evaporated gas equivalence ratios, but when decreasing the pre-evaporated gas equivalence ratio, the detonation cellular structures become much more unstable and the average cell width also increases. It is also found that the pre-evaporated gas equivalence ratio has little effects on the volume averaged heat release when the detonation propagates stably. Moreover, the results also suggest that the detonation can propagate in the two-phase n-heptane/air mixture without pre-evaporation, but the detonation would be first quenched and then re-ignited when the pre-evaporated gas equivalence ratio is small or equal to zero.