Numerical study on rotating detonation combustion with the discrete distribution of partially pre-vaporized n-heptane sprays

Abstract

The rotating detonation engine (RDE) is a novel aerospace propulsion device, with liquid fuel playing a pivotal role in enabling the practical implementation of the RDE. The Eulerian-Lagrangian simulation is used to analyze a two-dimensional rotating detonation combustion with partially pre-vaporized n-heptane sprays. The investigation aims to examine the influence of various inlet area ratios (ψ) on both the droplet evaporation and rotating detonation combustion within the combustion chamber. The findings indicate that a smaller ψ is advantageous for droplet evaporation within the fuel filling area, and the droplet traverses sequentially through the acceleration layer, the deceleration layer, and the re-acceleration layer within this region. With a relatively large ψ, a burned gas bump becomes evident on the deflagration surface, augmenting the evaporation rate of droplets within its proximity. The droplet continues to accelerate within the fuel filling area, while its velocity remains low at the burned gas bump. Furthermore, spot-like diffused flames emerge subsequent to the RDW, with their area expanding to the increase in ψ. Meanwhile, the average heat release rate (HRR) and thrust within the combustor of the rotating detonation engine (RDE) demonstrates diverse oscillation patterns in response to changes in ψ. In this study, when the inlet area ratio is around 0.6, the RDE obtains the most stable average HRR and thrust.