Effect of Aluminum particles on hybrid H2–Air Detonations

During spacecraft landings, rocket exhaust interactions with regolith can trigger particle combustion, potentially leading to explosions. At the same time, these granular particles could serve as an untapped energy resource for propulsion. This study investigates hybrid detonations involving reactive aluminum (Al) particles in gaseous fuel–oxidizer mixtures. An unsteady compressible in-house Eulerian–Eulerian solver, HyBurn, is used to model gas–particle interactions using implicit LES and a low-Mach adjustment to the Riemann solver. The Al particle oxidation model is based on the works of Benkiewicz and Hayashi, and the H₂ reactions are modeled using the O’Conaire mechanism. A 2-D rectangular channel of width 10 mm is used to simulate Al–H₂–air detonations with monodisperse (1μm) Al particles of concentration Φ_Al = 0.5, and varying H₂ concentrations (Φ_H2 ). The addition of Al particles is observed to enhance mixture reactivity and reduced detonation cell sizes. For Φ_H2 = 1, H₂–air mixture, the presence of particles reduced cell sizes, increased the H₂ heat release rate and Chapman–Jouguet velocity, D_CJ , from 1950 m/s[5] to 2110 m/s. The H₂ heat release rates for cases with particles exhibited trends similar to the particle-free cases, except the presence of particles shifted the maximum H₂ heat release rate occurred from Φ_H2= 1.0 toΦ_H2 = 0.8. The presence of Al particles altered the detonation limits in this channel from Φ_H2 = 0.8–1.9 without particles to Φ_H2= 0.5–1.1 and also led the fuels (H₂ and Al) to compete for the limited amount of O₂. Double-shock structures with distinct reaction zones for H₂ and Al are observed for detonations of mixtures with particles. The strength of the secondary shock diminishes with increasing hydrogen concentration in the mixture. The nature of the competition, favorable conditions for the fuels, and other observations from the simulations are being analysed.