Development of kinetic models for the hybrid fuels combustion containing aluminum particles

Recent studies identified the addition of metal particles into conventional liquid fuels (jet fuel, gasoline, diesel) as one possible strategy to increase fuel energy density and specific impulse. The objective of this work is to evaluate the combustion potential of hybrid fuels by developing detailed chemical mechanisms to model their behavior. Thus, this work is focused on 1) identifying the key parameters that control the promoting/inhibiting effects of aluminum on jet fuel combustion and 2) the assessment of the impact of 1% (weight) of passivated aluminum on the main combustion parameters (combustion temperatures, ignition delays, laminar flame speeds). This study considers the combined effects of aluminum and alumina on combustion properties based on the ratio of their mole fractions. The analyses of the mechanism revealed 1) the origin of the promoting/inhibiting effects on combustion and 2) that the hybrid fuel combustion exhibits a three-stage reactivity, whereas the conventional jet fuel presents only one. This work proposes a first detailed kinetic mechanism for hybrid fuels combustion. Moreover, the numerical results obtained in this wide parametric study evidence that hybrid fuels must be used in fuel-rich regimes at low temperatures (T < 800 K) to maximize their combustion performance.