Combustion Waves and Flame Stability in Nanocomposites

Combustion in nanocomposites involves intricate coupling between chemical reactions and transport phenomena across multiple scales and phases, complicating the development of unified theories. In this study, we present a theoretical and experimental framework that can serve as the foundation for a unified theory of combustion wave dynamics and instabilities in nanocomposites. Using high-speed microscopic imaging, the flame morphology and combustion wave behavior are characterized across a range of reactivity levels. We find that wave speed correlates more strongly with reactivity than predicted by classical laminar flame theory but also decreases due to combustion instability when reactivity exceeds a certain level. We reveal that this strong correlation is attributed to heterogeneous flame structures altered by nanoparticle sintering. Unstable combustion waves feature highly corrugated flame fronts that are prone to quenching from significant heat loss in sintered nanoparticles. We further validate wave stability analysis for unseen particle morphology using macroscopic observations. These insights lay the groundwork for theory-guided strategies to control combustion wave behavior and enable the design of reactive nanocomposites that move beyond empirical trial-and-error methods.