microexplosions

Microexplosions are rapid, localized energy releases within a small volume that cause abrupt fragmentation or violent ejection of material. They are most often observed in liquid droplets containing two immiscible or highly volatile components, where internal vaporization creates enough pressure to rupture the droplet.

In spray combustion research, a common scenario involves a fuel droplet with a more volatile phase. Upon heating or exposure to hot air, the volatile component boils inside the droplet, forming a vapor bubble that grows rapidly and leads to internal rupture and secondary atomization into smaller droplets. This internal fragmentation increases the surface area available for combustion and can affect mixing, burnout, and emissions.

Other mechanisms include trapped gases within porous solids or emulsions that experience rapid phase change. Microexplosions can also arise from cavitation or flash boiling when a liquid experiences a rapid pressure or temperature change. The resulting pressure surge causes sudden fragmentation or ejection of material from the affected region.

Observation and analysis of microexplosions typically rely on high-speed imaging, advanced lighting, and sometimes spectroscopy to resolve the timescales, which are often in the microsecond range, and to characterize the resulting fragment size distribution.

Applications and implications vary by context. In internal combustion engines, microexplosions can enhance atomization and mixing but may also influence flame stability and emissions. In materials processing or encapsulation technologies, controlled microexplosions can affect fragmentation behavior or trigger the release of contents in a precise, rapid manner. The phenomenon is studied across fluid dynamics, combustion science, and materials engineering to understand mechanisms, predict outcomes, and optimize processes.