Combustion processes are omnipresent. The vast majority of the world’s electricity derives from the burning of organic matter – oil, gas, coal, and increasingly, biomass; transportation is driven almost entirely by the combustion of petroleum fuels. Despite its compelling importance, our understanding of fire, and how to control it remains incomplete. The limits of our present knowledge constitute a missed opportunity to better implement one of the most pervasive chemical processes.
Our research program on Flames is focused on exploring and targeting alternative methodologies for the suppression and control of fires. In terms of fire suppression, for example, we are currently focused on two promising approaches: one based on electric fields, the other on powerful acoustic perturbations.
The first approach relies on the fact that hydrocarbon flames are actually chemically driven, non-equilibrium plasmas. As such, they contain large concentrations of charged species (typically, ~1011 charges per cubic centimeter) which respond collectively to externally applied electric fields. Importantly, the movement of ions and electrons in the field can transfer momentum to the surrounding gas though frequent collisions with the neutral species. For sufficiently large fields, this process can result in macroscopic gas flows – so-called ionic or electric wind – with speeds of up to ten meters per second. When placed in the proximity of a flame, the resulting gas flows act in a highly directional manner to rapidly displace the combustion zone from the fuel source.
The second approach provides oscillatory perturbations to the flame with acoustic waves. We are exploring the required acoustic conditions necessary for extinction. Our goal is to understand the fundamental physics and potential applications of using sound to manipulate combustive processes.
We are currently working to elucidate the mechanistic details underlying electric and acoustic fire suppression and to scale these approaches to address larger fires of practical interest. In addition we are exploring a wealth of novel ways to affect and control flames (e.g. focusing the heat of flames).