The ability of electric fields to modify the behavior of hydrocarbon flames is well-known since the first decades of the 20th century. Even weak electric fields can provide significant energy to ionized species, that are naturally produced inside a flame, and modify the behavior of a burning mixture. Over the years, it has been experimentally demonstrated that imposing an electric field it is possible, for instance, to augment the laminar premixed-flame speed, to extinguish liquid-pool fires and jet diffusion flames, to induce instabilities in premixed flame, or to vary lift-off heights of jet diffusion flames. However, this technology has never been utilized outside a research laboratory, mainly because the knowledge of the fundamental phenomena involved in electrified flames is still insufficient to formulate predictive models necessary to effectively design a flame control system.
Although the recent strive to use renewable energy sources, the combustion of hydrocarbons is still one of the main sources of energy for our society. The need to push the envelope of the current state of the art toward more green and efficient technologies constantly faces the limitations posed by combustion instability. In this context, experimental studies have shown that the application of an external electric field is an economic and efficient way of extending the stability limits of a flame. This technique of controlling a combustion process is particularly interesting from an industrial point of view is its ease of implementation in existing combustion chambers and the low amount of electric energy required to operate the system.
This project numerically analyses electrified methane-air flames impinged by an external electric field. The main objective of this analysis is to shed light on the fundamental physics involved in the electric-field/turbulent-flame interaction. By using high-fidelity calculations and some of the most recent supercomputers in the World, the analysis carried out in this project will be able to access details of turbulent electrified flames that are not measurable with experiments. Moreover, a new open-source solver and models for the numerical analysis of electrified flames have been developed and released.
The results of this project have shown that turbulence can create significant fluctuations in the electric charge field produced by a flame. The presence of these fluctuations influences the distribution of the electric force exerted on the flow and consequently the ability of electric fields to control combustion. The dominant challenges in modeling the underlying phenomena have been identified and will be addressed in future works.
