Measuring and Modeling Droplets in Biofuel Sprays

Reliable sources of energy-dense fuels critical

As energy demands of the US grow, we continue to seek secure, reliable sources of energy-dense fuels for transportation and power generation. Biofuels are one class of potential contributors to our future energy supply, both as pure fuels and as additives to fuels derived from other sources. These fuels are typically injected or sprayed into the combustion chambers of engines where they mix and evaporate in air at high temperatures and pressures before undergoing combustion.

The efficiency of the combustion process and its propensity to produce pollutants depend on the uniformity of the air-fuel mixture to be burned which, in turn, depend on the evaporation and mixing of fuel droplets in fuel sprays. In one of his research areas, Giles Brereton conducts experiments on biofuel sprays in which he processes laser-light signals scattered from many droplets within the spray to deduce the sizes of the droplets and their statistical distribution. In companion studies, Dr. Brereton is developing mathematical models of individual fuel droplets and their evaporation characteristics. With input from experiments of this kind, the authenticity of models of the behavior of biofuel droplets and sprays can be verified. This approach can then be used to describe the behavior of droplets of existing, new, or hypothetical biofuel blends of arbitrary composition. These models can be used to design fuels with prescribed droplet behavior and to describe fuel-droplet behavior in large-scale computer simulations of combustion, which are used to predict pollutant formation and combustion efficiency, and to optimize biofuel combustion-chamber designs.

Dr. Brereton is also engaged in research into the mathematical modeling of turbulence in flows over rough surfaces, forced oscillatory diffusion as a mode of high-flux heat transfer, design of efficient systems for agricultural nutrient and pesticide spraying, and computer generation, grading and provision of feedback for technical questions in engineering educational courses.