Capturing the impact of realistic multicomponent fuels in high-pressure spray combustion simulations

Marquette University, Milwaukee WI

Investigators

Abstract

Soot is one of the most harmful pollutants generated during combustion, as it is associated with cancer, lung disease, and vascular disease, and contributes to climate change. Understanding the fundamental processes that lead to soot formation in gasoline, diesel, and jet engines is necessary for reducing soot emissions. Liquid transportation fuels are composed of hundreds of chemical species, and it is known that certain species have an outsized effect on soot formation. By creating a state-of-the-art combustion simulation that accounts for the complexities of multicomponent fuel droplets in high-pressure engine environments, this project will generate fundamental knowledge of the impact of realistic fuel composition on soot formation. This will advance the field beyond current understanding, which is based on oversimplified representations of fuel composition, and will benefit society by contributing to the design of cleaner engines that improve public health and reduce environmental damage. The project will educate and train young engineers and researchers by incorporating the modeling tools, concepts, and findings into undergraduate and graduate courses and by supporting mentoring for undergraduate and graduate students. The goal of this project is to understand the mechanism by which liquid transportation fuels, which are composed of hundreds of species, generate soot in high-pressure engine environments. The approach is to create a state-of-the-art simulation tool for spray combustion that incorporates a novel, accurate, efficient, and flexible model for multicomponent droplet vaporization. In contrast to the prevailing surrogate approach, which represents a complex fuel using several discrete species, the proposed method employs a continuous thermodynamic framework for the liquid fuel droplets and then computes an adaptive surrogate vaporization flux composed of a few discrete species. The open-source solver will also include advanced models for turbulence-chemistry interactions and turbulence-radiation interactions. Following validation, the simulation will be used to evaluate the hypothesis that spatial variations in aromatic concentrations caused by preferential vaporization play a key role in soot inception. The combination of high-fidelity models will be used to improve fundamental understanding of the impact of real multicomponent fuels on soot formation in high-pressure spray combustion. In the future, the simulation tool can be used to study the impacts of conventional and alternative fuels on phenomena like lean blowout, auto-ignition, and the emission of other pollutants. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.