CAREER: Extinction Phenomena in Turbulent Liquid Dual-Fuel Flames

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Turbulent combustion of energy-dense, liquid fuels is at the core of aviation applications. Dual-fuel operation with liquid fuel – hydrogen blends have become a research point of interest. There is limited knowledge from modern experimental studies of complex liquid fuels in highly turbulent reacting flows. The overarching research goal is to investigate extinction-based processes in highly turbulent liquid-fueled flames with hydrogen enrichment and develop new laser diagnostic tools to enable these studies. Educational activities are focused on the addition of combustion physics content to undergraduate and graduate courses and the creation of visual demonstration activities. Learning modules covering combustion and energy science topics will be based on experimental demonstrations designed and built by undergraduate researchers. These demonstrator devices are transportable to classroom settings and outreach engagements. Learning modules will be developed for online sharing, televised delivery with PBS WKAR, and for global access on YouTube.The primary research goal is to investigate extinction-based processes during blowoff at global and local scales in high-Reynolds number, turbulent liquid dual-fuel, hydrogen enriched flames. Particular emphasis will be placed on studying hydrogen enrichment effects on local extinctions in flame structure given varying Le mixtures and potentially inhomogeneous mixing. This study will focus on the dynamics of primarily prevaporized flames in addition to dilute droplet-spray flames, which each have unique dominating thermophysical properties and extinction mechanisms due to interactions between droplets, fuel vapor, turbulence, and flame. The experimental program has been designed to (1) address aspects on coupling between global blowoff transients and local extinction processes, (2) advance new diagnostic methods for CH/formaldehyde PLIF and Rayleigh scattering thermometry in liquid fuel flames, and (3) to capture statistics on flame structure, temperature, scalar dissipation, and curvature that can be incorporated into advanced simulations and modelling via validation-quality datasets. Newly developed diagnostic strategies will be used to observe extinctions in flame structures influenced by turbulence-chemistry interactions due to curvature and Le effects. Measurement of 2-D scalar fields in these flows will provide joint PDF statistics on the temperature, progress variable, and scalar dissipation which has not been experimentally reported for heavier hydrocarbon fuels. The availability of these new tools will allow for insights into previously inaccessible regimes of liquid fuel combustionThis 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.