Fundamental understanding of flame extinction plays a central role in promoting energy security, environmental sustainability, air-travel safety and opportune fire suppression. Flame extinction has been extensively studied by the international combustion community in the past few decades, however, the scope of fundamental studies has mostly been limited to gaseous flames. Droplets, such as fuel sprays in aeronautical combustors and water droplets in pollutant reduction or fire suppression, are ubiquitous in practical combustion systems. When interacting with an established gaseous flame, droplets introduce additional mechanisms to extinguish a flame, through physical processes such as vaporization, dilution, subsequent reactions, modulation of turbulence, and radiative heat transfer. Therefore, the principal aim of this project is to provide a fundamental understanding and a quantitative description of key factors governing the flame extinction process in presence of droplets. The project will also encompass significant educational activities, including a new “Virtual Thermal Fluids Lab” course and a companion book that are enabled by the research data. In conjunction with the research and educational activities, two outreach programs will be implemented. First, an educational program for high school teachers will use the research data as a unique avenue to enhance the computational literacy of high school students. Second, researchers will work with local museum curators to showcase artistic designs that are derived from the research program and to attract underrepresented groups into STEM careers.

The goal of this project is to address the knowledge gap pertaining to the mechanism through which heterogeneous heat, momentum, and mass transfer impact the extinction limits for flames. Stochastic droplet-laden turbulent flow introduces additional heat sinks/sources and nonuniform reactivity to the delicate balance near the extinction limit. A canonical counterflow configuration will be adopted to represent the fundamental processes of flame-droplet interactions. An open-source computational framework will be adopted, where numerical algorithms will be carefully designed to ensure necessary coupling between various physical processes. The proposed numerical models and solution algorithms will incorporate latest development from the study of turbulent multiphase flows and extinction chemistry, paving the way for more accurate in-depth computational studies. A methodology will be established to combine information from three-dimensional direct numerical simulations with one-dimensional modeled turbulent simulations to enable efficient and reliable parametric analysis. Using the reduced-order models, scaling relations will be established, which will provide a quantitative description of critical time and length scales in such problems. Successful execution of this project will enable robust reduced-order modeling in engineering applications, such as lean-blowoff in aeronautical combustors and fire suppression using water mists.

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.

Project Start
Project End
Budget Start
2021-09-01
Budget End
2026-08-31
Support Year
Fiscal Year
2020
Total Cost
$394,563
Indirect Cost
Name
University of Connecticut
Department
Type
DUNS #
City
Storrs
State
CT
Country
United States
Zip Code
06269