ERI: Stretch Effects on Combustion Characteristics of Flames with Non-Uniform Curvature

The University Corporation, Northridge, Northridge CA

Investigators

Abstract

From the flame of a match to state-of-the-art power and heat generation systems, combustion is ubiquitous in the world economy. Despite its prevalence, the complexity of the underlying processes in a flame still represents a challenge for scientists and engineers, especially considering the need for more stringent regulations for harmful emissions, uncontrolled fires, and climate change mitigation. To simplify the analysis of practical burners, it is common to employ reduced sets of physical and chemical processes retaining essential characteristics of the overall phenomenon. However, such an approach often oversimplifies relevant combustion attributes by neglecting the effect of curvature and stretch inherent to real-world flames. Therefore, the primary goal of this project is to provide a deep understanding of the influence of topography and stretch on combustion and sooting characteristics of non-uniformly curved flames. Results from the proposed investigation will generate data for combustion model development and validation to advance power and heat generation technologies to sustain U.S. energy security using clean fuels and its position as a global leader in sustainability. The project will also allow students from CSUN, a Master’s Hispanic Serving Institution, to participate in cutting-edge research and develop skillsets critical for preparing the future workforce in science and engineering. The proposed work will detail the effect of topography and stretch of non-uniformly curved non-premixed flame structures in their combustion and sooting characteristics. To this end, this project will study stretched curved flames to provide: (1) novel non-premixed counterflow configurations with non-uniform curvature; (2) experimental data detailing stretch and non-uniform curvature influence on the flame structure, stability, temperature, soot formation, and extinction; (3) a simplified theoretical framework for the description of stretched non-premixed flames with non-uniform curvature. New non-premixed opposed-flow experimental burners employing quadric surfaces, and combinations thereof, will be developed to produce flame topographies equivalent to those observed in flame elements from practical combustion systems. Particle image velocimetry will be used for fluid flow characterization, whereas soot and thin filament pyrometry will be employed to determine soot formation and flame temperature. Simplified reacting flow models based on potential flow solutions and infinitely fast chemistry will be developed to describe curvature effects on overall flame characteristics theoretically. The analysis and configurations proposed in this project will allow a better understanding of curvature and stretch influence on flame phenomena. 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.