Wed, Sep 04, 2019 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Basile Radisson, USC
Talk Title: Insights into the Nonlinear Evolution of Flame Fronts through Experiments and Models
Abstract: Due to the exothermicity of combustion reaction, premixed flames are intrinsically unstable. Consequently, cellular patterns are formed on the flame front resulting in rich and complex dynamics. Combustion involves several hundreds of elementary chemical reactions occurring at a submillimetric interface, rendering a detailed description computationally intractable. Simplified models offer much insight into these complex dynamics. Through asymptotic analysis, the shape of the flame front can be described by a set of poles and their dynamic evolution in the complex plane. Here, we demonstrate for the first time the validity of such model in comparison to experimental flame evolution. A premixed flame propagates in a reactive mixture held between two vertically oriented ceramic glass plates separated by a 5mm gap. By extracting a flame front from this experiment, we demonstrate the feasibility of describing the shape of the front by a set of pole solutions. The flame front dynamics are well described for approximately ten times the characteristic time of the instability. Beyond this time, the comparison is limited by the sensitivity to initial condition. However, by studying statistical properties of the flame front, here statistics of cell sizes, we demonstrate that the pole description is still valid at long time. Moreover, these statistics satisfy a gamma distribution, characteristic of phenomena for which the elementary interaction rule is of additive nature and which results here from the pole to pole attraction. This analytical prediction of the cell-size distribution could be of great interest for the understanding of turbulent flame dynamics.
Biography: Basile Radisson is a postdoctoral scholar in the Aerospace and Mechanical Engineering department at the University of Southern California since June 2019. Prior to joining USC, Basile received his PhD from IRPHE, AixMarseille Universite, France, working on flame front dynamics under the supervision of C. Almarcha and B. Denet. His research interests lie in instability phenomena driven by geometric nonlinearities. He is currently working on snap instabilities in fast elastic filaments under the supervision of E. Kanso.
Location: SLH 102
Audiences: Everyone Is Invited
Posted By: Tessa Yao