Modeling Reacting Interfaces for Biomass Combustion using Flame Generated Manifolds

This project will answer the fundamental question of what happens when solids or liquids burn. The burning of any material involves complex heat and mass transfer processes near the fuel surface. These reacting interfaces are commonly found in engineering problems where chemical energy is converted to thermal energy. Examples include biomass heating, solid rocket motors, and internal combustion engines. Mathematical models to describe these interfaces, however, continue to be one of the main challenges in predicting combustion performance. This study focuses on developing new mathematical theories and conducting laser-based measurements to understand the nature of reacting interfaces. The impact of this effort to society is to offer scientific insight in the conversion of fuels to useful energy for power production and heating. Developing accurate models to describe reacting interfaces remain a daunting task in combustion science. The fundamental difficulty is the coupling of thermal and mass transport with chemical reactions at length and time scales that are far smaller than system scales of interest. Compounding these challenges is the response of liquid or solid fuel surfaces, which regress during the burning process and are dependent on local flame structure. To reduce the degree of freedom of the problem, flamelet generated manifolds of the reacting interfaces will be explored in this research. The appeal of the new modeling approach is that it couples important mass and thermal transport processes with detailed descriptions of chemical kinetics, thus allowing for accurate predictions of energy conversion rates and harmful pollutants. The proposed method will be used to predict upward flame spread over both synthetic and natural materials. To validate model predictions, both direct numerical simulation and experiments are planned. The experiments will employ tunable diode laser absorption spectroscopy to probe species composition and temperature near at the reacting fuel surface. The expected short-term impact of the research is to provide a flamelet generated manifold library to the combustion and fire modeling community. The long-term impact of this research is to provide a high-fidelity, broad-based computational tool and experimental techniques to understand and predict the burning of biomass materials.