Assessing the importance of multicomponent transport properties using direct numerical simulations of premixed, turbulent flames

摘要

Implementing multicomponent diffusion models in numerical combustion studies is computationally expensive due to the challenges involved in computing diffusion coefficients. As a result, mixture-averaged diffusion treatments are used to avoid these costs. However, to the authors' knowledge, the accuracy and appropriateness of the mixture-averaged diffusion models has not been verified for three-dimensional turbulent premixed flames. This study will evaluate the role of multicomponent mass diffusion in premixed, high-Karlovitz n-heptane flames, neglecting secondary Soret and Dufour effects. Direct numerical simulation (DNS) of these flames is performed by implementing the Stefan-Maxwell equations in NGA. One-dimensional simulations of premixed hydrogen and n-heptane flames are performed and compared to matching cases in Cantera to verify this method. Premixed, two-dimensional, unstable hydrogen and three-dimensional, turbulent, hydrogen flames are simulated and compared to previous mixture-averaged DNS results. The focus is placed on local and global burning parameters, such as burning velocity, fuel consumption, and flame curvature. Simulation conditions are carefully selected to match previously published results and ensure valid comparison.