Global and local viewpoints to analyze turbulence-premixed flame interaction

Abstract

Turbulence remains one of the most important unresolved problems in classical physics. The addition of exothermicity through a myriad of chemical reactions in fluid turbulence renders turbulent combustion a formidable challenge alongside its ubiquity in all chemical to mechanical energy conversion devices. Here, we review some recent advancements in theory, experiments, and computations of turbulent premixed combustion through two ostensibly decoupled: global and local viewpoints. Global viewpoints are essential to obtain useful statistics of turbulent flame propagation such as turbulent flame speed. Local viewpoints are crucial towards understanding detailed phenomena such as how local flame elements are stretched or annihilated. These fine grained understandings must culminate towards various sub-models of a successful global model. Essential features of recent theoretical developments towards turbulent flame speed using the level set formulation are reviewed here. The theoretical turbulent flame speed is shown to conform to the experimental expanding flame measurements over a wide range of fuels, pressure and turbulence intensity. Finally, recent advances to track flame elements and their local properties from detailed chemistry direct numerical simulations, are reviewed through a Lagrangian viewpoint.