The Effects of Flame Stretch on Outwardly Propagating Flames

The effects of flame stretch on an outwardly propagating flame are considered experimentally for both laminar and turbulent flames. Although the thermo-diffusive mechanism caused by the flame/stretch interaction is well known for laminar flames or for weakly stretched flames, recent studies have shown that it influences the local and global flame structures of turbulent premixed flames which consist of strongly stretched flamelets. In this study, outwardly propagating flames of methane and propane mixtures, which are representative of light and heavy hydrocarbons, respectively, over a wide range of equivalence ratio, are used in the application to engine combustion. The primary objective of the present study is to investigate both laminar and turbulent burning velocities experimentally and to discuss the underlying mechanisms in consideration of interaction between flame stretch and the Lewis number.