Effects of gas velocity, pressure rise, and radiative heat loss on turbulent burning velocities of premixed CH₄/air flames in intense isotropic turbulence

General correlations of turbulent burning velocities (S_T/S_L) over greater parameter ranges than hitherto measured, where S_L was the laminar burning velocity were proposed. Effects of gas velocities ahead of propagating turbulent flames, pressure rise in the cruciform burner, and radiative heat loss on S_T/S_L of premixed CH₄-air flames were presented. These turbulent flames, upon propagation, experienced small acceleration/deceleration with about the same magnitude near the upper/lower portions of the central uniform region, and gas velocities there which were < 5∼10% of turbulent flame speeds depending on turbulent intensities (u′/S_L can be neglected due to the cancellation. At the same S_L = 10 cm/sec and u′/S_L = 18, lean CO₂-diluted or N₂-diluted CH₄ flames have respectively higher, 3.6 or 1.8 times more, values of S_T/S_L than rich CO₂-diluted or N₂-diluted CH₄ flames. These results demonstrate the importance of radiative heat loss on S_T for premixed turbulent combustion. This is an abstract of a paper presented at the 30th International Symposium on Combustion (Chicago, IL 7/25-30/2004).