509 高強度乱流における水素・空気予混合火炎の構造(熱工学)

Abstract

Direct numerical simulations of hydrogen-air turbulent premixed flames propagating in two-dimensional homogeneous isotropic turbulence are conducted to investigate the effects of turbulence length scale on the structure of turbulent premixed flames. Detailed kinetic mechanism including 12 reactive species and 27 elementary reactions is used to simulate H_2-O_2-N_2 reaction in turbulence. DNS are conducted for the cases of turbulence length scale of 1.00, 2.42, 4.84 and 7.26 times of the laminar flame thickness under the constant turbulence intensity. With the decrease of the turbulence length scale, particular flame structure can be observed in which distributions of heat release rate and major radicals such as H, O and OH show relatively smooth profiles whereas those of temperature, density and minor radicals show complicated patterns in the flame front. These local flame structures seem to represent the regime of well stirred reaction zone in the turbulent combustion diagram. The local flame elements in turbulence were identified by using local maximum temperature gradients and statistics of turbulent premixed flames are investigated.