预混预蒸发正庚烷湍流火焰结构的实验研究

A modified piloted premixed jet burner(PPJB)was used to study the turbulent flame structure of premixed prevaporized n-heptane/air mixtures with an initial temperature of 400 K in the thin reaction zone. The non-reacting turbulent flow field was calibrated by hot wire anemometer(HWA). The reaction zone structure was captured by CH-planar laser-induced fluorescence(CH-PLIF)measurement. The turbulent flame structure characteristics were measured by resonant OH-PLIF. Results show that the thickness of the reaction zone is about 1.6 times that of laminar flame，which is not remarkable when 3D effect is taken into consideration. It supports the applicability of the thin reaction zone theory to prevaporized liquid fuel turbulent flames. The increase of flame wrinkling ratio and turbulent burning velocity fails to match the increase of turbulent intensity. By analyzing the flame curvature and mean flame surface density(FSD)，it is found that the scale，size and number of wrinkles hardly vary in highly turbulent conditions. On the one hand，turbulence may dampen the difference caused by nonequilibrium diffusion；on the other hand，the underestimate of flame wrinkles is more likely due to the incomplete capture of wrinkles structure and the neglect of 3D effect.