Propylene/air diffusion flame stabilized on a 50 mm diameter burner. Re=1370.

Natural.

High temperature regions are clearly visibile at the base of the burner and near the middle. The region near the base is at high temperatures because of low radiative fractions and the region near the middle is at high temperatures due to the intense burning caused by the vortex induced mixing.

1 msec exposure on 1600 ASA film, with no filters.