Affiliations: Department of Mechanical Engineering, Yamaguchi
University, Ube, 755-8611, Japan
Abstract: Vortical and thermal structures of non-premixed propane flame in a
bluff-body burner are studied experimentally in the transition from laminar to
turbulent flow. In particular, we focus attention on the effect of annular air
flow on the flame. The small-scale inner vortices inside the flame is
stimulated by the annular air flow, and outside the flame, small eddies due to
turbulence rather than the large-scale outer vortices due to thermal buoyancy
become dominant with increasing air velocity. The interrelation between the
vortical and thermal structures is analyzed by looking at the frequency
spectrum and probability density function of temperature fluctuations.