Vortical Structures in a 2-D Vertical Bluff-Body Burner

Abstract

Vortical structures arc investigated experimentally for combusting flow from a 2-D slot burner. A combination of a fast reactive system producing TiO₂ seed particles and a 2-D sheet lighting method was used to visualize the vortical structures. At a fixed air flow rate, three regimes were observed—depending on the fuel flow. These three regimes depend on whether the fuel penetrates the recirculating zones and are designated as pre-penetration, penetration-transition, and penetration regime. In each regime, the flame and vortical structures are described and vortical shedding frequency is measured. It was found that the “petal” structures observed in a flame consist of vortical pairs of opposite sign. It is believed that these “petals” may be the precursor of flamelets seen in turbulent combustion.