The three-dimensional flame-holding mechanism in a gun-type burner has been investigated, as well as the fuel droplet dynamics. This gun-type burner forms a recirculating swirling flow with a complex structure, essential for understanding the flame-holding mechanism. The swirl flow will increase fuel–air mixing, improve flame stabilization, and prevent flame attachment on the baffle plate.

The central plane of the burner has been analysed in reacting and non-reacting conditions by means of stereoscopic particle image velocimetry. This technique allows the measurement of the full three-dimensional velocity vector map in a fluid plane. A complex swirl motion has been found for the reacting condition, with the formation of a couple of twin vortexes in the shear flow region that surrounds the recirculation areas. The influence of changing the airflow rate (λ) has been studied. The strongest effect found concerns the axial and radial components, while the swirl component is hardly influenced.