Combustion Characteristics of Pressurized Swirling Spray Flame and Unsteady Two-Phase Exhaust

The effects of flame enclosure and combustor pressure on the combustor flowfield and structure of turbulent spray flames have been investigated. The exhaust jet from the combustor was directed into water to simulate underwater propulsion applications. Two-phase interactions between the exhaust jet from the pressurized combustor and liquid water in an attached mixing chamber have been examined to address issues associated with the operation of a submerged combustor for underwater propulsion applications. Enclosure of the flame, in the absence of pressurization, was found to affect the flame structure and dynamic behavior significantly. At normal pressure, the combustor flow attached to one side of the exit port to result in large-scale, low-frequency flame oscillations. In contrast the pressurized flame, obtained by constricting the exhaust flow from the combustor, was not found to display the same large-scale distortions associated with the enclosed, unpressurized case. The global structure of the pressurized and unenclosed flame cases was similar; however, the flame in pressurized case was found to be shorter. Axial and radial velocities of the air flowfield in the combustor were examined using particle imaging velocimetry. The interaction of the gaseous combustor exhaust jet with water in a downstream mixin