The effect of swirl and combustion are presented to determine the flow dynamics of a fuel-lean direct injection (LDI) configuration under unconfined non-burning and combustion conditions. Specifically, the effect of radial distribution of combustion air swirl in a burner is examined under non-burning and burning conditions using propane as the fuel. The study explores the swirl flow interaction with the use of an experimental double concentric swirl burner that simulates one swirl cup of a practical gas turbine combustor. Three-dimensional (3-D) flowfield data has been obtained immediately downstream of a double concentric swirl burner exit using PIV, to determine the flow dynamics associated with the flow under fuel-lean direct injection (LDI) conditions. Propane fuel was injected radially into the surrounding swirl flow. Flow characteristics of the resulting flowfield, both without and with combustion have been obtained for co- and counter-swirl distributions to the combustion air flow under unconfined environment. Flat vane swirlers have been used to induce swirl to the air flow. Both combustion and swirl distribution significantly influences the resulting flowfield. The 3-D data also allows one to determine the local swirl number of the resulting flow. Results show that swirl distribution in the burner and combustion has significant effect on the characteristics of the internal and external recirculation zones. The heat release from combustion enhanced the inner recirculation zone by increasing its width and length. Combustion increased the magnitude of the vorticity and provided enhanced symmetry to the flowfields. The calculated local swirl number differs under non-burning and combustion cases. They also differ from that estimated using available geometrical relationships that are derived from the swirl vane angle and swirler dimensions only. Combustion enhanced significant increase in velocity magnitudes than that for the no combustion conditions. The entrained mass flowrate is larger for the co-swirl distribution cases and this entrainment is further enhanced with combustion. The results provide the role of radial swirl distribution and combustion on the mean and turbulence characteristics of flows for two varying shear conditions between the inner and outer flow of the burner, thus providing insightful information on the flow dynamics in complex swirl flowfields in addition to providing data for model validation and model development.

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