LES of turbulent swirling flames: a tool for gas turbine combustor simulations

Abstract

Large eddy simulations (LES) of turbulent non-premixed swirling flames with strong emphasis on jet precession, recirculation and vortex breakdown have been investigated. LES techniques have been applied to predict several flames based on the Sydney swirl burner experiments. We solve numerically the governing equations for continuity, momentum and mixture fraction on a structured Cartesian grid, along with the Smagorinsky eddy viscosity model with dynamic procedure as the subgrid scale turbulence model. Finally, the conserved scalar mixture fraction based thermo-chemical variables are described using the steady laminar flamelet model. Results show that LES successfully predicts both the upstream first recirculation zone generated by the bluff body and the downstream second recirculation zone attributed to the vortex breakdown. Generated frequency spectrums demonstrate low frequency oscillations and the existence of precession in the centre jet which agrees very well with the experiment. The scalar predictions are also successful at the most axial locations away from the inlet. Additionally, the study further highlights the predictive capabilities of LES on jet precession with the laminar flamelet model providing a good technique for capturing the basic swirling flame structure.

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Identifiers

ORCID for K.K.J. Ranga Dinesh: orcid.org/0000-0001-9176-6834

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