Numerical investigation of turbulent swirling flames with validation in a gas turbine model combustor

Abstract Numerical investigation of turbulent swirling flames is performed in a model gas turbine combustor. The calculations are performed using the CFD code OpenFOAM. Large Eddy Simulation (LES) approach based on the Smagorinsky model is used as the main turbulence modelling strategy, whereas Unsteady Reynolds Averaged Numerical Simulations (URANS) are also applied, employing the Shear Stress Transport model as the turbulence model. Turbulence-chemistry interactions are modelled by the Eddy Dissipation Concept (EDC) and the Laminar Flamelet Model (LFM). In EDC, a three-step global reaction mechanism is used. In LFM, limitations of the standard non-premixed approach, based on the mixture fraction and the scalar dissipation rate, for lifted flames like the present one, is overcome by adding the progress variable as an additional dimension to the flamelet libraries. URANS is applied only with combination with LFM. LES is applied in combination with EDC and LFM. Special attention is paid to obtaining an adequate grid resolution. Predictions are compared with measurements. It is observed that LES provides a better accuracy compared to URANS, whereas the latter may still be seen useful, since its computational time is shorter. For LES, it is observed that EDC provides a similar, or even slightly better overall-accuracy compared to LFM. On the other hand, it is observed that LFM requires substantially shorter computational times compared to EDC. This makes LFM attractive especially for LES of real combustors requiring much larger grids and/or for cases where a detailed reaction mechanism is of interest.

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