CFD Evaluation of Soot Formation in a Gas Turbine Combustor Using a Flamelet Progress Variable Approach

An overview is provided of a CFD evaluation of soot formation in a rich bum - quick mix - lean bum (RQL)-type gasturbine model combustor flowing ethylene and air at near-stoichiometric conditions. The Open National Combustion Code (OpenNCC) was used to perform reacting flow computations with a newly formulated Multiple Time-Scale (MTS) Flamelet Progress Variable (FPV) approach for the DLR’s experimental combustor. The MTS approach helped accelerate the convergence of soot quantities of interest by solving them as secondary progress variables, in addition to solving for the primary progress variable solution in the FPV approach. Flow and flame characteristics, along with soot mass-fraction and soot-number density were predicted using a 75 species chemical kinetics model. The CFD analysis predicted very similar flow characteristics and qualitatively similar soot mass fractions when compared with the experimental data. The OpenNCC CFD analysis using the new MTS-FPV approach and a two-equation soot-model helps establish the framework to evaluate more detailed soot-modeling approaches in future computational studies.