Chemical analysis of emission characteristics in bluff body stabilized turbulent premixed methane-air flames*

The practical operation of gas turbine combustors typically involves a balance between emissions and flame stability. Operating in the lean regime to maximize efficiency comes at the cost of potential blow-off, which can be prevented by employing flameholding devices like bluff-bodies. The flame dynamics and mixing processes in these combustors depend heavily on the flame chemistry and its interaction with the turbulent processes. Modeling the chemistry is therefore paramount in being able to accurately make predictions regarding the operation of these combustors. Most of the work in this space has been focused on studying unconfined flames. In this study, we perform a chemical kinetic analysis of methane-air flames in a confined bluff-body stabilized combustor at similar conditions as Pathania et al (2017). We use OpenFOAM to perform Large Eddy Simulations and compare the reduced 17-species model by Sankaran (2007) and the detailed GRI 3.0 models in their ability to predict CO emissions. We perform simulations over a computational domain of 4.5 million grid points and compare various chemical and flowfield quantities in the upstream, recirculation, and downstream regions to understand their relative strengths and weaknesses.