More and more engine systems are designed with lean premixed turbulent flames, for ecological reasons and pollutant emission restrictions. Unfortunately, these combustion systems are prone to flame instabilities, since the heat release is very sensitive to air-fuel ratio variations for lean mixture. In the present work, three Large Eddy Simulation (LES) combustion models for lean inhomogeneously premixed turbulent combustion are compared, implemented and validated using an unstructured commercial solver against experimental results: Thickenened Flame (TF), Turbulent Flame speed Closure (TFC-LES) and Subgrid Flame Closure (SFC) models. The derivation of the new SFC model is detailed in this thesis. The validation is based on velocity profiles, as well as flame position measurements for three burners: The Volvo test-rig, the Paul Scherrer Institut (PSI) burner, and our TD1 burner. The SFC and TF' models have given similar and accurate results compared to the experimental measurements. The TFC-LES model requires the adaptation of its model constant.
«
More and more engine systems are designed with lean premixed turbulent flames, for ecological reasons and pollutant emission restrictions. Unfortunately, these combustion systems are prone to flame instabilities, since the heat release is very sensitive to air-fuel ratio variations for lean mixture. In the present work, three Large Eddy Simulation (LES) combustion models for lean inhomogeneously premixed turbulent combustion are compared, implemented and validated using an unstructured commerc...
»