Physical Insights into the Flameless Combustion of Methane under MILD combustion conditions

Moderate or intense low-oxygen dilution (MILD) combustion is a promising technology for energy efficient industrial combustors. Many experimental studies have been carried out on the parameters that characterize the dynamics of this type of combustion, which is associated with intense preheating and dilution. Yet, there is limited understanding about the physical processes that characterize this mode of combustion, which makes it difficult to maintain and to model MILD combustion at different operating conditions. To this end, the mathematical tools provided by the computational singular perturbation (CSP) method can be applied to systematically analyze the relevant physics, by identifying the important dynamical characteristics driven by the key processes. In the current work, CSP tools are used to analyze the dynamics of an EGR-type methane/air premixed flame under MILD combustion conditions that was previously generated in the context of DNS and compare it with a conventional turbulent methane flame. In addition, the topological characteristics of these two flames are identified and compared.