Unravelling the chemical and transport characteristics of turbulent MILD combustion

Developing modern combustion engines needs to address stringent environmental regulations such as efficiency, pollutants and noise. As a promising approach to achieve high efficiency and reduced emissions, moderate or intense low-oxygen dilution (MILD) combustion [1] has been investigated. In MILD conditions, a reactant mixture is preheated and highly diluted by using exhaust gas or flue gas to achieve stable combustion and relatively low flame
temperature. This leads to lower thermal NOx formation and noise, as well as high combustion efficiency. Previous studies addressed key issues for MILD combustion, such as dominant reaction pathways depending on different diluent gases at varying dilution levels, and the morphology of MILD reaction zones exhibiting multimode combustion [2]. However, proper characterization of the structure of turbulent flames at MILD conditions may require a significantly different approach compared to conventional flames depending on the thermochemical conditions of the reactant mixture.