Ultra-lean combustion mode

Recent achievements in development of ultra-lean combustion technology and important historical milestones concerning excess-enthalpy burning (i.e., superadiabatic combustion) of near-limit mixtures are summarized within this chapter. Fundamental knowledge and practical findings obtained through relevant experimental and computational studies are reviewed. Scientific progress in studying ultra-lean (i) hydrogen, (ii) methane, and (iii) dimethyl ether flames is highlighted in the given context. Specific issues concerning combustion chemistry and physics as well as interactions of various phenomena involved within these systems are particularly discussed.