  Distributed combustion, often associated with the low-oxygen condition,
offers ultra-low NOX emission. However, it was recently achieved without
combustion air dilution or internal flue gas recirculation, using a distinct
approach called Mixture Temperature-Controlled combustion. Here, the fuel-air
stream is cooled at the inlet to delay ignition and hence foster homogeneous
mixture formation. The aim of this numerical study aims to understand the
operation of this combustion concept better and present a robust framework for
distributed combustion modeling in a parameter range where such operation was
not predicted before by any existing theory. Further, liquid fuel combustion
was evaluated that brings additional complexity. Four operating conditions were
presented at which distributed combustion was observed. The reacting flow was
modeled by Flamelet-Generated Manifold, based on a detailed n-dodecane
mechanism. The Zimont turbulent flame speed model was used with significantly
reduced coefficients to achieve distributed combustion. The droplets of
airblast atomization were tracked in a Lagrangian frame. The numerical results
were validated by Schlieren images and acoustic spectra. It was concluded that
the reactant dilution ratio remained below 0.25 through the combustion chamber,
revealing that the homogeneous fuel-air mixture is the principal reason for
excellent flame stability and ultra-low NOX emission without significant
internal recirculation. The potential applications of these results are
boilers, furnaces, and gas turbines.
