Autoignition dynamics of DME/air and EtOH/air homogeneous mixtures

Theory of first-stage ignition delay in hydrocarbon NTC chemistry

The dynamics of homogeneous isochoric explosions of dimethylether (DME)/air and ethanol (EtOH)/air mixtures were studied and compared at relatively low initial temperatures (≤ 700 K) using algorithmic tools derived from the methodology of computational singular perturbation. In the DME case, it is shown that the low-temperature oxidation is dominated by reactions involving heavy carbonaceous species, in contrast to the high-temperature case where oxidation is dominated by reactions involving light carbonaceous species. Moreover, it is demonstrated that the outcome of the competition between two specific reactions is the cause of the exhibited negative temperature coefficient (NTC). In the EtOH case, the analysis points to the importance of carbonaceous species and in particular acetaldehyde, which is different from what happens at elevated initial temperatures (above 1000 K), where hydrogen chemistry dominates the entirety of the oxidation process. The autoignition dynamics of both mixtures are shown to b...

Comparative investigation of homogeneous autoignition of DME/air and EtOH/air mixtures at low initial temperatures

Although impressive advances have been achieved in the area of tabulated chemistry for turbulent combustion modeling, table generation remains a tedious task, sometimes as costly as the computation itself. In this work, we intend to offer an alternative to tabulation, applied to the MIL turbulent combustion model. An explicit expression for chemical times, function of pressure, temperature, and mixture fraction (Boivin et al., 2011), is successfully implemented and used instead of tabulated chemistry in the simulation of a supersonic H2–O2 lifted flame.

Explicit Chemical Timescale as a Substitute for Tabulated Chemistry in a H2–O2 Turbulent Flame Simulation

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Lucrezia Veggi

Papers

Explicit formulation of the reactivity of hydrogen, methane and decane