Sammendrag
This article presents results of investigation of the
Eddy Dissipation Concept (EDC) in the regime of
Moderate and Intense Low-oxygen Dilution (MILD)
combustion. In the past years extensive numerical and
experimental investigations have been carried out on
MILD combustion. Due to the special MILD features,
where chemical and turbulence time scales are comparable and the Damkohler number is close to the unity, ¨
conditions are far from the flamelet regime. Therefore, numerical studies were mainly focused on the
two turbulence-chemistry interaction models: EDC
and Transported PDF. Both approaches have ability
to incorporate detailed chemical kinetics, though the
latter one is associated with a higher computational
cost. The first one, however, was reported to overpredict the maximum temperature and was a subject of
several modifications in case of MILD regime. Most
of the proposed approaches concern changes in turbulence cascade model constants, what indeed improves
the results but rises question to the generality of this
approach. On the other hand changed constants may
not be consistent with the experiments they were originally derived on. In the present work different modelling approaches of EDC with standard and modified
constants are investigated and the importance of each
effect is outlined. We focused on the description of
the fine structure reactor model and we discussed the
use of different reactor models and their inflow conditions that seem to play a significant role. The calculations were carried out with the use of Ansys Fluent
(AF) and open source software OpenFOAM (OF). The
main test case was the Delft-Jet-in-Hot-Coflow burner
emulating MILD regime.
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