Validation of standard and extended Eddy Dissipation Concept Model for the Delft Jet-in Hot Coflow (DJHC) flame

Abstract (2016)

Authors

X. Huang Fluid Mechanics - Mechanical, Maritime and Materials Engineering
D.J.E.M. Roekaerts Fluid Mechanics - Mechanical, Maritime and Materials Engineering
Research Group
Fluid Mechanics (Mechanical, Maritime and Materials Engineering) (TU Delft)
Copyright: © 2016 H. Bao, X. Huang, D.J.E.M. Roekaerts
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Published Date

2016

Language

English

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Faculty

Mechanical, Maritime and Materials Engineering

Department

Process and Energy

Research Group

Fluid Mechanics

Abstract

The Delft
Jet-in Hot Coflow (DJHC) burner is used to investigate flameless combustion by
imitating the recirculation flow characteristics appearing in a real complex
furnace via a hot diluted coflow[1]. A welldefined stream of high temperature,
low oxygen concentration combustion products is injected around the fuel jet as
oxidizer in order to obtain ‘Moderate and Intense Low-oxygen Dilution (MILD)’
combustion conditions. For a range of jet and coflow conditions detailed
experiments were made [2] and also several numerical validation studies, see
e.g. [4,5]. The Eddy Dissipation Concept (EDC) model for turbulence chemistry
interaction modeling has been widely used for modeling MILD combustion. EDC is
providing a closure for the mean chemical source term based on a proposed
microstructure of the reacting flow following from energy cascade concepts. It
assumes that chemical reactions can only happen in the smallest eddies, whose
size are of the same order of magnitude as the Kolmogorov scales, the so-called
fine structures. Thus, the fraction of fine structure 훾훾∗ and mean residence time 휏휏∗ (the reciprocal of it denotes the mass
exchange between reactants inside fine structure and the surrounding) are
necessary for EDC simulation. They are related to turbulent kinetic energy 푘푘 and eddy dissipation rate 휀휀 (which are calculated from turbulent models)
via two constants 퐶퐶퐷퐷1 and 퐶퐶퐷퐷2 . It has been confirmed that 휀휀 = 2퐶퐶퐷퐷1푢푢∗3/퐿퐿∗ = 4퐶퐶퐷퐷2푢푢∗2/3퐿퐿∗2.