Efficient Three Dimensional Time-Domain Combustion Noise Simulation of a Premixed Flame Using Acoustic Perturbation Equations and Incompressible LES
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Numerical studies of pulverized coal swirl combustion in oxy-fuel
atmosphere are carried out. Thereby two issues are especially addressed:
(1) how LES and RANS impact differently the predictions of combustion
properties even though, in both approaches, the same kinetic rates are
used to represent the coal combustion processes; (2) how the numerical
multiphase treatments may affect the prediction of micro-process
interaction as well as the range in which these processes are not
negligible. For that purpose a methodology is developed based on an
Eulerian-Lagrangian oxy-coal combustion module which is designed relying
on the state of the art models as implemented in the commercial code
ANSYS Fluent 17. This especially includes three kinetic rates for the
description of coal combustion, namely coal devolatilization, volatile
combustion and char combustion. Based on an appropriate Stokes number
consideration, a full two-way inter-phase coupling has been numerically
adopted.
To assess the prediction capability of the overall model, a new set of
experimental data from a 60 kW(th) oxy-coal test facility is employed.
First, the model validation is ensured by comparison of results in terms
of flow field and products from volatile and char combustion. Then, an
analysis is performed to elucidate how the two-phase turbulence modeling
impacts the thermal flow predictions along with the evolution of
multiphase oxy-coal combustion properties.
Finally, it is demonstrated how the numerical multiphase treatments
affect the prediction of micro process interaction in terms of coal
devolatilization, coal particle distribution due to turbulent particle
dispersion, and of gaseous heat release as well as char burnout. The
range in which these interphase processes (subgrid scale particle
dispersion) are not negligible is also pointed out in terms of subgrid
scale Stokes number. (C) 2017 Elsevier Ltd. All rights reserved.