TY - JOUR
T1 - Turbulence-chemistry interactions in a heavy-duty compression-ignition engine
AU - Raj Mohan, V.
AU - Haworth, D. C.
N1 - Publisher Copyright:
© 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
PY - 2015
Y1 - 2015
N2 - The influences of unresolved turbulent fluctuations in composition and temperature (turbulence-chemistry interactions - TCI) on heat release, flame structure, and emissions are explored in unsteady Reynolds-averaged simulations for a heavy-duty diesel engine at four operating conditions. TCI are isolated and quantified by comparing results from a transported probability density function (PDF) method with those from a model that neglects the influence of fluctuations on local mean reaction rates (a well-stirred-reactor - WSR-model), with all other aspects of the modeling being the same (e.g., spray model, gas-phase chemical mechanism, and soot model). The simulations feature standard fuel-spray and turbulence models, skeletal-level gas-phase chemistry, and a semi-empirical two-equation soot model. Computed pressure and heat-release traces, turbulent flame structure, and emissions from the WSR and PDF models show marked differences, with the PDF-model results being in closer agreement with experiment in most cases. The soot results are especially striking. Computed soot levels from the PDF model are within a factor of five of the measured engine-out particulate matter, and computed soot levels from the WSR and PDF models differ by up to several orders of magnitude, with the PDF-model results being in much closer agreement with experiment. The results show that TCI are important in compression-ignition engines, and that accurate accounting for turbulent fluctuations is at least as important as accurate kinetic rate parameters in the gas-phase chemistry and soot models.
AB - The influences of unresolved turbulent fluctuations in composition and temperature (turbulence-chemistry interactions - TCI) on heat release, flame structure, and emissions are explored in unsteady Reynolds-averaged simulations for a heavy-duty diesel engine at four operating conditions. TCI are isolated and quantified by comparing results from a transported probability density function (PDF) method with those from a model that neglects the influence of fluctuations on local mean reaction rates (a well-stirred-reactor - WSR-model), with all other aspects of the modeling being the same (e.g., spray model, gas-phase chemical mechanism, and soot model). The simulations feature standard fuel-spray and turbulence models, skeletal-level gas-phase chemistry, and a semi-empirical two-equation soot model. Computed pressure and heat-release traces, turbulent flame structure, and emissions from the WSR and PDF models show marked differences, with the PDF-model results being in closer agreement with experiment in most cases. The soot results are especially striking. Computed soot levels from the PDF model are within a factor of five of the measured engine-out particulate matter, and computed soot levels from the WSR and PDF models differ by up to several orders of magnitude, with the PDF-model results being in much closer agreement with experiment. The results show that TCI are important in compression-ignition engines, and that accurate accounting for turbulent fluctuations is at least as important as accurate kinetic rate parameters in the gas-phase chemistry and soot models.
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U2 - 10.1016/j.proci.2014.06.098
DO - 10.1016/j.proci.2014.06.098
M3 - Article
AN - SCOPUS:84947899973
SN - 1540-7489
VL - 35
SP - 3053
EP - 3060
JO - Proceedings of the Combustion Institute
JF - Proceedings of the Combustion Institute
IS - 3
ER -