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Direct numerical simulation of H2/air combustion with composition stratification in a constant volume enclosure relevant to HCCI engines

Zhang, F. LU ; Liu, H. F. LU ; Yu, R. LU ; Yao, M. and Bai, X. S. LU (2016) In International Journal of Hydrogen Energy 41(31). p.13758-13770
Abstract

Two-dimensional direct numerical simulation (2-D DNS) is used to investigate the effect of turbulence intensity and composition stratification on H2/air mixture auto-ignition in a constant volume enclosure relevant to homogeneous charge compression ignition (HCCI) engines. Different turbulence levels, composition fluctuations, EGR (Exhaust Gas Recirculation) ratios, initial pressure, domain lengths and energy spectra are simulated with detailed analysis in ten 2-D DNS cases. The results show that the ignition delay time tends to be prolonged and the heat release rate increased under higher turbulence intensity. Turbulence can affect the reaction zone, e.g., through wrinkling of reaction front and enhancement of mixing and... (More)

Two-dimensional direct numerical simulation (2-D DNS) is used to investigate the effect of turbulence intensity and composition stratification on H2/air mixture auto-ignition in a constant volume enclosure relevant to homogeneous charge compression ignition (HCCI) engines. Different turbulence levels, composition fluctuations, EGR (Exhaust Gas Recirculation) ratios, initial pressure, domain lengths and energy spectra are simulated with detailed analysis in ten 2-D DNS cases. The results show that the ignition delay time tends to be prolonged and the heat release rate increased under higher turbulence intensity. Turbulence can affect the reaction zone, e.g., through wrinkling of reaction front and enhancement of mixing and heat transfer. Higher composition stratification can smoothen the overall heat release rate and shorten the ignition delay time. Budgets terms and Probability Density Function (PDF) of density weighted displacement speed show that in HCCI engines flame propagation can co-exist with volumetric auto-ignition. As expected, lower pressure leads to thicker flame thickness and longer ignition delay time. Increasing EGR ratio has a negative influence on the formation of OH reaction, resulting in a longer ignition delay time. Two energy spectra with respect to low and high Reynolds number are compared to show a discrepancy on ignition delay time due to different kinetic energy dissipation rates.

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Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
2-D DNS, EGR, Energy spectrum, HCCI engines, Stratified mixture, Turbulent combustion
in
International Journal of Hydrogen Energy
volume
41
issue
31
pages
13 pages
publisher
Elsevier
external identifiers
  • scopus:84991396144
  • wos:000381533500045
ISSN
0360-3199
DOI
10.1016/j.ijhydene.2016.06.192
language
English
LU publication?
yes
id
628da4fb-7c7f-40a6-9516-03708b1da1c7
date added to LUP
2016-12-19 14:11:37
date last changed
2017-10-08 04:56:18
@article{628da4fb-7c7f-40a6-9516-03708b1da1c7,
  abstract     = {<p>Two-dimensional direct numerical simulation (2-D DNS) is used to investigate the effect of turbulence intensity and composition stratification on H<sub>2</sub>/air mixture auto-ignition in a constant volume enclosure relevant to homogeneous charge compression ignition (HCCI) engines. Different turbulence levels, composition fluctuations, EGR (Exhaust Gas Recirculation) ratios, initial pressure, domain lengths and energy spectra are simulated with detailed analysis in ten 2-D DNS cases. The results show that the ignition delay time tends to be prolonged and the heat release rate increased under higher turbulence intensity. Turbulence can affect the reaction zone, e.g., through wrinkling of reaction front and enhancement of mixing and heat transfer. Higher composition stratification can smoothen the overall heat release rate and shorten the ignition delay time. Budgets terms and Probability Density Function (PDF) of density weighted displacement speed show that in HCCI engines flame propagation can co-exist with volumetric auto-ignition. As expected, lower pressure leads to thicker flame thickness and longer ignition delay time. Increasing EGR ratio has a negative influence on the formation of OH reaction, resulting in a longer ignition delay time. Two energy spectra with respect to low and high Reynolds number are compared to show a discrepancy on ignition delay time due to different kinetic energy dissipation rates.</p>},
  author       = {Zhang, F. and Liu, H. F. and Yu, R. and Yao, M. and Bai, X. S.},
  issn         = {0360-3199},
  keyword      = {2-D DNS,EGR,Energy spectrum,HCCI engines,Stratified mixture,Turbulent combustion},
  language     = {eng},
  month        = {08},
  number       = {31},
  pages        = {13758--13770},
  publisher    = {Elsevier},
  series       = {International Journal of Hydrogen Energy},
  title        = {Direct numerical simulation of H<sub>2</sub>/air combustion with composition stratification in a constant volume enclosure relevant to HCCI engines},
  url          = {http://dx.doi.org/10.1016/j.ijhydene.2016.06.192},
  volume       = {41},
  year         = {2016},
}