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Stabilization and liftoff length of a non-premixed methane/air jet flame discharging into a high-temperature environment: An accelerated transported PDF method

Jangi, Mehdi LU ; Zhao, Xinyu; Haworth, Dan C. and Bai, Xue-Song LU (2015) In Combustion and Flame 162(2). p.408-419
Abstract
A particle-based transported probability density function (PDF) method with a novel chemistry acceleration technique is developed in this work. The technique is based on the chemistry coordinate mapping (CCM) approach that was proposed in our previous works for accelerating direct numerical simulations (DNS) of partially premixed combustion. The method is first validated using Sandia flames D and F. It is shown that PDF-CCM results converge toward those obtained without CCM as phase-space resolution increases. PDF-CCM is then applied to simulate methane/air lifted jet flames in vitiated coflow reported in experiments by Cabra et al. (2005). It is shown that combustion is initiated in the form of auto-ignition in very fuel-lean gases where... (More)
A particle-based transported probability density function (PDF) method with a novel chemistry acceleration technique is developed in this work. The technique is based on the chemistry coordinate mapping (CCM) approach that was proposed in our previous works for accelerating direct numerical simulations (DNS) of partially premixed combustion. The method is first validated using Sandia flames D and F. It is shown that PDF-CCM results converge toward those obtained without CCM as phase-space resolution increases. PDF-CCM is then applied to simulate methane/air lifted jet flames in vitiated coflow reported in experiments by Cabra et al. (2005). It is shown that combustion is initiated in the form of auto-ignition in very fuel-lean gases where the gas velocity is low (the residence time is long) and the gas temperature is high (the ignition delay time is short). The ignition delay of the mixture below the liftoff position scales well with the liftoff height at different coflow temperature conditions. The combustion process above the liftoff height can develop into different modes depending on the coflow temperature. For high-temperature coflow, a premixed-burned combustion is formed above the liftoff height, which involves fuel-lean to fuel-rich burning modes; a triple-flame structure eventually is formed a few nozzle diameters above the liftoff position. For low-temperature coflow, the ignition delay and the liftoff height are sufficiently large to allow premixing between fuel and oxidizer before the onset of high-temperature combustion; in this case, a lean-to-stoichiometric premixed burn combustion is established downstream of the liftoff height, and no obvious triple-flame structure is formed at this condition. (C) 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
CCM, Transported PDF, Acceleration technique, Lifted flame
in
Combustion and Flame
volume
162
issue
2
pages
408 - 419
publisher
Elsevier
external identifiers
  • wos:000348411900010
  • scopus:84919909191
ISSN
0010-2180
DOI
10.1016/j.combustflame.2014.07.031
language
English
LU publication?
yes
id
0aa9565a-86dd-4b6c-846e-da5f5f46aa9a (old id 5201195)
date added to LUP
2015-03-26 14:16:57
date last changed
2017-09-03 03:59:18
@article{0aa9565a-86dd-4b6c-846e-da5f5f46aa9a,
  abstract     = {A particle-based transported probability density function (PDF) method with a novel chemistry acceleration technique is developed in this work. The technique is based on the chemistry coordinate mapping (CCM) approach that was proposed in our previous works for accelerating direct numerical simulations (DNS) of partially premixed combustion. The method is first validated using Sandia flames D and F. It is shown that PDF-CCM results converge toward those obtained without CCM as phase-space resolution increases. PDF-CCM is then applied to simulate methane/air lifted jet flames in vitiated coflow reported in experiments by Cabra et al. (2005). It is shown that combustion is initiated in the form of auto-ignition in very fuel-lean gases where the gas velocity is low (the residence time is long) and the gas temperature is high (the ignition delay time is short). The ignition delay of the mixture below the liftoff position scales well with the liftoff height at different coflow temperature conditions. The combustion process above the liftoff height can develop into different modes depending on the coflow temperature. For high-temperature coflow, a premixed-burned combustion is formed above the liftoff height, which involves fuel-lean to fuel-rich burning modes; a triple-flame structure eventually is formed a few nozzle diameters above the liftoff position. For low-temperature coflow, the ignition delay and the liftoff height are sufficiently large to allow premixing between fuel and oxidizer before the onset of high-temperature combustion; in this case, a lean-to-stoichiometric premixed burn combustion is established downstream of the liftoff height, and no obvious triple-flame structure is formed at this condition. (C) 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.},
  author       = {Jangi, Mehdi and Zhao, Xinyu and Haworth, Dan C. and Bai, Xue-Song},
  issn         = {0010-2180},
  keyword      = {CCM,Transported PDF,Acceleration technique,Lifted flame},
  language     = {eng},
  number       = {2},
  pages        = {408--419},
  publisher    = {Elsevier},
  series       = {Combustion and Flame},
  title        = {Stabilization and liftoff length of a non-premixed methane/air jet flame discharging into a high-temperature environment: An accelerated transported PDF method},
  url          = {http://dx.doi.org/10.1016/j.combustflame.2014.07.031},
  volume       = {162},
  year         = {2015},
}