Modelling of diesel spray flames under engine-like conditions using an accelerated Eulerian Stochastic Field method
(2018) In Combustion and Flame 193. p.363-383- Abstract
This paper aims to simulate diesel spray flames across a wide range of engine-like conditions using the Eulerian Stochastic Field probability density function (ESF-PDF) model. The ESF model is coupled with the Chemistry Coordinate Mapping approach to expedite the calculation. A convergence study is carried out for a number of stochastic fields at five different conditions, covering both conventional diesel combustion and low-temperature combustion regimes. Ignition delay time, flame lift-off length as well as distributions of temperature and various combustion products are used to evaluate the performance of the model. The peak values of these properties generated using thirty-two stochastic fields are found to converge, with a maximum... (More)
This paper aims to simulate diesel spray flames across a wide range of engine-like conditions using the Eulerian Stochastic Field probability density function (ESF-PDF) model. The ESF model is coupled with the Chemistry Coordinate Mapping approach to expedite the calculation. A convergence study is carried out for a number of stochastic fields at five different conditions, covering both conventional diesel combustion and low-temperature combustion regimes. Ignition delay time, flame lift-off length as well as distributions of temperature and various combustion products are used to evaluate the performance of the model. The peak values of these properties generated using thirty-two stochastic fields are found to converge, with a maximum relative difference of 27% as compared to those from a greater number of stochastic fields. The ESF-PDF model with thirty-two stochastic fields performs reasonably well in reproducing the experimental flame development, ignition delay times and lift-off lengths. The ESF-PDF model also predicts a broader hydroxyl radical distribution which resembles the experimental observation, indicating that the turbulence–chemistry interaction is captured by the ESF-PDF model. The validated model is subsequently used to investigate the flame structures under different conditions. Analyses based on flame index and formaldehyde distribution suggest that a triple flame, which consists of a rich premixed flame, a diffusion flame and a lean premixed flame, is established in the earlier stage of the combustion. As the combustion progresses, the lean premixed flame weakens and diminishes with time. Eventually, only a double-flame structure, made up of the diffusion flame and the rich premixed flame, is observed. The analyses for various ambient temperatures show that the triple-flame structure remains for a longer period of time in cases with lower ambient temperatures. The present study shows that the ESF-PDF method is a valuable alternative to Lagrangian particle PDF methods.
(Less)
- author
- Pang, Kar Mun ; Jangi, Mehdi LU ; Bai, Xue Song LU ; Schramm, Jesper and Walther, Jens Honore
- organization
- publishing date
- 2018-07-01
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Diesel engine, Eulerian Stochastic Field, Probability density function, Spray flame, Turbulent combustion
- in
- Combustion and Flame
- volume
- 193
- pages
- 21 pages
- publisher
- Elsevier
- external identifiers
-
- scopus:85045547630
- ISSN
- 0010-2180
- DOI
- 10.1016/j.combustflame.2018.03.030
- language
- English
- LU publication?
- yes
- id
- 5085f46e-9cfd-4cf5-8fda-12c106b0939f
- date added to LUP
- 2018-04-26 08:30:37
- date last changed
- 2022-04-25 07:09:17
@article{5085f46e-9cfd-4cf5-8fda-12c106b0939f,
abstract = {{<p>This paper aims to simulate diesel spray flames across a wide range of engine-like conditions using the Eulerian Stochastic Field probability density function (ESF-PDF) model. The ESF model is coupled with the Chemistry Coordinate Mapping approach to expedite the calculation. A convergence study is carried out for a number of stochastic fields at five different conditions, covering both conventional diesel combustion and low-temperature combustion regimes. Ignition delay time, flame lift-off length as well as distributions of temperature and various combustion products are used to evaluate the performance of the model. The peak values of these properties generated using thirty-two stochastic fields are found to converge, with a maximum relative difference of 27% as compared to those from a greater number of stochastic fields. The ESF-PDF model with thirty-two stochastic fields performs reasonably well in reproducing the experimental flame development, ignition delay times and lift-off lengths. The ESF-PDF model also predicts a broader hydroxyl radical distribution which resembles the experimental observation, indicating that the turbulence–chemistry interaction is captured by the ESF-PDF model. The validated model is subsequently used to investigate the flame structures under different conditions. Analyses based on flame index and formaldehyde distribution suggest that a triple flame, which consists of a rich premixed flame, a diffusion flame and a lean premixed flame, is established in the earlier stage of the combustion. As the combustion progresses, the lean premixed flame weakens and diminishes with time. Eventually, only a double-flame structure, made up of the diffusion flame and the rich premixed flame, is observed. The analyses for various ambient temperatures show that the triple-flame structure remains for a longer period of time in cases with lower ambient temperatures. The present study shows that the ESF-PDF method is a valuable alternative to Lagrangian particle PDF methods.</p>}},
author = {{Pang, Kar Mun and Jangi, Mehdi and Bai, Xue Song and Schramm, Jesper and Walther, Jens Honore}},
issn = {{0010-2180}},
keywords = {{Diesel engine; Eulerian Stochastic Field; Probability density function; Spray flame; Turbulent combustion}},
language = {{eng}},
month = {{07}},
pages = {{363--383}},
publisher = {{Elsevier}},
series = {{Combustion and Flame}},
title = {{Modelling of diesel spray flames under engine-like conditions using an accelerated Eulerian Stochastic Field method}},
url = {{http://dx.doi.org/10.1016/j.combustflame.2018.03.030}},
doi = {{10.1016/j.combustflame.2018.03.030}},
volume = {{193}},
year = {{2018}},
}