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Title: Characterisation of two-stage ignition in diesel engine-relevant thermochemical conditions using direct numerical simulation

Abstract

With the goal of providing a more detailed fundamental understanding of ignition processes in diesel engines, this study reports analysis of a direct numerical simulation (DNS) database. In the DNS, a pseudo turbulent mixing layer of dimethyl ether (DME) at 400 K and air at 900 K is simulated at a pressure of 40 atmospheres. At these conditions, DME exhibits a two-stage ignition and resides within the negative temperature coefficient (NTC) regime of ignition delay times, similar to diesel fuel. The analysis reveals a complex ignition process with several novel features. Autoignition occurs as a distributed, two-stage event. The high-temperature stage of ignition establishes edge flames that have a hybrid premixed/autoignition flame structure similar to that previously observed for lifted laminar flames at similar thermochemical conditions. In conclusion, a combustion mode analysis based on key radical species illustrates the multi-stage and multi-mode nature of the ignition process and highlights the substantial modelling challenge presented by diesel combustion.

Authors:
ORCiD logo [1];  [2];  [3];  [4];  [4]
  1. Sandia National Lab. (SNL-CA), Livermore, CA (United States); The Univ. of New South Wales, Sydney, NSW (Australia)
  2. The Univ. of New South Wales, Sydney, NSW (Australia)
  3. The Univ. of Melbourne, Melbourne, VIC (Australia)
  4. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sandia National Laboratories, Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1326054
Alternate Identifier(s):
OSTI ID: 1358971
Report Number(s):
SAND-2016-5708J
Journal ID: ISSN 0010-2180; 643523
Grant/Contract Number:
AC04-94AL85000; SC0001198
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Combustion and Flame
Additional Journal Information:
Journal Volume: 172; Journal Issue: C; Journal ID: ISSN 0010-2180
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
97 MATHEMATICS AND COMPUTING; 33 ADVANCED PROPULSION SYSTEMS; diesel-relevant; autoignition; edge flame; cool flame; negative temperature coefficient; direct numerical simulation

Citation Formats

Krisman, Alex, Hawkes, Evatt R., Talei, Mohsen, Bhagatwala, Ankit, and Chen, Jacqueline H. Characterisation of two-stage ignition in diesel engine-relevant thermochemical conditions using direct numerical simulation. United States: N. p., 2016. Web. doi:10.1016/j.combustflame.2016.06.010.
Krisman, Alex, Hawkes, Evatt R., Talei, Mohsen, Bhagatwala, Ankit, & Chen, Jacqueline H. Characterisation of two-stage ignition in diesel engine-relevant thermochemical conditions using direct numerical simulation. United States. doi:10.1016/j.combustflame.2016.06.010.
Krisman, Alex, Hawkes, Evatt R., Talei, Mohsen, Bhagatwala, Ankit, and Chen, Jacqueline H. Tue . "Characterisation of two-stage ignition in diesel engine-relevant thermochemical conditions using direct numerical simulation". United States. doi:10.1016/j.combustflame.2016.06.010. https://www.osti.gov/servlets/purl/1326054.
@article{osti_1326054,
title = {Characterisation of two-stage ignition in diesel engine-relevant thermochemical conditions using direct numerical simulation},
author = {Krisman, Alex and Hawkes, Evatt R. and Talei, Mohsen and Bhagatwala, Ankit and Chen, Jacqueline H.},
abstractNote = {With the goal of providing a more detailed fundamental understanding of ignition processes in diesel engines, this study reports analysis of a direct numerical simulation (DNS) database. In the DNS, a pseudo turbulent mixing layer of dimethyl ether (DME) at 400 K and air at 900 K is simulated at a pressure of 40 atmospheres. At these conditions, DME exhibits a two-stage ignition and resides within the negative temperature coefficient (NTC) regime of ignition delay times, similar to diesel fuel. The analysis reveals a complex ignition process with several novel features. Autoignition occurs as a distributed, two-stage event. The high-temperature stage of ignition establishes edge flames that have a hybrid premixed/autoignition flame structure similar to that previously observed for lifted laminar flames at similar thermochemical conditions. In conclusion, a combustion mode analysis based on key radical species illustrates the multi-stage and multi-mode nature of the ignition process and highlights the substantial modelling challenge presented by diesel combustion.},
doi = {10.1016/j.combustflame.2016.06.010},
journal = {Combustion and Flame},
number = C,
volume = 172,
place = {United States},
year = {Tue Aug 30 00:00:00 EDT 2016},
month = {Tue Aug 30 00:00:00 EDT 2016}
}

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