eprintid: 10085629
rev_number: 25
eprint_status: archive
userid: 608
dir: disk0/10/08/56/29
datestamp: 2019-11-12 15:43:26
lastmod: 2021-10-09 23:11:17
status_changed: 2019-11-12 15:43:26
type: article
metadata_visibility: show
creators_name: Zhao, W
creators_name: Wei, H
creators_name: Jia, M
creators_name: Lu, Z
creators_name: Luo, KH
creators_name: Chen, R
creators_name: Zhou, L
title: Flame–spray interaction and combustion features in split-injection spray flames under diesel engine-like conditions
ispublished: pub
divisions: UCL
divisions: B04
divisions: C05
divisions: F45
keywords: Split-injection, Ignition, Flame–spray interaction, Flame structure, CEMA
note: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
abstract: In compression ignition engines, split-injection strategy has shown great benefits in reducing pollutant emissions and improving combustion efficiency. Spray–flame interaction involving in split injections is significantly complex, which affects the ignition process and even pollutant emissions. Therefore, the objective of this study is to investigate how the flame–spray interaction affects the subsequent ignition process and combustion features in split injections under diesel engine-like conditions. In this work, large eddy simulation coupled with a 54-species mechanism for split injections of n-dodecane is performed to study the effect of injection duration and dwell times (DTs) on spray–flame interactions and the ignition mechanism. The numerical model gives a reasonable agreement with the experiments in terms of the vapor penetration length, ignition delay times, mixture fraction distributions and the flame structures. The present study revealed that combustion for split injections is a multi-stage process and the ignition processes for the first and second injections are controlled by different mechanisms, namely autoignition for the first injection, and the accelerating ignition for the second injection due to the intermediate species and heating effect formed in the first injection. Moreover, the increase in dwell time between individual injections reduces the subsequently promoting ignition effect for the second injection and thus weakens the interacting process between the two injections. Consumption of the fuel in the first injection leads to a temperature increase and production of different species, which in turn accelerates the ignition of the second injection. Finally, the competition between the local flow timescale and chemical timescale is investigated based on the chemical explosive mode analysis (CEMA) methods. A balance between reaction and mixing processes dominates the combustion of the quasi-steady spray in the second injection with a short DT. However, the flame is controlled by autoignition when a longer DT is used.
date: 2019-12
date_type: published
official_url: https://doi.org/10.1016/j.combustflame.2019.08.031
oa_status: green
full_text_type: other
language: eng
primo: open
primo_central: open_green
verified: verified_manual
elements_id: 1693269
doi: 10.1016/j.combustflame.2019.08.031
lyricists_name: Luo, Kai
lyricists_id: KLUOX54
actors_name: Allington-Smith, Dominic
actors_id: DAALL44
actors_role: owner
full_text_status: public
publication: Combustion and Flame
volume: 210
pagerange: 204-221
citation:        Zhao, W;    Wei, H;    Jia, M;    Lu, Z;    Luo, KH;    Chen, R;    Zhou, L;      (2019)    Flame–spray interaction and combustion features in split-injection spray flames under diesel engine-like conditions.                   Combustion and Flame , 210    pp. 204-221.    10.1016/j.combustflame.2019.08.031 <https://doi.org/10.1016/j.combustflame.2019.08.031>.       Green open access   
 
document_url: https://discovery.ucl.ac.uk/id/eprint/10085629/7/Luo%202019%20CNF%20Engine%20Manuscript.pdf