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.
Preview |
Text
Luo 2019 CNF Engine Manuscript.pdf - Accepted Version Download (2MB) | Preview |
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.
| Type: | Article |
|---|---|
| Title: | Flame–spray interaction and combustion features in split-injection spray flames under diesel engine-like conditions |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.combustflame.2019.08.031 |
| Publisher version: | https://doi.org/10.1016/j.combustflame.2019.08.031 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Split-injection, Ignition, Flame–spray interaction, Flame structure, CEMA |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10085629 |
Loading...
Loading...Loading...Loading...Archive Staff Only
 |
View Item |
