Optical Investigation on the Combustion Process Differences between Double-Pilot and Closely-Coupled Triple-Pilot Injection Strategies in a LD Diesel Engine

Michael Denny, Alexios Matamis, Zhenkan Wang, Håkan Persson, Per Tunestal, Mattias Richter, A. Ivind Andersson

Research output: Chapter in Book/Report/Conference proceedingPaper in conference proceedingpeer-review

Abstract

The combustion processes of three injection strategies in a light-duty (LD) diesel engine at a medium load point are captured with a high speed video camera. A double-pilot/main/single-post injection strategy representative of a LD Euro 6 calibration is considered as the reference. There is a modest temporal spacing (dwell) after the first pilot (P1) and second pilot (P2). A second strategy, "A," adds a third pilot (P3). The dwell after both P2 and P3 are several times shorter than in the reference strategy. A third strategy, "B," further reduces all dwells. Each injection has its own associated local peak in the heat release rate (HRR) following some ignition delay. Between these peaks lie local minima, or dips. In all three cases, the fuel from P1 combusts as a propagating premixed flame. For all strategies, the ignition of P2 primarily occurs at its interface with the existing combustion regions. Extinguishing of the prevailing combustion by the fuel jets of later injections is noted in all strategies. This phenomenon is confirmed by comparing the timing of each fuel injection with the dips in the HRR and spatial luminescence over time. These dips after each injection are larger than would be expected by the cooling effect of the injected fuel alone. Furthermore, not all dips in the HRR are the result of this extinguishing, and it would not have been possible to determine if the dips are due to this extinguishing or a simple exhaustion of available fuel without this optical investigation. Even if the precise hydraulic injection timing can be known, knowledge of the spatial relationship of the injected fuel and prevailing combustion is necessary.

Original languageEnglish
Title of host publication International Powertrains, Fuels & Lubricants Meeting
Volume2019-January
DOIs
Publication statusPublished - 2019 Jan 15
EventSAE 2019 International Powertrains, Fuels and Lubricants Meeting, FFL 2019 - San Antonio, United States
Duration: 2019 Jan 222019 Jan 24

Publication series

NameSAE Technical Papers
PublisherSociety of Automotive Engineers
ISSN (Print)0148-7191

Conference

ConferenceSAE 2019 International Powertrains, Fuels and Lubricants Meeting, FFL 2019
Country/TerritoryUnited States
CitySan Antonio
Period2019/01/222019/01/24

Subject classification (UKÄ)

  • Vehicle Engineering
  • Energy Engineering

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