Browse Publications Technical Papers 2019-01-0022
2019-01-15

Optical Investigation on the Combustion Process Differences between Double-Pilot and Closely-Coupled Triple-Pilot Injection Strategies in a LD Diesel Engine 2019-01-0022

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.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Members save up to 18% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:
TECHNICAL PAPER

Effect of Nozzle hole Geometry on a HSDI Diesel Engine-Out Emissions

2003-01-0704

View Details

TECHNICAL PAPER

One-dimensional Simulation Study on the Rule of Several-parameter Matching for the Performance of a Turbocharged Diesel Engine

2008-01-1696

View Details

JOURNAL ARTICLE

The Influence of Injection Strategy and Glow Plug Temperature on Cycle by Cycle Stability Under Cold Idling Conditions for a Low Compression Ratio, HPCR Diesel Engine

2012-01-1071

View Details

X