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The 4th Workshop of the Engine Combustion Network (ECN) was held September 5-6, 2015 in Kyoto, Japan. This manuscript presents a summary of the progress in experiments and modeling among ECN contributors leading to a better understanding of soot formation under the ECN “Spray A” configuration and some parametric variants. Relevant published and unpublished work from prior ECN workshops is reviewed. Experiments measuring soot particle size and morphology, soot volume fraction (fv), and transient soot mass have been conducted at various international institutions providing target data for improvements to computational models. Multiple modeling contributions using both the Reynolds Averaged Navier-Stokes (RANS) Equations approach and the Large-Eddy Simulation (LES) approach have been submitted. Among these, various chemical mechanisms, soot models, and turbulence-chemistry interaction (TCI) methodologies have been considered.

Multi-hole diesel fuel injectors have shown significant transients in spreading angle during injections, different than past fundamental research using single-hole injectors. We investigated the effect of a this transient spreading angle on combustion parameters such as ignition delay and lift-off length by comparing a three-hole nozzle (Spray B) and single-hole nozzle (Spray A) with holes of the same size and shape as targets for the Engine Combustion Network (ECN). With the temperature distribution for a target plume of Spray B characterized extensively in a constant-volume combustion chamber, the ignition delay and lift-off length were measured and compared. Results show that the lift-off length of Spray B increases and grows by approximately 1.5 mm after the initial stages of ignition, in an opposite trend compared to Spray A where the lift-off length decreases with time.

This work investigates the injection processes of an eight-hole direct-injection gasoline injector from the Engine Combustion Network (ECN) effort on gasoline sprays (Spray G). Experiments are performed at identical operating conditions by multiple institutions using standardized procedures to provide high-quality target datasets for CFD spray modeling improvement. The initial conditions set by the ECN gasoline spray community (Spray G: Ambient temperature: 573 K, ambient density: 3.5 kg/m3 (∼6 bar), fuel: iso-octane, and injection pressure: 200 bar) are examined along with additional conditions to extend the dataset covering a broader operating range. Two institutes evaluated the liquid and vapor penetration characteristics of a particular 8-hole, 80° full-angle, Spray G injector (injector #28) using Mie scattering (liquid) and schlieren (vapor).