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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).

This paper presents results of a coupling of the Volume-of-Fluid Large-Eddy simulation (VOF-LES) of the jet primary breakup with a Lagrangian stochastic spray simulation of a GDi multi-hole injector. The objective is to assess the potential of replacing the phenomenological models of jet primary atomization with the stochastic parcel size - velocity data extracted from the VOF-LES analysis. The paper describes the methodology and assesses the predictive capability achieved, through comparison of the Lagrangian far-field spray simulation results with the complete experimental spray characterization data under the atmospheric ambient conditions. The injector sac-nozzle flow and jet primary breakup simulation is performed with the Open-FOAM code. The simulation of the spray development processes - of propagation, evaporation and secondary atomization - is performed with the AVL-FIRE commercial CFD code adopting the standard Lagrangian discrete droplet method.

With increasingly stringent emissions regulations and concurrent requirements for enhanced engine thermal efficiency, a comprehensive characterization of the automotive gasoline fuel spray has become essential. The acquisition of accurate and repeatable spray data is even more critical when a combustion strategy such as gasoline direct injection is to be utilized. Without industry-wide standardization of testing procedures, large variablilities have been experienced in attempts to verify the claimed spray performance values for the Sauter mean diameter, Dv90, tip penetration and cone angle of many types of fuel sprays. A new SAE Recommended Practice document, J2715, has been developed by the SAE Gasoline Fuel Injection Standards Committee (GFISC) and is now available for the measurement and characterization of the fuel sprays from both gasoline direct injection and port fuel injection injectors.

A novel measurement technique to evaluate the transient nature of the pulsing sprays from gasoline fuel injectors is created by combining and synchronizing established laser diffraction and high-speed imaging measurements. Both laser diffraction measurements and high-speed images are synchronized, enabling a maximum of two thousand measurements per second to be acquired. By combining the time-resolved drop size measurements with the synchronized spray images, the transient nature of the spray characteristics in relation to injector logic signal timing, injection frequency, and measurement location can be revealed. In addition, the drop size and optical concentration (or obscuration) trends of the spray can be correlated. This paper presents experimental results using this technique on a production dual spray port fuel injector spray.

This paper presents an imaging-based diagnostic technique to quantify the pulse-to-pulse variability of macroscopic fuel spray characteristics for Direct-Injection Spark-Ignition (DISI) engine applications. The analysis approach is based on the construction of a spray ensemble image, reflecting the regions of probability of liquid presence for a set of images. Overlaying of an individual spray boundary on the probability-based ensemble image can further enhance the two-dimensional visualization of the pulse-to-pulse spray variations. Spray structures at three experimental conditions were examined: room ambient, and early and late injection conditions inside an optical engine. While the spray structure was observed to be considerably different for the three conditions, the magnitudes of variation of global spray shape and spray tip penetration distance were found to be of similar order.