Session: 03-03 Advanced Compression Ignition Combustion Strategies

Paper Number: 197375

197375 - The Impact of H2 Direct-Injector Configuration on Mixture Formation and Combustion in Heavy-Duty Optical Engine 

Abstract: 

The mixture distribution established at the time of ignition is a critical factor that governs the subsequent flame evolution and NOx formation in direct-injected lean-burn hydrogen engines. H2 direct-injectors commonly feature outward-opening pintle design and their outflow boundary can be modified by use of attachments that redirect the flow. We used four injector designs with different outflow properties in a heavy-duty optical engine to understand which injector properties support optimal mixture formation with fast combustion propagation. These designs included a baseline hollow-cone flow pattern, an injector with a clover-leaf shaped outflow pattern which prevents the jet collapse, a single-hole injector cap to redirect the flow into a tumbling motion, and a 5-hole wide-cone injector cap which also avoid the jet collapse. For every injector configuration, the SOI time has been varied from -340°CA to -90° after top dead center, and the injection pressure was varied between 20 bar and 40 bar. Tracer-PLIF and high-speed OH* chemiluminescence were used to characterize in-cylinder mixture distribution and the flame evolution, respectively. The clover-leaf pattern injector delivered overall best performance across varied injector timings. However, different injector designs showed significant sensitivity to injection timing and injection pressure and the optimal operating point was not identical for all injectors. This was attributed to the interaction of fuel jet with combustion chamber geometry at the time of injection and the in-cylinder bulk motion generated by the injection.

Presenting Author: Aleš Srna Sandia National Laboratories

Presenting Author Biography: Dr. Aleš Srna is Principal Member of Technical Staff at Sandia National Laboratories (SNL), responsible for gaseous fuels combustion research at the Sandia Heavy-Duty Optical Engine laboratory. Tightly collaborating with industry partners, Dr. Srna uses optical and laser-based diagnostics to close the knowledge gaps about in-cylinder processes to improve efficiency and decrease emissions of large on- and off-road engines. Dr. Srna graduated in 2018 from ETH Zurich, Switzerland, and worked as a postdoctoral researcher at UNSW Sydney before joining Sandia in 2020.

Authors:

Taesong Lee Sandia National Laboratories
Vasco O. Duke Universidad Tecnológica de Panamá
Humaid Qasem Sandia National Laboratories
Aleš Srna Sandia National Laboratories