Project Details
Projekt
Experimental investigation of the influence of mixture preparation on cyclic variations in direct-injection hydrogen-fueled spark ignition engines
Applicant
Professor Dr. Sebastian Kaiser
Subject Area
Energy Process Engineering
Term
since 2019
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 349537577
In the second funding period of Research Unit FOR 2687, sub-project 3 experimentally investigates cyclic variations in hydrogen-fueled spark-ignition engines. In particular, we examine that part of the cause-and-effect chain that leads from the direct injection of the fuel into the cylinder to the variations in the early flame propagation. Cyclic variations are chaotic variations in the thermodynamic metrics of each engine cycle, like peak pressure, fuel burn rate and indicated mean effective pressure. They are associated with phenomena like knock and misfires that fundamentally limit the engine efficiency. Compared to hydrocarbons, hydrogen has very different properties that strongly influence the fuel/air mixing and combustion. Very little is known about cyclic variability with this fuel, hindering hydrogen engine development. The goal of this sub-project is to gain a detailed understanding and from that a conceptual model of the part of the cause-and-effect chain leading from direct injection and mixing via ignition and inflammation to the resulting cyclic variations. Here, this is achieved by experiments in collaboration with simulations, the latter in other sub-projects of FOR 2687. Therefore, a further goal is providing suitable experimental data for the validation of these simulation methods, and conversely analyses of the simulation results for a more complete assessment and understanding of the experiments. In terms of methods, we aim to develop the optical imaging techniques that are currently insufficient for high-quality measurements with hydrogen as a fuel. Also, methods for the analysis of spatio-temporally partially coherent complex flows are to be developed be able to back-track from the effect to the causes of cyclic variability. The experiments are performed in an optically accessible single-cylinder research engine. We use optical imaging at high frame rates (10 000 to 100 000 frames per second). The hydrogen injection is visualized by schlieren imaging, the in-cylinder flow by particle image velocimetry, the fuel/air-mixing by laser-induced fluorescence (at only one image per cycle), and combustion additionally via the chemiluminescence of the hydroxyl-radical. This sub-project collaborates particularly closely with those sub-projects that investigate the supersonic hydrogen-injection and that look at in-cylinder flow, mixing, and combustion with spatiotemporally highly resolved multi-dimensional simulations.
DFG Programme
Research Units
Major Instrumentation
Hochgeschwindigkeitskamera
