Effect of operating conditions on soot-formation pathways in an optical direct-injection gasoline engine
[EN] Understanding the dynamics of soot-formation pathways is crucial for the foreseeable advancement of gasoline engines, which depend on optimizing a complex array of parameters to meet regulatory standards. This paper employs a comprehensive set of parameter changes to examine the sources of soot...
| Autores: | , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Universitat Politècnica de València (UPV) |
| Repositorio: | RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia |
| Idioma: | inglés |
| OAI Identifier: | oai:riunet.upv.es:10251/230299 |
| Acceso en línea: | https://riunet.upv.es/handle/10251/230299 |
| Access Level: | acceso embargado |
| Palabra clave: | Direct-injection spark-ignition engine Soot pathways Injector tip wetting Optical diagnostics 07.- Asegurar el acceso a energías asequibles, fiables, sostenibles y modernas para todos 13.- Tomar medidas urgentes para combatir el cambio climático y sus efectos |
| Sumario: | [EN] Understanding the dynamics of soot-formation pathways is crucial for the foreseeable advancement of gasoline engines, which depend on optimizing a complex array of parameters to meet regulatory standards. This paper employs a comprehensive set of parameter changes to examine the sources of soot formation observed in an optical direct-injection spark-ignition engine. By testing three injection pressures, three intake temperatures, five start of injection timings, and two engine loads, the study assesses their impact on soot formation and combustion characteristics. The analysis benefits from two distinct optical accesses, enabling a detailed portrayal of the flame morphology and the origins of sooting flames. Acquired images were supplemented by measured particle emissions, reinforcing the findings of the optical data. Transitioning from medium to high load led to an increase in particle emissions caused by a higher degree of injector tip wetting, as seen from the in-cylinder imaging. Increasing injection pressure reduced injector tip sooting, albeit leading to more spray-wall impingement at early injection timings. Under the earliest injection timing (-330 degrees CA), employing the lowest injection pressure (60 bar) reduced particle number and soot mass concentrations, with minimal impact on combustion performance. Intake temperature impacts fuel film quantity on both the injector tip and piston surface, with higher temperatures accelerating film evaporation from the bulk gas side. On the downside, it was necessary to retard combustion phasing at elevated intake temperatures to mitigate engine knock, consequently leading to a degradation in flame propagation speed and work output. The experiments also revealed a U-shaped trend in injection timing sweep, where spray-wall impingement dominates at the earliest timing, gas-phase in- homogeneities become more prominent at delayed timings, and injector tip soot is observed under all conditions due to injector fouling. The results of this study illuminate potential strategies for reducing engine-out particle emissions while maintaining satisfactory combustion performance, aiming to possibly obviate the necessity for gasoline particle filters. |
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