CFD modelling and analysis of the passive pre-chamber ignition concept for future generation spark-ignition engines
- Autores: Ibrahim Ignacio Barbery Avila
- Directores de la Tesis: Ricardo Novella Rosa (dir. tes.)
- Lectura: En la Universitat Politècnica de València ( España ) en 2023
- Idioma: español
- Tribunal Calificador de la Tesis: Raúl Payri Marín (presid.), María Dolores Redel Macías (secret.), Cinzia Tornatore (voc.)
- Programa de doctorado: Programa de Doctorado en Sistemas Propulsivos en Medios de Transporte por la Universitat Politècnica de València
- Materias:
- Enlaces
- Tesis en acceso abierto en: RiuNet
- Resumen
Since the irruption of electric vehicles in the automotive market as a clean and affordable transportation option, engine manufacturers have been looking for new ways to reduce the environmental footprint of current internal combustion engines (ICE's). Nowadays, most of the research efforts in passenger car applications focus on further developing spark-ignition (SI) engines to promote a new generation of high-performance and sustainable powertrains.
In this context, the pre-chamber ignition concept is becoming an attractive solution to increase the thermal efficiency of future light-duty SI engines, due to its inherent capability of enhancing the combustion process. Moreover, combining this ignition strategy with diluted mixtures (either with air or exhaust gases) has the potential to further improve the engine performance and reduce pollutant emissions. In particular, compared to active pre-chamber systems with an auxiliary fuel supply, the passive version provides advantages in terms of mechanical simplicity, packaging and cost-effectiveness. However, there are still major hurdles related to the understanding of the fundamental physicochemical aspects of the concept (turbulence, scavenging, energy conversion, jet dynamics, pre-chamber geometry...), that ultimately have limited the integration of this technology into production vehicles.
Therefore, this doctoral thesis intends to fill these knowledge gaps by using a state-of-the-art CFD model, validated with an extensive set of engine tests and following a simulation methodology specially developed for this research work. The obtained results were divided into three parts:
The first part evaluated a research single-cylinder SI engine, representative of light-duty applications, operating with the passive pre-chamber system in un-diluted stoichiome\-tric conditions. Here, the impact of the engine operating point, spark timing and pre-chamber geometry over the physical and thermochemical processes that are involved in this combustion concept were evaluated.
The second part of the study focused on characterizing the concept in diluted conditions with air and exhaust gas re-circulation (EGR). The combustion evolution and energy distribution in the pre-chamber and main chamber for the experimental dilution limits were deeply analyzed. In addition, the use of hydrogen to extend the air-dilution limit was also assessed.
The final part of the investigation consisted in developing a potential technological application of this ignition concept from the acquired knowledge. Therefore, a pre-chamber design methodology combining 0D/1D and CFD numerical tools was developed and validated in the engine test bench. The resulting pre-chamber offered good levels of thermal efficiency and was able to extend the EGR dilution limit.
This doctoral thesis represents a significant advancement in the frame of analyzing the impact of advanced ignition systems and their integration in ICE's in general, and in SI engines in particular, with the aim of improving the global features of these powerplants (efficiency and emissions), contributing to the effort that the scientific community is carrying out to mitigate the environmental impact of the transportation sector.
