Experimental and Numerical Analysis of Passive Pre-Chamber Ignition with EGR and Air Dilution for Future Generation Passenger Car Engines 2020-01-0238
Nowadays the combination of strict regulations for pollutant and CO2 emissions, together with the irruption of electric vehicles in the automotive market, is arising many concerns for internal combustion engine community. For this purpose, many research efforts are being devoted to the development of a new generation of high-performance spark-ignition (SI) engines for passenger car applications.
Particularly, the pre-chamber ignition concept, also known as Turbulent Jet Ignition (TJI), is the focus of several investigations for its benefits in terms of engine thermal efficiency. The passive or un-scavenged version of this ignition strategy does not require an auxiliary fuel supply inside the pre-chamber; therefore, it becomes a promising solution for passenger car applications as packaging and installation are simple and straightforward. Moreover, combining this concept with EGR dilution is an interesting alternative for both improving the engine efficiency maintaining low pollutant emissions as this approach is perfectly compatible with the three-way catalyst for NOX control.
However, previous researches focused on developing the technology rather than understanding the governing physical phenomena. Consequently, the knowledge about the characteristics and limitations of the combustion process for this ignition concept is still limited. For this purpose, a CFD computational study was performed in this research work to analyze the TJI combustion features in a turbocharged passenger car SI engine. Single-cycle RANS simulations were carried out following a novel methodology and the results were validated against experimental data keeping the same engine configuration and operating conditions. An EGR sweep was performed extending beyond the limit measured in the experimental tests to study in detail the combustion process and jet characteristics. The analysis of the results provided a detailed insight about the key aspects limiting the passive pre-chamber concept compatibility with the EGR dilution strategy.
Ricardo Novella, Jose Pastor, Josep Gomez-Soriano, Ibrahim Barbery, Cedric Libert, Fano Rampanarivo, Chistou Panagiotis, Maziar Dabiri
Universitat Politecnica de Valencia, DEA-IRP Groupe Renault