Gas Dynamics of Spark-Ignited Pre-Chamber Assisted Engine: PIV Study

In recent years lean-burn technologies have acquired center stage in engine research due to stringent emission norms. Among such technologies, pre-chamber assisted combustion (PCC) has gained much attention for its ability to allow ultra-lean engine operation (λ > 2). The spark-ignited pre-chambers engines allow such lean operation by inducing a strong charge stratification, enhancing turbulence generation, and multipoint ignition. Adding a pre-chamber igniter to the engine alters the in-cylinder flow fields as mass is exchanged between the pre-chamber and the main chamber. This study reports the main chamber flow fields of methane fuelled heavy-duty optical engine fitted with a narrow throat active prechamber. Particle image velocimetry (PIV) at 10 Hz is performed from the side view using TiO2 particle seeding. PIV during motoring operation of the engine shows the inflow of main chamber charge into pre-chamber during compression stoke with flow velocities up to 8 m/s (close to the nozzle orifice). PIV measurements obtained by fuelling only the pre-chamber allow for studying the pre-chamber jet's interaction with the main chamber. The prechamber jet exhibits higher than 200 m/s initial velocities. The jet-induced turbulence in the main chamber was visualized, and the movement of the jet-feeding vortex was reported.