Gas Dynamics of Spark-Ignited Pre-Chamber Assisted Engine: PIV Study 2022-01-1047

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.