Turbulent jet development of active pre-chamber fueled with zero-carbon fuel blends

Abstract

Active pre-chamber turbulent jet ignition has the potential to enhance the combustion of low-reactivity fuels. However, the related fundamental studies on the jet ignition mechanism are inadequate, especially for the independent effects of the zero-carbon fuel blends on the jet development characteristics, isolating the impact of the main chamber combustion. In this work, the effects of the fuel compositions ranged from the 30%H₂+70%NH₃ blend to pure H₂ and also comprised the pure CH₄ for comparison and the initial pressures in the pre-chamber are studied by the two-pass high-speed Schlieren method. The results show that the hot turbulent jet developments present great differences for the pre-chamber charged with various H₂+NH₃ blends across the hydrogen blend ratios varying from 30 % to 100 % in volumetric fraction. Moreover, the evolutions of the hot turbulent jet from the pre-chamber charged with the 50%H₂+50%NH₃ blend and pure CH₄ are similar. As the initial pressure increases, there is a gradual deceleration in the development of the pre-chamber jet, and the turbulent jet development characteristics depend on the pressure ratio rather than the pressure difference across the pre-chamber and main chamber. This study could provide important insights for the development of zero-carbon fuel engines.