Parameters optimization of prechamber jet disturbance combustion system—Effect of prechamber volume and fuel injection mass ratios on performance and exhausts in a diesel engine

Abstract

Experiment combined with numerical simulation were used to investigate influences of prechamber volume ratio (PVR) and fuel injection mass ratio (PFR) on performance and emissions of a prechamber jet disturbance combustion system in a diesel engine at heavy load. By parameter optimization, the conclusions revealed that, during the compression stroke, the swirl inside the prechamber can make the fuel entrain more air, leading to more complete burn and reduced exhausts; the jet flame formed during early combustion period collides with the main combustion spray, promoting the flame to develop around, which intensifies the disturbance to the surrounding flow field, improving the indicated thermal efficiency (ITE_g) (carbon reduction); during late combustion period, the jet kinetic energy continued into the main chamber from the prechamber causes the oil attached to the wall of the main chamber to be peeled off into the cylinder and then mix and burn, helping increase the ITE_g, and further decrease the soot and CO emissions. It was found that, compared with the original diesel engine, by adding a prechamber and optimizing the prechamber parameters (the optimized PVR/PFR is 3 %/2 %), the performance and emissions characteristics are improved: the ITE_g is improved by 6.41 %, the NO_x, soot and CO exhausts are deceased by 2.8 %, 44.4 % and 46.3 %, respectively.