Effects of In-Cylinder Flow Structures on Soot Formation and Oxidation in a Swirl-Supported Light-Duty Diesel Engine

Some previous research results have shown that EGR (exhaust gas recirculation) rate, pilot fuel quantity, and main injection timing closely associated with engine emissions and fuel consumption. In order to understand the combined effect of EGR rate, pilot fuel quantity, and main injection timing on theNOx(oxides of nitrogen), soot, and ISFC (indicated specific fuel consumption), in this study, CFD (computational fluid dynamics) simulation together with the Taguchi method and the ANOVA (analysis of variance) technique was applied as an effective research tool. At first, simulation model on combustion and emissions of a light duty diesel engine at original baseline condition was developed and the model was validated by test. At last, a confirmation experiment with the best combination of factors and levels was implemented. The study results indicated that EGR is the most influencing factor onNOx. In case of soot emission and ISFC, the greatest influence parameter is main injection timing. For all objectives, pilot fuel quantity is an insignificant factor. Furthermore, the engine with optimized combination reduces by at least 70% forNOx, 20% in soot formation, and 1% for ISFC, in contrast to original baseline engine.

Download Full-text

Investigation of fuel injection pattern on soot formation and oxidation processes in a light-duty diesel engine using integrated CFD-reduced chemistry

Fuel ◽

10.1016/j.fuel.2012.01.002 ◽

2012 ◽

Vol 96 ◽

pp. 404-418 ◽

Cited By ~ 27

Author(s):

Kar Mun Pang ◽

Hoon Kiat Ng ◽

Suyin Gan

Keyword(s):

Diesel Engine ◽

Fuel Injection ◽

Soot Formation ◽

Oxidation Processes ◽

Light Duty ◽

Reduced Chemistry

Download Full-text

Piston geometry effects in a light-duty, swirl-supported diesel engine: Flow structure characterization

International Journal of Engine Research ◽

10.1177/1468087417742572 ◽

2017 ◽

Vol 19 (10) ◽

pp. 1079-1098 ◽

Cited By ~ 16

Author(s):

Federico Perini ◽

Kan Zha ◽

Stephen Busch ◽

Eric Kurtz ◽

Richard C Peterson ◽

...

Keyword(s):

Diesel Engine ◽

Flow Structure ◽

Structure Characterization ◽

Flow Topology ◽

Optical Engine ◽

Light Duty ◽

Image Velocimetry ◽

Multiple Cycles ◽

Oriented Parallel ◽

Cylinder Flow

This work studied how in-cylinder flow structure is affected in a light-duty, swirl-supported diesel engine when equipped with three different piston geometries: the first two featuring a conventional re-entrant bowl, either with or without valve cut-outs on the piston surface and the third featuring a stepped-lip bowl. Particle image velocimetry experiments were conducted inside an optical engine to measure swirl vortex intensity and structure during the intake and compression strokes. A full computational model of the optical diesel engine was built using the FRESCO code, a recently developed object-oriented parallel computational fluid dynamics platform for engine simulations. The model was first validated against the measured swirl-plane velocity fields, and the simulation convergence for multiple cycles was assessed. Flow topology was studied by addressing bulk flow and turbulence quantities, including swirl structure, squish flux, plus geometric and operating parameters, such as the presence of valve cut-outs on the piston surface, compression ratio and engine speed. The results demonstrated that conventional re-entrant bowls have stronger flow separation at intake, hampering bowl swirl, but higher global swirl than for stepped-lip bowls thanks to a stronger and more axisymmetric squish mechanism and less tilted swirl. Stepped-lip bowls have larger inhomogeneities (tilt and axisymmetry) and higher turbulence levels, but also faster turbulence dissipation toward top dead center. They have weaker squish flux but larger squish inversion momentum as a result of the smaller inertia.

Download Full-text