Fundamentals for Optimizing the Use of Natural Gas in Diesel Engines

Abstract

For fueling diesel engines with gaseous fuels, combined gas/diesel in-cylinder injection systems have many advantages over traditional systems with carburetted manifolds. However, understanding mixing phenomena within an engine is difficult. Here, it has been studied in a rig under atmospheric conditions. Shadowgraph and schlieren techniques were employed to identify mixing regions between diesel and natural gas injected simultaneously into a chamber. The results were used to calibrate a CFD model for simulating injection into an engine's cylinder. The optimum orientation of the jets relative to each other was determined and then the best staging of the jets was estimated.

Notes

*At this time, the 10% contour of mass-fraction exceeded the bounds of the domain. Subsequent time-step intervals and flow rates were approximated based upon the development of the jet observed in the schlieren video.

¹The equivalence ratio of a system is defined as the ratio of the actual to stoichiometric fuel-to-air mixture strengths.