Technical Paper
The Effect of Fuel Spray Momentum on Performance and Emissions of Direct-Injected Two-Stroke Engines
2004-09-27
2004-32-0013
In recent years, it has been demonstrated that E-TEC direct injected two-stroke engines are capable of meeting the toughest emissions standards for marine outboard engines. Proper in-cylinder mixture distribution and preparation are essential for achieving low emissions, high performance, and good run-quality. The mixture distribution is driven largely by the momentum exchange between the fuel spray and the scavenging flow. It has been found that different engines can exhibit significantly different behaviors with similar fuel sprays. This difference is attributed to the difference in scavenging flow patterns and its effect on the momentum balance between the fuel spray and the air flow. In order to investigate this phenomenon, a test fixture was designed and built to evaluate fuel sprays into air-counter-flows with velocities of up to 40m/s by recording spray images and measuring spray penetration. Two different sprays were tested in the fixture and in a variety of engines.