This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
The Effect of Fuel Spray Momentum on Performance and Emissions of Direct-Injected Two-Stroke Engines
Technical Paper
2004-32-0013
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
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. White light images of the fuel sprays were recorded and analyzed. The test results were used to evaluate an existing KIVA spray model. The model provides a good match for quiescent conditions and it captures the trends of the effect of drop size and counter-flow on penetration. However, the spray model quantitatively under-predicts those effects into higher velocity counter-flows. Spray and engine test data show that sprays with smaller droplets and less spray momentum are more sensitive to the scavenging pattern than sprays with larger droplets and more momentum. If the spray momentum is not large enough, Hydrocarbon emissions can increase significantly due to increased mixture short-circuiting despite the improved fuel vaporization. Similar trends were predicted by CFD modeling with KIVA.
Recommended Content
Authors
Topic
Citation
Strauss, S. and Zeng, Y., "The Effect of Fuel Spray Momentum on Performance and Emissions of Direct-Injected Two-Stroke Engines," SAE Technical Paper 2004-32-0013, 2004, https://doi.org/10.4271/2004-32-0013.Also In
References
- Zhao F. Lai M. Harrington D.L. “A Review of Mixture Preparation and Combustion Control Strategies for Spark-Ignited Direct-Injection Gasoline Engines” SAE 970627
- Xu M. Markle L.E. “CFD-Aided Development of Spray for an Outwardly Opening Direct Injection Gasoline Injector” SAE 980493
- Lefebvre A.H. “Atomization and Sprays” Hemisphere Publishing Corporation 1989
- Sogama M. Kato M. “Development of the High Pressure Direct Injection (Hpdi) System for Two-Stroke Outboard Motor” SAE Paper 2001-01-1786
- Strauss S. Zeng Y.B. “Optimization of the E-TEC™ Combustion System for Direct-Injected, Two-Stroke Engines Toward 3-Star Emissions” SAE 2003-32-0007
- Zeng Y.B. Strauss S.S. “Modeling of Scavenging and Plugging in a Twin-Cylinder Two Stroke Engine Using CFD” SAE 2003-32-0020
- Zeng Y.B. Strauss S.S. “Modeling of Air-Fuel Mixing in a Two-Stroke Direct Injection Engine” SAE 2003-01-3103
- O'Rourke P. J. Amsden A. A. “The TAB Method for Numerical Calculation of Spray Droplet Breakup” SAE 872089
- Hinze J.O. “Fundamentals of the Hydrodynamic Mechanism of Splitting in Dispersion Processes” AIChE J. 1 3 1955 289 295
- Sevik M. Park S.H. “The Splitting of Drops and Bubbles by Turbulent Fluid Flow” J. Fluids Eng. 95 1973 53 60