Stratified Scavenging In 2-cycle Engines

1. Stratified Scavenging In 2-cycle Engines ME433 Combustion Engine Systems Project Presentation Presented by: Eric Henderson July 31, 2013

2. Overview • Introduction • Stratified Scavenging Concept • Stratified Scavenging Methods • Air-Head Method • Stratified Charge Injection • Compressed Air Assisted Injection • Multi-Layer Stratified Method • Concluding Thoughts • Questions

3. Introduction • What is scavenging? • Scavenging consequences • High HC emissions • Poor fuel economy

4. Stratified Scavenging Concept • Large concentration of emissions at beginning of scavenging process • Reduce short-circuiting by providing a barrier of air between incoming charge and exhaust gases

5. Stratified Scavenging Methods Air-Head Method • Fundamental method • Provides a cushion of air on top of the charge • Air is short-circuited instead of charge

6. Stratified Scavenging Methods Stratified Charge Injection • Multiple ports required • Provides a curtain of air or lean charge between the rich charge and exhaust gases

7. Stratified Scavenging Methods Compressed Air Assisted Injection (CAAI) • Uses motion of piston and dynamics of engine gases • Pressure pulse created in injection tube used to inject charge • Lean mixture layer between charge and exhaust gases

8. Stratified Scavenging Methods Multi-Layer Stratification (MuLS) • Combines advantages of other methods • Layers consist of air, lean charge, and rich charge

9. Concluding Thoughts • Significant reduction in HC emissions achieved • Fuel economy (BSFC) improved • Challenges to overcome • Proper fuel-air ratios • Maintain power while reducing emissions • Maintain sufficient lubrication

10. References McElligott, S., Douglas, R., Kenny, R. G., “An Assessment of a Stratified Scavenging Process Applied to a Loop Scavenged Two-Stroke Engine,” SAE Technical Paper Series , Small Engine Technology Conference and Exposition, Madison, Wisconsin, September 28-30, 1999. Mavinahally, N., Veerathappa, J., Rajgiri, S., and Mavinahalli, V., "Multi-Layer Stratified (MuLS) Two-Stroke Engine," SAE Technical Paper Series, 2012-32-0119, 2012. Golsborough, S. S., Blarigan, P., V., “Optimizing the scavenging system for a two-stroke cycle, free piston engine for high efficiency and low emissions: A computational approach,“ SAE Technical Paper Series, 2003-01-0001, 2003, pp. 1-20. Yoshida, Y., Uenoyama, K., Kawahara, Y., Kudo, K., “Development of stratified scavenging two-stroke cycle engine for emission reduction,” SAE Technical Paper Series, 1999-01-3269, 1999, pp. 1278-1285. Zahn, W., Rosskamp, H., Raffenberg, M., Klimmek, A., “Analysis of a stratified charging concept for high-performance two-stroke engines,” SAE Technical Paper Series, SAE 2000 World Congress, March 6-9, 2000. Kobayashi, B., Sawada, T., Zama, R., Ogura, N., Wada, S., “Investigation of port design for small air-head stratified scavenging two-stroke cycle engine,” Society of Automotive Engineers of Japan, 2005-32-0012, 2012. Hill, B.W., “Stratified-charging applied to two-stroke engine,” Automotive Engineering, Vol. 91, Issue 9, 1983, pp. 55-56.

11. Questions?