Stratified Scavenging In 2 cycle Engines ME 433

Stratified Scavenging In 2 -cycle Engines ME 433 Combustion Engine Systems Project Presentation Presented by: Eric Henderson July 31, 2013

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

Introduction ØWhat is scavenging? ØScavenging consequences ØHigh HC emissions ØPoor fuel economy

Stratified Scavenging Concept ØLarge concentration of emissions at beginning of scavenging process ØReduce short-circuiting by providing a barrier of air between incoming charge and exhaust gases

Stratified Scavenging Methods Air-Head Method ØFundamental method ØProvides a cushion of air on top of the charge ØAir is short-circuited instead of charge

Stratified Scavenging Methods Stratified Charge Injection ØMultiple ports required ØProvides a curtain of air or lean charge between the rich charge and exhaust gases

Stratified Scavenging Methods Compressed Air Assisted Injection (CAAI) ØUses motion of piston and dynamics of engine gases ØPressure pulse created in injection tube used to inject charge ØLean mixture layer between charge and exhaust gases

Stratified Scavenging Methods Multi-Layer Stratification (Mu. LS) ØCombines advantages of other methods ØLayers consist of air, lean charge, and rich charge

Concluding Thoughts ØSignificant reduction in HC emissions achieved ØFuel economy (BSFC) improved ØChallenges to overcome ØProper fuel-air ratios ØMaintain power while reducing emissions ØMaintain sufficient lubrication

References Mc. Elligott, 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 (Mu. LS) 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.

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