A three-dimensional model of stratified scavenging engine was established to study the scavenging characteristics and working mechanism of stratified scavenging engine

then three-dimensional CFD software Fluent was used to simulate and analyze the fluid structure with or without stratified scavenging system at rated speed

and the boundary conditions required for its calculation were obtained by one-dimensional simulation calculation of the engine. Results showed that

the stratified scavenging engine used pure air to form a stratification between the fresh mixture and the exhaust gas during operation

a part of the scavenging loss was taken by the pure air

which reduced 15% of unburned hydrocarbon and improved the fuel economy of the engine; the stratified scavenging engine and the non-stratified scavenging engine had a scavenging efficiency of 75%

without significant effect on the scavenging efficiency. The results of the research can provide reference for the design of stratified scavenging engines.