Exhaust emission control with direct multi-point fuel-injection of a small two-stroke engine

The recent study on fuel economy and emission control of a 50 cc two-stroke spark-ignition engine utilising direct-fuel-injection (DFI) is presented. A computer modelling code is used in the analysis of the scavenging and fuel-injection processes. The effect of the shapes of both the cylinder head and the piston crown is considered in the computational model. The DFI process is simulated as fuel droplets dispersed in a flow of continuous gas phase using the Lagrangian model. Fuel droplet distribution and fuel-vapour concentration are displayed for both single-point injection and two-point injection. A comparison with a computational model of a caburetted version of the engine suggests that UFI has significant advantages, not least the reduction of unburnt hydrocarbon emissions.