Assessment of Scavenging Models for Small Two Stroke Cycle Engines

A detailed assessment of the various models proposed to simulate the scavenging process in two stroke cycle engines has been made by comparing the charging efficiency and fresh charge fraction in the exhaust gas predicted by the various models. The effect of delivery ratio on the charging efficiency has been studied in detail using different models. It is recommended that a simple two phase model consisting of 50 percent perfect displacement and 50 percent perfect mixing may be used as a satisfactory approximation of the scavenging process.

The effect of charge stratification in improving the fuel economy of two-stroke engines has been examined and an analytical preidction of the effect of charge stratification on reduction in fuel loss has been presented.