Limiting Delivery Ratio Curves of Crankcase-Scavenged 2-Stroke Cycle Engines by Throttling the Inlet Port

In order to obtain the limiting delivery ratio curve, the relationships between the delivery ratio and the engine speed were investigated on crankcase-scavenged 2-stroke cycle engines by varying through wide limits the effective angle-areas Fia(e) of the inlet ports.

It was found that the mean inlet Mach number Mim, already reported by the authors using 4-stroke cycle engines, showed well the characteristics of the limiting delivery ratio, and when Mim approached a limiting value the delivery ratio decreased hyper-bolically with an increase in engine speed.