Experimental Investigation on Externally Scavenged S. I. Engine

Two stroke crank-cased spark ignition engines have high exhaust emissions and low brake thermal efficiency due to the short-circuiting losses and incomplete combustion, which occur during idling and at part load operating condition. During short-circuiting, fuel air mixture may be lost directly to the exhaust port resulting in increase in the raw pollutant emission with increase in fuel consumption. Externally scavenged engine is developed to eliminate the short-circuiting losses. In this research study, an attempt has been made to improve scavenging characteristics of two stroke engine. Experimental investigations have been carried out at various valve openings. Externally scavenged engine gives superior performance as compared with crank-cased engine. Performance parameters like BP, BSFC, delivery ratio, scavenging efficiency are also improved.