The Effect of Atmospheric Conditions on the Performance of an Air-Borne Two-Stroke Spark-Ignition Engine

Abstract

The effect of changes in atmospheric pressure and temperature on the performance of a crankcase-scavenged spark-ignition two-stroke cycle engine has been investigated. A detailed computer code has been developed to simulate the two-stroke cycle and was used to evaluate an optimal engine design for best performances at high altitude conditions. The model which includes detailed computations of the scavenging process, calculations of the flows into and out of the engine, empirical expressions for the combustion process, and a practical approach for the heat transfer has been calibrated by using experimental results. An empirical correlation has been devised for the prediction of the indicated power and for the specific fuel consumption of an engine at any pressure and temperature using information obtained at normal atmospheric conditions. These are [Formula: see text] The correlations have been compared with some other suggested correlations and were found to best fit experimental observations for three different makes of engine.