Rotary Engine Performance Limits Predicted by a Zero-Dimensional Model

A parametric study was performed to determine the performance limits of a rotary combustion engine. This study shows how well increasing the combustion rate, insulating and turbocharging increase brake power and decrease fuel consumption. Several generalizations can be made from the findings. First, it was shown that the fastest combustion rate is not necessarily the best combustion rate. Second, several engine insulation schemes were employed for a turbocharged engine. Performance improved only for a highly insulated engine. Finally, the viability of turbocompounding and the influence of exhaust port shape were calculated.

Rotary engine performance was predicted by an improved zero-dimensional computer model based on a model developed at the Massachusetts Institute of Technology in the 1980s. Independent variables in the study included combustion heat release rate, manifold pressures, wall thermal properties, leakage area and exhaust port geometry. Additions to the computer program since its results were last published include turbocharging, manifold modeling and improved friction power loss calculation. The baseline engine for this study is a single rotor 650 cc direct-injection stratified-charge engine with aluminum housings and a stainless steel rotor. Engine maps are provided for the baseline and turbocharged versions of the engine.