Combustion characteristics and performance analysis of a heavy-fuel rotary engine by designing fuel injection position

Abstract

The heavy fuel rotary engine commonly operates under high-pressure direct injection, lean-burn and spark-assisted ignition modes, this characteristic feature further highlights the significance of the distance between fuel injection position (FIP) and assisted spark plug in engine combustion organization and performance improvement. Thus, a computational fluid dynamics (CFD) means coupled with chemical reaction kinetics is used to investigate the FIP effects on the fuel stratification rule and combustion performance of a heavy-fuel rotary engine. Meanwhile, the flow and combustion transient information in the narrow combustion chamber is analyzed by considering five specially designed FIPs, whose distances to the assisted spark plug along the X-axis (major axis) are 25, 30, 35, 40 and 45 (mm). The results indicate that the distance increases to 40 mm (FIP-40) and 45 mm (FIP-45), the fuel stratified distribution rule is more rational, the mixture burn rate accelerates, combustion time reduces, and combustion performance improves significantly. The FIP-45 scheme is the preferred engineering application scheme after comprehensively assessing engine performance parameters, and when compared to the FIP-35 (original scheme) its peak cylinder pressure (Pmax) increases by 5.3 %, CA10-90 accelerates by 20.4 %, and main emissions of Soot, NO and CO reduce by 48.1 %, 50.0 % and 36.2 % respectively, while CO2 increase.