Combined effect of intake pipe deflection and injection timing on In-cylinder flow and combustion characteristics of a gasoline direct injection Wankel rotary engine

Abstract

To improve the fuel–air mixing and burning processes in a rotary gasoline engine to achieve efficient combustion, this paper used a computational fluid dynamics method to establish numerical simulation models for the in-cylinder flow and combustion of the rotary engine with a peripheral intake system. The effects of the intake pipe deflection angle and fuel injection timing on the in-cylinder flow, fuel distribution, and combustion characteristics were studied. The results showed that deflecting the intake pipe to the left generated a stronger tumble flow in the cylinder to effectively increase the turbulence intensity. A greater deflection angle provided a more obvious improvement. Moreover, deflecting the intake pipe to the left made the fuel distribution more towards the rear part of the combustion chamber and a more uniform fuel distribution in the cylinder. The spray impingement effect on the rotor surface was also greatly improved. Fuel injection timing also has a great impact on the mixing process of the combustible mixture in the cylinder. More advanced fuel injection timing resulted in longer mixing time of the fuel and air to make the mixture more uniform. Finally, deflecting the intake pipe to the left significantly increased the in-cylinder peak pressure and improved accumulated heat release. However, these effects became weakened when the fuel injection timing was retarded. Particularly, when the intake pipe was deflected to the left by 10°, the in-cylinder peak pressure increased most with a 27.9% increase compared with the original design. When the intake pipe was deflected to the left by 30°, the turbulent kinetic energy increased most with a 93% increase compared with the original design. The intake pipe was deflected by 10° to the left and the fuel injection timing was 250° CA BTDC, which is the most helpful for improving engine performance. This study can provide guidance for design of the injection and intake systems of the rotary engine.