Effect of Inlet Structure on Tumble Intensity and Combustion Process of Hybrid Gasoline-direct-injection Engine

Abstract:

Based on a 1.5L hybrid turbocharged direct injection gasoline engine. The effects of different inlet structures on in-cylinder steady and transient tumble intensity and combustion performance were studied by using steady-state inlet test bench and 3D simulation tools. 4 different kinds of inlet were designed in this research. They were compared on a steady-state airway testing system with the simulation results. The in-cylinder transient tumble ratio， transient turbulent kinetic energy （TKE）， velocity distribution， air/fuel ratio and flame front of different inlet crank angle were calculated by simulation. The results showed that higher tumble ratio would improve the in-cylinder fuel air mixing and increase the average TKE at ignition phase， which affected the flame propagation velocity. Then it affected the in-cylinder combustion and performance of the GDI engine.

Key words:gasoline-direct-injection engine（GDI) engine;inlet optimization;tumble intensity;combustion characteristic