Abstract:

To improve the shape of the reentrant combustion chamber of a highpressure commonrail directinjection diesel engine, 3D CFD simulations were performed using the software FIRE to investigate the effect of the combustion chamber geometry on the incylinder flow field characteristics. The microscopic characteristics of the airfuel mixture formation process as well as the effect of the fuel spray on the flow field, airfuel ratio field, and temperature field were studied as the reentrant combustion chamber matched with different fuel injection parameters. The results show that in the improved combustion chamber, it can make full use of the kinetic energy of the fuel spray to increase the intensity and the preserving ability of the air flow, thus enhance the airfuel mixing during the combustion period, promote the diffusion combustion process. Therefore, the reasonable combustion chamber shape matched with the appropriate fuel injection timing and pressure can effectively improve the efficiency and reduce the exhaust emissions of the highpressure commonrail directinjection diesel engine.

Key words: power machinery and engineering, DI diesel engine, high pressure common rail, reentrant combustion chamber, numerical simulation, flow field, spray