Numerical Simulation on Forced Swirl Combustion Chamber in Diesel Engine

摘要

A concept of forced swirl combustion chamber in diesel engine is proposed in this paper. It can be used to enhance the intensity of swirl flow in the cylinder and accelerate the rate of air-fuel mixture process by designing the special structure in the combustion chamber. This new type of forced swirl combustion chamber includes double swirl combustion chamber that was discussed past and partial swirl combustion chamber that is mentioned in this paper. Firstly, the calculative result of double swirl combustion chamber by CFD code FIRE is calibrated by the method of Validation & Verification with experiment data. By the effect of the special structure of the ridge and slope in partial swirl combustion chamber, the rate of air-fuel mixture and combustion process has been accelerated twice by comparing with the calculative result of these two combustion chambers. At the same time, the utilization of air in squish zone has been improved. The characteristic of double-peak has appeared within main combustion duration on the instantaneous heat release rate curve of partial swirl combustion chamber. The result of calculation shows that NOx and soot mass fraction of partial swirl combustion chamber is lower than that of double swirl combustion chamber by 8.2 and 7.4 percent respectively, and indicated heat efficiency is 2.2 percent higher.