Technical Paper
Application of Homogeneity Factor to Investigate the Effects of Pilot Fuel Injection in a High Speed Direct Injection (HSDI) Diesel Engine
2017-03-28
2017-01-0702
The simultaneous effects of pilot fuel quantity and pilot injection timing on engine performance and amount of pollutant emission have been computationally investigated in a High Speed Direct Injection (HSDI) diesel engine. In this study, a modified parameter called “Homogeneity Factor of in-cylinder charge (HF)” has been applied to analyze the air-fuel mixing and combustion processes. For this purpose, the simulated results has been firstly compared with the experimental data and a good agreement has been achieved for simulating the in-cylinder pressure and the amount of pollutant emissions. Then, nine different strategies based on two variables (the amount of fuel mass in pilot and main injection as well as the dwell between two injections) have been investigated. The results show that employing pilot injection results in higher in-cylinder temperature and shorter auto-ignition delay which causes a rapid increase in the rate of NOx formation in early stage of combustion process.