Applying the Homogeneity Factor to Evaluate the Effects of Pilot Injection Characteristics on Air-Fuel Mixing Quality and Engine Performance in a Turbo-Charged High Speed Direct Injection (HSDI) Diesel Engine

In current research, the simultaneous effects of pilot fuel quantity and pilot injection timing on air-fuel mixing process, engine performance and the amount of pollutant emissions have been investigated in a High Speed Direct Injection (HSDI) turbo-charged diesel engine. For this purpose, a modified parameter called “Homogeneity Factor (HF)” has been applied as a new measure for analyzing the air-fuel mixing process. The simulated results has been firstly compared with the experimental data and a very good agreement has been achieved for simulating the in-cylinder pressure, the heat release rate and the amount of pollutant emissions. The results show that the pilot fuel quantity is more effective on air-fuel mixing quality than pilot injection timing. By advancing the start of pilot injection timing, the maximum amount of Homogeneity Factor (HF) during pilot injection, is achieved at an earlier time. As a result, for earlier SOP timing, a sufficient mixing is available to achieve a more homogeneous at the time of ignition.