Modeling Dynamic Behavior of Diesel Fuel Injection Systems 2004-01-0536

Precise control of fuel delivery and injection pressure is essential in modern DI diesel engines. Electronically controlled high-pressure injection systems provide features required by modern diesel engines such as precise injection quantity, flexible injection timing, flexible rate of injection with multiple injections and high injection pressures. A comprehensive experimental and numerical investigation has been performed to determine the influence of operating parameters and critical injector design parameters on the dynamic performance of advanced high-pressure electronically controlled diesel injection systems. The injection systems compared in this study are the High Pressure Common Rail (HPCR) and the Hydraulic Electronic Unit Injector (HEUI).

Experiments are carried out using a Bosch type injection-rate meter. Needle lift, injection-rate/rate shape, and injection pressure are measured. The dynamic effects of critical injector design parameters are characterized using a commercial modeling program. Also, CFD (Computational Fluid Dynamics) analysis is carried out to study dynamic flow characteristic effects in the needle seat region and its effect on the nozzle injection characteristics.

The needle lift characteristics show that the measured injection-rate is a strong function of injection pressure and nozzle hole diameter. The simulations provide useful information for further detailed studies of diesel injection system characteristics.