Study of a common rail fuel injection system 2001-01-3184
This research work deals with common rail fuel injection system of a diesel engine. Fuel injection system tuning is important to provide similar conditions to each injections. This means that the timing of the fuel injection and control of the amount of the fuel during the injection have to be done accurately. The pressure oscillations might disturb the behaviour of the fuel injection event if the system is not properly designed or tuned. In this work the pressure oscillations and how to prevent them were studied.
The study started with the modelling of the components of the Common Rail fuel injection system. The simulation results were verified to measured ones. After the fluid properties were also taken into account the correspondense were acceptable. The simulation model were used for studying the performance a Common Rail fuel injection system.
This study deals also with the fluid properties in high pressure. Normally, interest is restricted to components as valves when researching fuel injection systems. The fluid itself is kept in a secondary role. The increasing system pressure means that the fluid must be considered as a component with variable properties. In this study the bulk modulus, density and sonic speed has been defined as a function of pressure. The method used in this case is based on the determination of the time delay between two pressure sensors. The studied pressure range was 200 ñ 1450 bar.
In the simulation results the injected volume and injection pressure are shown as a function of injection time. Following fluid properties were also presented as a function of pressure; bulk modulus, density and sonic speed.
In addition two different types of Common Rails and two lenghts of rails were considered. The main point for these measurements was to use the calculated bulk modulus, density and sonic speed values and examine the suitability of these to determined fuel properties in different fuel injection system. Also the behaviour differences of these two different rail types were studied.
