Numerical and experimental investigation of common rail fuel injection system and evaluating influence of fuel pressure on injection characteristics and pressure fluctuations

The combustion processes, engine performance, fuel consumption, exhaust-gas composition, and combustion noise in the diesel engine are closely linked to appropriate mixture of air-fuel in combustion chamber. The fuel-injection parameters such as injection start point, discharge rate curve, injection time and injection pressure are defined by the quality of the mixture formation. The numerical modeling is the common method of investigation of fuel pressure and its effects on the injection quantity in the fuel system. In this study, one-dimensional common rail fuel injection system was simulated in AMEsim software. The simulation results illustrated that the higher injection pressure can lead to higher pressure fluctuations. Because of compressibility of fuel, its density increased with the increase of pressure, resulting in faster propagation of distribution in the whole high pressure tubes. The delay in closing the throat and moving the needle downwards, moreover, led to the difference between Injection time and solenoid stimulation in different pressures. Closing delay, also, increased with increasing pressure.