Experimental and numerical analysis of fuel flow in the diesel engine injection nozzle

The geometry of the diesel fuel injection nozzle and fuel flow characteristics in the nozzle significantly affects the processes of fuel atomisation, combustion and formation of pollutants emissions in a diesel engine. In this paper numerical and experimental results of the nozzle fuel flow analysis for a four-hole injection nozzle Bosch DLLA 148 S 311376 are presented. To describe the nozzle fuel flow, a three-dimensional computational fluid dynamics (CFD) model is employed. The CFD package FIRE (AVL Graz) is used for computation. The results represent the fuel flow characteristics for steady state flow conditions at different needle opening. For this purpose several three-dimensional models representing different needle lifts are made. The experimental results are obtained by measuring the fuel flow coefficients at steady state conditions on the nozzle flow tester made in Engine research laboratory (ERL) at the Faculty of mechanical engineering in Maribor. The fuel injection pump is driven by an electric motor, the pressure control valve regulates the pressure at 100 bar and the calibration fluid is injected through the nozzle into the measuring Plexiglas cylinder. The fuel flow coefficients obtained from the experimental results at steady flow conditions in the nozzle are compared with the results of the CFD analysis.