Abstract:

The effects of dynamic fluctuations of needle movement and hydraulic pressure on flow characteristics inside the nozzle hole and atomization characteristics outside the nozzle hole for multi-hole injector were investigated by numerical simulation. Results demonstrate that the flow characteristics and atomization characteristics change significantly with respect to the actual fluctuations of hydraulic pressure and needle movement inside the nozzle. The spray morphology and spray characteristic parameters, such as penetration distance and spray angle, are more consistent with the experimental results with the introduction of dynamic fluctuations of hydraulic pressure and needle movement inside the nozzle. The penetration distance is obviously larger and the spray angle is relatively smaller at the early injection stage when the hydraulic pressure and needle movement are taken as constants. Therefore, the influences of dynamic fluctuations of needle movement and hydraulic pressure on fuel flow inside the nozzle, atomization outside the nozzle, as well as on mixing, combustion and emission generation should be fully taken into consideration in diesel engine simulation.

Key words: power and machnery engineering, diesel injection nozzle, needle movement, variations of hydraulic pressure, fuel flow characteristics, spray