Study of the Impact of Variations in the Diesel-Nozzle Geometry Parameters on the Layout of Multiple Injection Strategy

In the present paper the impact of three different geometrical layouts of the discharge nozzle of a high-pressure diesel injector designed is examined for a common rail second generation direct injection system. The paper presents a comparative study of the spray behavior of the three different nozzle layouts connected to a 150 MPa rail-pressure when mounted on a 1.6 liter European passenger car engine. To evaluate experimentally the differences in the fundamental physical spray parameters several specially developed optical visualization techniques are used, which enable phase-Doppler, Laser-sheet and high-speed recordings of dense high pressure sprays.

The change in basic spray parameters (time-resolved droplet distribution and spray momentum) caused by the nozzle geometry variation is examined. The impact on the in-cylinder penetration and mixing characteristics is studied with a 3D-numerical simulation code NCF-3D.

The paper continues with a discussion of the interaction between nozzle layout and the use of a multi-strike injection strategy adopted in order to decrease the engine-out NO_x and particulate emissions.

The paper concludes with a discussion of the capability of each of the nozzle layouts to enhance the optimization of the multi-strike injection approach.