Direct Fuel Injection - A Study of Injector Requirements for Different Mixture Preparation Concepts

The first part of the paper outlines the main potential advantages of the direct fuel injection concept and describes the overall layout of a system in which the keystones are a piston rotary fuel delivery pump with integrated pressure regulation and electromechanical fast responding fuel injectors. Three different nozzle designs are discussed, a divergent pintle solid cone, a pintle hollow cone swirl layout and a closed cap multijet design.

In the second part of the paper the used experimental high pressure dynamic test equipment is discussed. Then the results obtained by the use of phase illuminated visualisation techniques and phase Doppler analysis as well as by a 3D CFD approach are presented.

The paper concludes by relating the spray patterns and the associated droplet penetration velocities, produced by the different nozzle types, to the combustion chamber layout and to the possible manufacturing precision requirements for each nozzle type.