Study of the Impact on the Combustion Process of Injector Nozzle Layout creating Enhanced Secondary Spray Break-up

The paper presents a study of a key-element in the mixture preparation process. A typical common-rail (CR) high-pressure fuel injector was fitted with a prototype injector nozzle with atomizer bores of a particular conical layout. It is demonstrated within certain layout limits, that a considerable enhancement can be obtained for the secondary break-up of the hard-core fluid sprays produced by the nozzle. The impact on the combustion process is examined in terms of pressure and heat release as well as of the engine-out pollutant emission. The results are compared to those of an earlier developed CR high-pressure injector nozzle.

The atomization behavior of the prototype nozzle is illustrated through experimental results in terms of engine-out emissions from a 1.3-liter turbo-charged passenger car diesel engine. The detailed spray behavior is visualized on a component test rig by use of specially developed optical visualization techniques. Furthermore analytical considerations of the secondary break-up mechanics are highlighted by the use of a 3D-numerical simulation code NCF-3D.

The paper concludes with a discussion of the improvement, which can be expected from this type of atomization layout as well as the production processes necessary for its mass production.