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The success obtained by use of Virtual Engine Modeling (VEM) in the design and development areas of fuel injectors generated a lot of interest from production and quality engineers to possess a similar tool related to spray vessel measurements. To respond to stringent PL6/EURO5 requirements it was decided to develop a Virtual Spray Vessel (VSV) tool capable of predicting spray patterns and perform droplet diameter analysis comparable to real-time Phase Doppler Analysis (PDA) results. The paper describes the analogies between VEM and VSV modeling and the specific new numerical approaches to obtain spatial spray data comparable to conventional mechanical measurement techniques and to perform droplet diameter analysis comparable to PDA data. The paper concludes with a series of comparisons of simulated and experimental data from virtual and real-time measurement vessels.

The paper presents a study of the influence of fuel pressure supply fluctuations on the upstream side of the fuel injector atomizer. The study is performed over a wide range of pressures (70 to 130 Mpa) with two different common-rail (CR) high-pressure fuel injectors. The common atomizer is a VCO-type equipped with conically shaped atomizer bores. With the injector tip (nozzle) mounted in a counter-pressure vessel the pressure fluctuations in the fuel-rail and in the injector body are recorded simultaneously with stroboscopic Schlieren-visualization of the time-resolved spray behavior. It is demonstrated that not only the instantaneous mass flow is affected. As a function of rail-pressure, pulse-width and injection strategy the pressure fluctuations change the spray hard-core structure and its break-up behavior.