End of injection, mass expulsion behavior in single hole diesel fuel injectors


Andrew Swantek , Daniel Duke,F. Zak Tilocco,Nicholas Sovis,Christopher Powell,Alan Kastengren


The end of injection behaviors of diesel fuel injectors lack thorough understanding; however, they can influence engine emissions. In the current work, we use x-ray diagnostics to examine the behavior of single hole diesel injectors during the period of needle descent and post-closing. Internal x-ray phase contrast imaging of the nozzle and sac reveals injector motion and the appearance of ingested bubbles. External phase contrast imaging visualizes the packets of ejected fuel, “dribble,” after needle closing. Lastly, x-ray radiography is used to make quantitative measurements of the fuel field. Recent advancements at the 7BM beamline at Argonne’s Advanced Photon Source have allowed absorption measurements of single spray events. These offer insight into the stochastic nature of these sprays. We calculate ensemble standard deviations of the event as a measure of the fluctuations throughout the spray event. The three parameters varied in this work are: nozzle diameter, fuel rail pressure, and ambient gas pressure. We observe increased fuel expulsion with: increasing nozzle diameter, increasing rail pressure, and decreasing ambient pressure. Ambient gas density and pressure effects are decoupled by using two different gasses as the ambient environment. We observe that pressure, rather than density, controls the quantity of mass expulsion. Increased fuel expulsion also correlates with an increase in ingested bubbles.



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Andrew Swantek



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