Andrew Swantek, Postdoctoral Appointee, Argonne National Lab, US , Daniel Duke, Christopher Powell, Alan Kastengren

Recently, single shot measurements at Argonne National Laboratory’s Advanced Photon Source have provided insight into the nature of fluctuations resulting from shot-to-shot variations in single-hole diesel injectors. These shotto- shot variations represent incoherent fluctuations in the mass of the fuel in the path of the beam, and are indicative of stochastic spray atomization and mixing. Fluctuations have spatial and magnitude dependencies on injection pressure, ambient pressure, and, to a lesser degree, nozzle hole size. In the current work, we perform a proper orthogonal decomposition (POD) analysis during the steady spray of these same single shot data to complement the previous analysis. POD analysis decomposes a set of potentially correlated mass data into components which are uncorrelated to all other modes. This serves to indicate regions of the spray with coherent, repeatable fluctuations (though not necessarily in phase from shot to shot). Shot-to-shot variation analysis indicates that incoherent/stochastic fluctuations are strongest several millimeters (> 2-5 mm) downstream of the nozzle. In contrast, the POD analysis reveals that the coherent, although much smaller in magnitude, fluctuations occur in the region very near to the nozzle (< 2 mm). Several conditions are investigated and a simplistic physical description is explored. We lastly examine the shot-to-shot variation in mean mass during the steady spray at a single spatial location near to the nozzle exit. These values are observed to have significant trends with diameter, rail pressure, and ambient pressure.

ILASS-AMERICAS 2015

Contact Name:

aswantek@anl.gov