Drop-size measurement techniques for sprays: comparison of Malvern laser-diffraction and Aerometrics phase/Doppler

The purpose of this paper is to compare the drop sizing results of an Aerometrics phase/Doppler particle analyzer with those of a Malvern laser-diffraction instrument. Measurements were performed on a small pressure-swirl atomizer. Since the laser-diffraction instrument measures a line-of-sight average through different regions of the spray while the phase/Doppler instrument characterizes the spray in a small volume, a conversion procedure was necessary prior to comparison. After conversion to equivalent forms, the point-measured average drop sizes exhibited similar trends throughout the spray, but the phase/Doppler values were generally larger. The total volume flow rate measured by the phase/Doppler instrument was inconsistent at different axial locations but significantly larger than the actual value at most locations.