IDENTIFYING BURST SPLITTING EVENTS IN PHASE DOPPLER INTERFEROMETRY MEASUREMENTS

Burst splitting events, in which noisy environments result in a single droplet being counted as multiple droplets during phase Doppler interferometry (PDI) measurements, are investigated. The cause of burst splitting is discussed and compared with chattering, another phenomenon that results in overcounting of droplets in PDI measurements. Several techniques are presented to identify the occurrence of burst splitting events, and the impact of such events on the measurements is discussed. It is shown that burst splitting has a serious effect on volume flux measurements; however, the impact on size and velocity distributions is much weaker. The events significantly distort the probe volume correction, which is applied to the measured size distributions to remove the bias introduced by the size dependence of the probe area. Burst splitting events do not depend on the type of PDI processor used; however, it is shown that for frequency-domain processors, judicious choice of operating parameters can minimize the impact of burst splitting occurrences.