ID 134

Size-velocity pdfs for Drop Fragments Formed via Multimode Breakup

 

Abstract:

Understanding drop breakup will optimize aircraft engine performance, reduce agrochemical overspray, and improve pharmaceutical tablet efficacy. Large fuel fragments in engines lead to lowered fuel economy and higher pollutant emissions, while small drops yield more agro-spray drift into surrounding residential and environmental zones. Better pharmaceutical tablets will improve drug uptake and patient comfort. Digital inline holography (DIH) provides high resolution, three-dimensional videos with high framing rates (20 kHz). In this experiment, it was used to investigate drop breakup as a function of We. The system measured the 3D fragment positions and sizes that result from drop breakup with fragment velocity determined from positions in adjacent image pairs for each reconstructed hologram using HoloSAND (Guildenbecher, 2015). The DIH system followed that of Guildenbecher et al. (2016) and consisted of a CW laser, spatial filter, and collimator. To capture these videos, a 5 cm diameter laser beam and a high-speed camera were used to record optical information. A Photron SA-Z camera was used to collect the holograms, which contained 3D fragment sizes and positions during breakup. The experimental apparatus included the air jet and drop generator described by (Guildenbecher and Sojka, 2011), and the DIH system. The air jet had a nearly uniform velocity profile, while the drop generator was positioned to release drops of about 3 mm diameter above its centerline. Drop initial height was chosen such that the breakup processes were similar to those for a shock tube (Guildenbecher et al., 2009). Drop We ranged from 30 to 50, controlled by varying the air jet velocity. DIH data were used to create pdf(d,V) showing more than one peak. The peaks are indicative of fragmentation processes that occur due to multiple breakup mechanisms.