Temporal properties of secondary drop breakup in the bag-stamen breakup regime

Abstract

The situation of liquid drop bag-stamen breakup in a continuous air jet flow is investigated by a high speed camera. Test liquids include water, ethanol, and various glycerol mixtures. First, the morphology of bag-stamen breakup is observed and analyzed. The bag-stamen breakup range is found to be in good agreement with the model obtained by Rayleigh-Taylor instability. Then the disk and stamen deformation properties, the fragment average size, and size distribution of ring and stamen are researched in detail, respectively.

Predicting droplet deformation and breakup for moderate Weber numbers

“…At the stages near the sheet breakup (t>4.5ms), both schemes predict increasing deformation in the z-direction (with a slightly better behaviour for the BFW scheme) which contradicts the experimental data. On the other hand, similar trends in increasing deformation were observed in the experimental works of (Cao et al, 2007;Jain et al, 2015;Zhao et al, 2013), while the over-estimation of the crossstream diameter was also present in the detailed simulations of (Jain et al, 2015) for…”

“…care is usually taken in order to minimize the boundary layer of the free jet and obtain A C C E P T E D M A N U S C R I P T 5 a more uniform gas velocity; see selectively (Krzeczkowski, 1980), (Liu and Reitz, 1997), (Lee and Reitz, 2000), (Cao et al, 2007), (Opfer et al, 2012;Opfer et al, 2014), (Flock et al, 2012), (Zhao et al, 2010;Zhao et al, 2013), (Guildenbecher and Sojka, 2011), (Jain et al, 2015) among others. Details for these techniques can be found in (Guildenbecher et al, 2009) among others.…”

“…Later (Zhao et al, 2013) focused on bag-stamen breakup and found that the stamen can be considered as the wave crest of the RT instability, while the growth of stamen was found to have two stages: an initial exponential growth followed by a spike growth. They also measured the size distribution of the fragment droplets, which have been found to follow the log-normal or gamma distribution functions.…”

Secondary breakup of a drop at moderate Weber numbers

“…The increased growth rate of D max for all the regimes is essentially owing to the higher pressure caused by the stagnation of the gas in the bag which results in a radial outward force on the rim [8]. The change in the growth rate of D for different We has been attributed to higher RT instability growth rates corresponding to higher values of drop acceleration, a, with increasing We [56]. Chou & Faeth [8] suggested the following empirical relation for the bag breakup regime, and Zhao et al [56] suggested the following for the bag-stamen breakup mode:…”

“…The change in the growth rate of D for different We has been attributed to higher RT instability growth rates corresponding to higher values of drop acceleration, a, with increasing We [56]. Chou & Faeth [8] suggested the following empirical relation for the bag breakup regime, and Zhao et al [56] suggested the following for the bag-stamen breakup mode:…”