<p>Secondary
atomization is very important in applications like IC engine and aircraft
engine performance, agricultural sprays, and inkjet printing to name a few. In
case of IC engines and aircraft engines, a good understanding of the modes of
secondary atomization and the resultant drop size can contribute to improving
the fuel injection and hence the efficiency of the engine. Similarly, with the
help of appropriate secondary atomization desired agro-spray quality, ink usage
and print quality can be achieved which would optimize the usage of chemicals
and ink respectively and avoid any harmful effects on the environment.</p>
<p> </p>
<p>One of
the reasons for secondary atomization that occurs very often in most of the
spray applications is the drop impact on a solid or liquid surface. Especially
it is cardinal to understand the impact of a drop on a liquid film since even
in case of impact of liquid drops on a solid surface ultimately the drops that
are injected at a later time are going have a target surface as a thin liquid
film on the solid base due to the accumulation of the previously injected
drops. Analysis of drop impact on a liquid film with non-dimensional thickness
ranging from 0.1 to 1 has been done thoroughly before (Cossali <i>et al.,</i> 2004, Vander Waal <i>et al.,</i>
2006, Moreira <i>et al.,</i> 2010), however,
analysis of drop impact on a liquid film with non-dimensional thickness greater
than 1 is still in a rudimentary stage. This work focuses on determining the
probability density functions for the secondary drop sizes for drops produced
in case of drop impact on a liquid film while varying the h/d ratio beyond 1. The
experimental set-up used to study drop impact includes a droplet generator and
DIH system as mentioned in, Yao <i>et al.</i>
(2017). The DIH set-up includes a CW laser, spatial filter, beam expander and a
collimator as adapted from Guildenbecher <i>et
al.</i> (2016). The height of drop impact is varied to vary the impact <i>We</i>,
by adjusting the syringe height. Three fluids- DI-Water, ethanol and glycerol
are tested for examining the effect of viscosity on the resultant drop sizes. Results
are plotted with respect to viscosity, impact <i>We</i> and the non-dimensional
film thickness, as the fragmentation of drops is directly associated to these
parameters. Results indicate that majority of the secondary droplets lie in the
size range of 25 µm to 50 µm. It is also observed that the tendency of
secondary atomization from crown splashing increases with the increase in <i>We</i>
and decreases with increase in <i>Oh.</i></p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/12543740 |
| Date | 25 June 2020 |
| Creators | Radhika Arvind Bhopatkar (9012413) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/Analysis_of_Droplet_Impact_on_a_Liquid_Pool/12543740 |
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