Carla Popovici
Research Mentor: Solomon Adera
Mentor Department: MechE, Engineering
Author(s): Carla Popovici, Biruk Teka, Solomon Adera
Session: Session 5 (2:00 PM – 2:50 PM)
Presentation Type: Poster 69
Abstract
Air entrapment during impact has important implications in thermal management via jet impingement cooling. A small air bubble is routinely entrapped when a droplet impacts a textured superhydrophobic surface. In this work, we characterized air entrapment by conducting experiments on well-designed non-wetting (superhydrophobic) and wetting (hydrophilic) surfaces with varying solid fractions. To ensure that Weber number, which scales with the velocity to the second power, does not influence the results, the droplets in this study are released from a set height of 20 cm above the substrate. A high-speed camera is used to capture images at 10000 frames-per-second and MATLAB is used to analyze the time-lapse images. As a result, it was noted that as the solid fraction decreases, inferring more sparse pillars, the entrapped air bubbles become more prevalent. In fact, a central air bubble is rarely visible with denser pillars (a solid fraction >0.3); instead, microbubbles are seen atop and between the pillars. These results illustrate that surface geometry with varying solid fractions play a crucial role in reducing air entrapment during droplet impact. Lastly, as an extension to this investigation, we are currently changing the Weber number by altering the height from where the droplet is released. The insights gained from this work improve the current understanding in the field in regards to air entrapment during droplet impact.
