Portland State University. Department of Mechanical and Materials Engineering
Term of Graduation
Date of Publication
Master of Science (M.S.) in Mechanical Engineering
Mechanical and Materials Engineering
Fluid mechanics -- Research, Reduced gravity environments, Pipettes
1 online resource (xv, 67 pages)
The breakup and rupture of liquid bridges, thin films, bubbles, droplets, rivulets, and jets can produce satellite droplets that are subsequently ejected into their surrounding environment. For example, when any solid object is withdrawn from a liquid bath, the formation of an ever-thinning columnar liquid bridge eventually ruptures along the axis of the bridge. When rupture occurs under typical pipetting conditions the dynamics governing the rupture almost always produce at a minimum a satellite droplet. When these droplets occur they are often too small and too fast to be observed by the human eye. In a terrestrial environment they are of little concern due to the gravitational force imperceptibly returning these droplets back to the bulk fluid. This is not the case for low-g environments where activities such as pipetting creates satellite droplets that are ejected far away from the source fluid creating a risk of contamination within the surrounding working environments. In this work we demonstrate a variety of droplet ejections for the application of pipetting in space and highlight how in a low-g environment such dynamics depend on system geometries, fluid properties, wettability, and withdrawal rate. A drop tower data set is collected in support of a regime map organized by withdrawal Weber and Capillary numbers that highlight when different fluid ejection types are to be expected. Mitigation techniques are presented as a design guide for further applications aboard spacecraft.
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Turner, Caleb Cushman, "Droplet Ejections During Wet Lab Operations Aboard Spacecraft" (2020). Dissertations and Theses. Paper 5549.