Capillary Channel Flow (CCF) EU2-02 on the International Space Station (ISS): An Experimental Investigation of Passive Bubble Separations in an Open Capillary Channel

Authors

Mark M. Weislogel, Portland State UniversityFollow
Andrew P. Wollman, Portland State University
Ryan M. Jenson, Portland State UniversityFollow
John T. Geile, Portland State University
John F. Tucker, Portland State University
Brentley M. Wiles, Portland State University
Andy L. Trattner, Portland State University
Claire DeVoe, Portland State University
Lauren M. Sharp, NASA Glenn Research Center
Peter J. Canfield, University of Bremen
Jörg Klatte, University of BremenFollow
Michael E. Dreyer, University of Bremen

Published In

NASA Technical Reports

Document Type

Technical Report

Publication Date

6-2015

Subjects

Fluid mechanics -- Research -- United States

Abstract

It would be signicantly easier to design fluid systems for spacecraft if the fluid phases behaved similarly to those on earth. In this research an open 15:8 degree wedge-sectioned channel is employed to separate bubbles from a two-phase flow in a microgravity environment. The bubbles appear to rise in the channel and coalesce with the free surface in much the same way as would bubbles in a terrestrial environment, only the combined effects of surface tension, wetting, and conduit geometry replace the role of buoyancy. The host liquid is drawn along the channel by a pump and noncondensible gas bubbles are injected into it near the channel vertex at the channel inlet. Control parameters include bubble volume, bubble frequency, liquid volumetric flow rate, and channel length. The asymmetrically confined bubbles are driven in the cross-flow direction by capillary forces until they at least become inscribed within the section or until they come in contact with the free surface, whereupon they usually coalesce and leave the flow. The merging of bubbles enhances, but does not guarantee, the latter. The experiments are performed aboard the International Space Station as a subset of the Capillary Channel Flow experiments. The flight hardware is commanded remotely and continuously from ground stations during the tests and an extensive array of experiments is conducted identifying numerous bubble flow regimes and regime transitions depending on the ratio and magnitude of the gas and liquid volumetric flow rates. The breadth of the publicly available experiments is conveyed herein primarily by narrative and by regime maps, where transitions are approximated by simple expressions immediately useful for the purposes of design and deeper analysis.

Description

This is the final published PDF. This is a government document and no copyright attaches.

Persistent Identifier

http://archives.pdx.edu/ds/psu/16600

Citation Details

Weislogel, M. M., Wollman, A. P., Jenson, R. M., Geile, J. T., Tucker, J. F., Wiles, B. M., ... & Klatte, J. (2015). Capillary Channel Flow (CCF) EU2-02 on the International Space Station (ISS): An Experimental Investigation of Passive Bubble Separations in an Open Capillary Channel.