Project

Abstract

    The objective of the Surface Tension Impelled Low-gravity Liquid Mixing (STILLMix) experiment is to gather visual data on the boundary interactions and mixing of two liquids brought into contact by allowing them to wet the same surface in microgravity conditions.

    The proposed approach and the results obtained from such experiments will be unique for microgravity because of the dominance of surface tension effects over gravitational forces. In a terrestrial environment, gravity would force the liquid down, spreading the sample across the test section with more force than the surface tension alone would impart.

    We propose to study and demonstrate whether mixing can be accomplished with surface tension as the only driving force. A series of grooves will be machined into the test surfaces in order to shape the liquids' wavefronts for optimal mixing upon contact. Our experiment will yield better insight into the nature of surface tension driven mixing as well as the mechanisms of mixing dependent upon properties of the two liquids, the solid surface, and the surface structure. The optimal surface structure pattern will be determined by a series of preliminary experiments run in terrestrial conditions. A control series of experiments, with a smooth mixing surface, but otherwise identical, will be run alongside for comparison. The mixing process will be recorded with a digital video camera; the images will be analyzed using digital image processing tools to ascertain the nature of mixing and the shape of the wavefronts.

    Applications for the mixing of fluids in microgravity conditions include a variety of chemistry and biology experiments, process engineering, and waste recycling on the Shuttle and ISS. Currently, mixing of two fluids or a fluid and a solid is generally accomplished through mechanical means to ensure homogeneity. Although mechanical mixing is fast, it consumes valuable power. In spacecraft applications, passive mixing is preferred, as it would save power and improve system reliability. This also reduces weight and decreases mission cost.

Downloads

    Our final report to NASA updates the actual procedure followed compared to that in the TEDP (the best laid plans...) and also discusses our data, get it now in Acrobat format.

    Download a presentation outlining our project, proposal and the NASA program. It's available in both Acrobat and PowerPoint formats.

    Also available is a media packet, intended to be a quick but through introduction to our project. It is available in Acrobat and Word formats.

    Our Updated TEDP (Test Equipment Data Package) is also available for download. It contains detailed information about our project. It's available in both Acrobat and Word formats.

    If you're just interested in the refinements to the TEDP that were added from the original submission, it's also available, in Acrobat and Word formats.