Ryan Jenson

Capillary Driven Flows in Weakly 3 -Dimensional Polygonal Containers

Spontaneous capillary flows in containers of increasing complexity are currently under investigation to determine important transients for low -g propellant management. Significant progress has been made for complex containers that are cylindrical, but many practical systems involve geometries that are tapered. For example, the taper o f an irregular polygonal cross section provides particular design advantages by preferentially locating the liquid where desired and by providing a passive means for fluid phase separation. Passive capillary flow in such containers is termed imbibition and cannot be studied easily on the ground for large, significantly 3 -D geometries. For certain flows the governing equations are known but have not been solved analytically to date due to a lack of experimental data identifying the appropriate boundary condi tions for the flow. The results of drop tower experiments are used in part to support the analysis of imbibition in tapered polygonal sections, and, in particular, a variety of regular n-gonal pyramids. The theory can be used to aid in the design and analy sis of capillary devices such as 3 -D vane networks for bubble -free collection and positioning of fuels for satellites, an important problem concerning propellant and/or cryogenic liquid management aboard spacecraft.

The Capillary Flow Experiments Aboard ISS: Moving Contact Line Experiments and Numerical Analysis

This paper serves as a first presentation of quantitative data reduced from the Capillary Flow Contact Line Experiments recently completed aboard the International Space Station during Expeditions 9-16, 8/2004-11/2007. The simple fluid interface experiments probe the uncertain impact of the boundary condition at the contact line—the region where liquid, gas, and solid meet. This region controls perhaps the most significant static and dynamic characteristics of the large length scale capillary phenomena critical to most multiphase fluids management systems aboard spacecraft. Differences in fluid behavior of nearly identical static interfaces to nearly identical perturbations are attributed primarily to differences in fluid physics in the vicinity of the contact line. Free and pinned contact lines, large and small contact angles, and linear and nonlinear perturbations are tested for a variety of perturbation types (i.e. axial, slosh, and other modes) to right circular cylinders. The video and digitized datasets are to be made publicly available for model benchmarking. In parallel with the experimental effort, blind numerical predictions of the dynamic interface response to the experimentally applied input perturbations are offered as a demonstration of current capabilities to predict such phenomena. The agreement and lack of agreement between the experiments and numerics is our best guide to improve and/or verify current analytical methods to predict such phenomena critical to spacecraft fluid systems design.

Dynamic Fluid Interface Experiments Aboard the International Space Station: Model Benchmarking Dataset

DOI: 10.2514/1.47343 This paper introduces a video database reduced from the handheld capillary flow contact line experiments completed aboard the International Space Station during expeditions 9–16, August 2004–November 2007. The simple fluid interface experiments quantify the uncertain impact of the boundary condition at the contact line: the region where liquid, gas, and solid meet. This region controls many significant static and dynamic characteristics of the large length scale capillary phenomena critical to multiphase fluids management systems aboard spacecraft. Differences in fluid behavior of nearly identical static interfaces to nearly identical perturbations are attributed primarily to differences in fluid physics in the vicinity of the contact line. Free and pinned contact lines, large and small contact angles, and linear and nonlinear perturbations are tested for several manually imparted perturbation types(i.e.,axial,slosh,andothermodes)torightcircularcylinders.Thevideoandsampledigitizeddatasetsaremade publiclyavailableformodelbenchmarking.Asademonstrationoftheutilityofthedatabase,andinparallelwiththe experimental effort, blind numerical predictions of the dynamic interface response to the experimentally applied inputperturbationsareofferedasanexampleofcurrentcapabilitiestopredictsuchphenomena.Theagreementand lack of agreement between the experiments and numerics is a guide to improve or verify current analytical methods to predict such phenomena critical to practical spacecraft fluid systems design.