« Go Back

Research Containing: Boundary condition

The capillary flow experiments aboard the International Space Station: Status

by on 9 June 2015in Physical Sciences No comment

This paper provides a current overview of the in-flight operations and experimental results of the capillary flow experiment (CFE) performed aboard the International Space Station (ISS) beginning August 2004 to present, with at least 16 operations to date by five astronauts. CFE consists of six approximately 1–2 kg experiment units designed to probe certain capillary phenomena of fundamental and applied importance, such as capillary flow in complex containers, critical wetting in discontinuous structures, and large length scale contact line dynamics. Highly quantitative video images from the simply performed experiments provide direct confirmation of the usefulness of current analytical design tools as well as provide guidance to the development of new ones. A description of the experiments, crew procedures, performances and status of the data collection and reduction is provided for the project. The specific experimental objectives are briefly introduced by way of the crew procedures and a sample of the verified theoretical predictions of the fluid behavior is provided. The potential impact of the flight experiments on the design of spacecraft fluid systems is discussed in passing.

Related URLs:
http://www.sciencedirect.com/science/article/pii/S0094576509001386

Preliminary Results from the Capillary Flow Experiment Aboard ISS: The Moving Contact Line Boundary Condition

by on 9 June 2015in Physical Sciences No comment

The Capillary Flow Experiment (CFE) consists of six approximately 2kg test vessels constructed by NASA to probe certain capillary phenomena of fundamental and applied importance. The light weight, low-volume hardware can be shipped to orbit on short notice as cargo space permits and the experiment performed in stand-alone mode by a single crewmember on, for example, the Maintenance Work Area (workbench) of the International Space Station. Video images from the simply performed crew procedures provide highly quantitative data for the confirmation of current analytical design tools as well as directions for further theoretical development. This paper presents a narrative of preliminary results from the first Capillary Flow Experiment (CFE) conducted aboard ISS in August-September 2004. The tests are performed as per of NASA’s Saturday Morning Science Program on ISS and completed in good order by Astronaut Michael Fincke who collected approximately 100 data sets that compare large length scale capillary surface oscillations and damping for two otherwise identical cylindrical tanks differing only in respect to a critical yet uncertain boundary condition at the contact line. Linear, nonlinear, and destabilizing slosh, swirl, axial, and other disturbances are studied. The large data set is being reduced for comparisons to the blind predication of a group of numerical analysis assembled to gauge the accuracy of present methods to predict large length scale capillary dynamics critical to fluids management in spacecraft (i.e. fuels, cryogens, water). The success of the experiment reported herein serves as a testimony to astronaut ingenuity and the perhaps surprisingly flexible fluids laboratory of the ISS for safe and simple fluids experimentation.

Related URLs:

Interim Results from the Capillary Flow Experiment Aboard ISS: The Moving Contact Line Boundary Condition

by on 9 June 2015in Physical Sciences No comment

This paper highlight the in-flight operations of the Capillary Flow Experiment Contact Line experiments (2 each) performed aboard the International Space Station (ISS) during the period between Increment 9 ad 13 (8/2004-9/2006). The CFE-CL vessels are simple fluid interface experiments that 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 fluid management systems aboard spacecraft. Difference in fluid behavior of nearly identical statics interfaces to nearly identical disturbances are attributed to differences in fluid physics in the vicinity of the contact line. The CFE-CL experiments are conducted on five occasions by ISS Astronauts M. Fincke, W. McArthur, and J. Williams. The number of tests performed including additional science experiments is made possible by various centrifuge techniques employed by the astronauts permitting the re-use of the once-wetted container. Several of these ‘extra science’ experiments are briefly described herein. Intermittent real-time video and audio downlink, continuous communication with the ground crews at NASA JSC, MSGFC and GRC, and the clear and entreating commentary of the crew made the conduct of the tests on ISS an enjoyable, laboratory-like experience for the science on the ground. The flight tapes from the onboard cameras have been results to Earth (name flight) and are expected to be digitized, reduced and made publically available in the near future. A concurrent blind numerical analysis is underway to predict the experiments result using a generally accepted CFD-tool with specific contact line boundary conditions.

Related URLs:
http://dx.doi.org/10.2514/6.2007-747

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

by on 9 June 2015in Physical Sciences No comment

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 perturba- tion types (i.e. axial, slosh, and other modes) to right circular cylinders. The video and digi- tized 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 capa- bilities 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.

Related URLs:
http://dx.doi.org/10.2514/6.2008-816

Postflight summary of the Capillary Flow Experiments aboard the International Space Station

by on 9 June 2015in Physical Sciences No comment

This paper provides a summary of the experimental, analytical, and numerical results of the Capillary Flow Experiment (CFE) performed onboard the International Space Station (ISS) from Increment 9 (beginning August, 2004) through Increment 16 (ending December, 2007), with 19 operations by 7 astronauts; M. Fincke, W. McGarthur, J. Williams, S. Williams, M. Lopez-Alegria, C. Anderson, and P. Whitson. CFE consists of 6 approximately 1 to 2kg experiment units designed to probe certain capillary phenomena of fundamental and applied importance, such as capillary flow in complex containers, critical wetting in discontinuous structures, and large length scale contact line dynamics. Highly quantitative video images from the simply performed flight experiments provide immediate confirmation of the usefulness of current analytical design tools as well as provide guidance to the development of new ones. A brief review of the experiments and procedures is provided before reporting the status of the data collection, reduction, and comparisons with both analytic and numerical predictions. The products of the work include design tools for modeling capillary interface dynamics relevant to spacecraft engineering systems. The CFE experimental program was initiated in February 2003 as part of a fast-paced unscheduled payloads/experiments program. All six of the units were performed on standby or at times as part of NASA Saturday Science and all units have been returned to Earth for post flight analysis. The experiments were conducted in stand-alone mode by a single crewmember on the Maintenance Work Area of the ISS.

Related URLs:

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

by on 9 June 2015in Physical Sciences No comment

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. Difference in fluid behavior of nearly identical static interfaces to nearly identical perturbations are attributed primarily to difference 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 and other modes) to right circular cylinders. The video and sample digitized datasets are made publically available for model benchmarking. As a demonstration of the utility of the database, and in parallel with the experiment effort, blind numerical predication of the dynamic interface response to the experimentally applied input perturbation are offered as an example of current capabilities to predict such phenomena. The agreement and lack of agreement between the experiment and numeric is a guide to improve or verify current analytical methods to predict such phenomena critical to practical spacecraft fluid systems design.

Related URLs:
http://dx.doi.org/10.2514/1.47343