June 2013 – The second set of Interior Corner Flow (ICF) vessels (ICF3, ICF5, ICF6, ICF7, and ICF8) were launched on board the ATV-4 on June 5, 2013. Operations on board the ISS are continuing for the first set on CFE-2 vessels ICF4 and ICF9.
November 2012 – The first set of ICF vessels (ICF4
and ICF9) were launched on SpaceX-1 on October 7, 2012,
then transferred to the ISS. The next set of five
ICF vessels (ICF3, ICF5, ICF6, ICF7 and ICF8) are currently
going through environmental testing on the ground in preparation
for flight and are scheduled to launch on ATV-4 in April
October 2012 – The next set of ICF
vessels (ICF4 and ICF9) are tentatively scheduled to launch
on SpaceX-1. Five additional ICF vessels (ICF3, ICF5,
ICF6, ICF7, and ICF8) are tentatively scheduled to launch on
SpaceX-2 at the end of 2012. Each ICF vessel is uniquely
designed to explore the effect of the vessel geometry on interior
corner wetting in microgravity.
May to June 2012 – The final two scheduled
Vane Gap 2 (VG2) unfilled perforations tests were completed. Don
Pettit completed a test on May 10, 2012, and Joe Acaba
completed the second test on June 13, 2012. Both
Don and Joe were able to find all four critical wetting
angles. All scheduled unfilled perforation tests
have been completed for VG2.
May 2012 – Astronaut crew training was
held for Capillary Flow Experiments 2 (CFE-2) flight
experiments on April 30 and May 1 at NASA JSC. Astronauts
Chris Cassidy (Increments 35-36) and Karen Nyberg (Increments
36-37) were trained with the CFE-2 ICF4 and ICF9 trainer
units, including installation on a Maintenance Work
Area (MWA) in a mockup of the ISS LAB module. CFE-2
training was performed by Chuck Bunnell (ZIN). The
CFE-2 PI, Mark Weislogel attended and provided
a science overview for the CFE-2 experiment.
March 29, 2012 – A Systems Acceptance
Review (SAR-1) was held for ICF4 and ICF9 to verify
the hardware is ready for flight. The ICF4
and ICF9 hardware passed the SAR-1 review and are
being prepared for flight on SpaceX-1.
January to March 2012 – Increment
30 commander, Dan Burbank, and flight engineer,
Don Pettit, completed a series of vane gap tests
with filled (VG1) and unfilled (VG2) vane perforations
to determine critical wetting angles. An extra science test was also
completed using the ICF1 vessel. All test
matrices and extra science runs have been completed
for VG1 and ICF1.
January 26, 2012 – Astronauts Sunita
Williams, Tom Marshburn, and Kevin Ford were trained
on installation of CFE-2 units on the Maintenance Work
Area (MWA) and CFE-2 science operations. Oct. 7,
2011 – Increment 29 commander, Mike Fossum
performed a Filled Perforations test of VG1 investigating
the critical angles in quadrants 3 and 4. Observed
the same bulk shift phenomena initially observed
during the Sept. 15 test.
Sept. 30, 2011 – Increment 29 commander,
Mike Fossum performed the VG2 initial “Dry Chamber” test
and found the expected critical angles within 3-4
deg of predictions.
Sept 15, 2011 – Increment 28 flight
engineer, Mike Fossum performed the first Filled Perforations
test of VG1 investigating the critical angles in quadrants
1 and 2. Observed a bulk shift phenomena,
i.e. movement of fluid from one side of vane to
the other at base of test chamber.
May 3, 2011 – The ISS flight engineer
Ron Garan operated the CFE-2 Interior Corner Flow2
(ICF2) vessel in the US Lab on the Maintenance
Work Area (MWA). The test operation consisted
of two compressed bubble tests in the transport
tube of the ICF2 vessel. The Principal Investigator,
Mark Weislogel was at the NASA Glenn Research Center
to observe and direct operations from the Telescience
January 18, 2011 – Cady Coleman
completed 3 test runs on the CFE-2 Interior Corner
Flow2 (ICF2). This
series of tests were performed with ICF2 to test
capillary flow with bubbles in the test fluid.
December 2010 - Capillary Flow Experiment-2
(CFE) Vane Gap-1 operated on ISS. The CFE
Van Gap-1 (VG-1) module was operated for a fourth
time by Increment 25 astronaut Scott Kelly on Wednesday,
December 8, 2010.
September 29, 2010 – The
CFE-2 experiment launched 4 test vessels on STS-131/Flight
19A in April 2010. On September 7, 2010 the CFE-2
experiment was set up in the Japanese Experiment
Module and operated by crewmember Shannon Walker.
To date CFE-2 has completed 11 of 16 Interior Corner
Flow 1 (ICF1) test points.
Capillary Flow Experiment - NASA astronaut
Scott Kelly, Expedition 26 commander, works on the hardware
setup for a Capillary Flow Experiment (CFE) Vane Gap-1
experiment. The CFE is positioned on the Maintenance
Work Area in the Destiny laboratory of the International
Space Station. CFE observes the flow of fluid, in particular
capillary phenomena, in microgravity.
Astronaut Don Petit demonstrates how
to use a cup he made from a piece of transparency paper.
The unique shape allows him to drink his coffee in zero
gravity without having to suck it from a bag.
Flow Experiments (CFE-2) consists of eleven approximately
1 to 2 kg test vessels designed to probe certain capillary
phenomena of fundamental and applied importance, such as:
capillary flow in complex containers, critical wetting
in discontinuous structures and surfaces, and passive gas-liquid
phase separations. Quantitative video images from the simply-performed
flight experiment crew procedures will provide immediate
confirmation of the usefulness of current analytical design
tools, as well as provide guidance to the development of
• Vane Gap experiments investigate a fundamental, geometric critical wetting
condition that occurs in complex systems where one or more substrates are porous
(i.e. screens or perforated plates). The experiments determine both dynamic
wetting and equilibrium interface behavior.
• Interior Corner Flow experiment quantifies the nature of large length
scale capillary flows and bubbly capillary flows throughout 3-dimensional polygonal
containers for the purpose of theory development, verification, a demonstration
of passive phase separation.
Capillary Flow Experiments (CFE)
The Capillary Flow
Experiments (CFE) are a suite of fluid physics flight experiments
designed to investigate large length scale capillary flows
and phenomena in low gravity. The CFE data to be obtained
will be crucial to the Space Exploration Initiative, particularly
as it pertains to fluids management systems such as fuels
and cryogen storage systems, water collection and recycling,
thermal control systems, and materials processing in the
liquid state. NASA’s current plans for exploration
missions assume the use of larger liquid propellant masses
than have ever flown on interplanetary missions. Under
low-gravity conditions, capillary forces can be exploited
to control fluid orientation so that such large mission-critical
systems perform more reliably.
CFE Experiment Video
CFE is a simple fundamental
scientific study that can yield quantitative results from
safe, low-cost, short time-to-flight, handheld fluids experiments.
The experiments aim to provide results of critical interest
to the capillary flow community that cannot be achieved
in ground-based tests such as tests to probe dynamic effects
associated with a movingcontact boundary condition, capillary-driven
flows in interior corner networks, and critical wetting
phenomena in complex geometries. Specific applications
of the results center on particular fluids challenges concerning
propellant tanks. The knowledge gained will help spacecraft
fluid systems designers increase system reliability, decrease
system mass, and reduce overall system complexity.
CFE encompasses three experiments with two unique experimental
units per experiment. There are multiple tests per experiment.
Each of the experiments employs parametric ranges and test
cell dimensions that cannot be achieved in groundbased experiments.
All units use similar fluid injection hardware, have simple
and similarly sized test chambers, and rely solely on video
for highly quantitative data. Silicone oil will be used for
these tests. Differences between units are primarily fluid
properties, wetting conditions, and test cell geometry. The
experiment procedures are simple and intuitive.
Spontaneous capillary flows in containers of increasing complexity
have been designed 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 containers with geometries that
The taper of the irregular polygonal cross section of the
test cells provides particular design advantages in preferentially
locating the liquid where desired. Passive capillary flow
in such containers is called imbibition and cannot be tested
on the ground for large three-dimensional geometries with “underdamped
fluids”—a most common characteristic of low-g
fluids systems. The equations governing the process are known
but have not been solved analytically to date because of
a lack of experimental data identifying the appropriate boundary
conditions for the flow problem. Experimental results will
guide the analysis by providing the necessary boundary condition(s)
as a function of container cross section and fill fraction.
The benchmarked theory can then be used to design and analyze
capillary devices such as three-dimensional vane networks
and tapered screen galleries for bubble-free collection and
positioning of fuels for satellites, an important and outstanding
problem for propellant management aboard spacecraft.
A complicated critical wetting condition arises between interior
corners that do not actually contact; such as in the gap
formed by a vane and tank wall of a large propellant storage
tank (a commonality in practice), or near the intersection
of vanes in a tank with complex vane network. Two CFE units
will be employed to investigate this phenomenon using a right
cylinder with elliptic cross section with a single central
vane that does not contact the container walls.
The vane can be pivoted varying the angle between the vane
and the wall and also varying the size of the vane-wall gap.
The vane is slightly asymmetric so that two gaps can be tested
for each container. All static interface shapes recorded
by video will be compared quantitatively with shapes computed
using a computer algorithm. A major goal of this experiment
is to carefully observe all interface configurations during
the rotation of the vane and to test the repeatability and
reversibility of the critical wetting phenomena.
Two CFE units will be used to study a fundamental and practical
concern for low-g fluid phenomena—the impact of the
dynamic contact line. The contact line controls the interface
shape, stability, and dynamics of capillary systems in low
g. The CFE–CL experiments will provide a direct measure
of the extremes in behavior expected from an assumption of
either the free or pinned contact line condition. The two
units are identical except for their respective wetting characteristics.
The CL–1, the ICF, and VG units are complete and awaiting
launch. CFE–CL unit 2 (CL–2) was launched to
the International Space Station (ISS) on Progress 13 in January
2004. ISS Science Officer Michael Fincke, operated the CL–2
unit on August 28 and again on September 18, 2004. CL–2
operations were also performed on December 20, 2005 and on
April 18, 2006 by ISS Science Officers, William McArthur
and Jeff Williams, respectively. Video data was taken and
is currently being analyzed. Tests include a variety of fluid
disturbances, such as tap, slide, multiple slide, push, swirl,
and axial perturbations.
Preliminary results were recently reported1 where it has
been observed that the correct contact line boundary condition
is pivotal to accurate modeling of large length scale capillary
surface dynamics. In addition, it was observed how large
amplitude multiple slide disturbances act to form ‘hourglass’ configurations
in the smooth cylinder while the surface remains pinned in
the pinning cylinder. Axial mode drop ejection tests were
performed and obvious differences in settling time and natural
frequency as a function of contact line condition and disturbance
type were observed. Publication of the quantified data awaits
further analysis of the data.