Capillary Channel Flow (CCF) Fluid Physics
Research Area: Fluid Physics
Expedition(s): 25-ongoing
Principal Investigator(s): ● Michael Dreyer, PhD, University of Bremen, Bremen, Germany
RESEARCH OBJECTIVES
Data from the Capillary Channel Flow (CCF) experiment will help to innovate solutions to
transporting liquids (such as fuels, low temperature liquids like liquid nitrogen and water) in
microgravity. By understanding capillary fluid flow rates in microgravity, hardware can be
developed for “pumping” liquids from one reservoir to another without the need for a pump
with moving parts. The reduced cost, weight, and improved reliability of such equipment make
this a particularly attractive technology for NASA.
EARTH BENEFITS
Technologies for liquid management in space use capillary forces to position and transport
liquids, since the hydrostatic pressure is absent which gives the liquid a defined surface and
enables easy withdrawal from the tank bottom. But the effect of capillary forces is limited on
Earth to a few millimeters. In space these forces
affect free surfaces that extend over meters.
For the application of open channels in
propellant tanks of spacecraft, design
knowledge of these limitations are a
requirement, predicated with a bubble free
liquid restriction prior to entering the thrusters.
SPACE BENEFITS
CCF will significantly reduce cost and weight,
while improving reliability of spacecraft tank
designs that can supply gas-free propellant to
spacecraft thrusters using capillary vanes.
Technologies for liquid management in space use capillary forces to position and transport
liquids, since the hydrostatic pressure is absent that gives the liquid a defined surface and
enables easy withdrawal from the tank bottom. But the effect of capillary forces is limited on
Earth to a few millimeters. In space these forces affect free surfaces that extend over meters.
For the application of open channels in propellant tanks of spacecraft, design knowledge of
these limitations are a requirement, predicated with a bubble-free liquid restriction prior to
entering the thrusters.
RESULTS
CCF investigates forced liquid flow through partially open capillary channels aboard the
International Space Station (ISS). The flow channel is made up of either two parallel plates or an
open wedge conduit. Results collected show favorable agreement with predictions of critical
flow rates and bubble separation rates. The results also indicate the nature of desabilizations
and the myriad outcomes of gas liquid flows in the microgravity environment. Regarding critical
ISS040E088856 - NASA astronaut Reid Wiseman
installs CCF hardware in the Microgravity Science
Glovebox (MSG).