Analysis Of Ferrofluids Exposed To Magnetic Fields In Micro-gravity

Paper number

IAC-07-A2.2.07

Author

Mrs. Ulrike Endesfelder, University of Bonn, Germany

Coauthor

Coauthor

Elisabeth Krause, University of Bonn, Germany

Coauthor

Alice Verweyen, University of Bonn, Germany

Coauthor

Anne Angsmann, University of Bonn, Germany

Coauthor

Sebastian Bürgel, University of Zurich, Switzerland, Switzerland

Year

2007

Abstract

Within the scope of the 8th ESA Student Parabolic Flight Campaign we performed an experiment about the behaviour of ferrofluids. 
A ferrofluid is a solution of magnetic particles in a colloidal suspension whose flow can be controlled by magnetic fields.
The unique properties of a ferrofluid – a stable liquid that responds to magnetic attraction – make it useful in devices where fluid properties and resistance to gravity are needed, such as rotary seals in disk drives for computers, dampers for audio speakers and many more.

The experiment consists of a ferrofluid which is placed in the homogenous magnetic field of a pair of magnetic coils and is observed with two video cameras to later construct 3-D models. The experiment rest frame is kept at a constant orientation in space by a guiding system based on an ESP-sensor. The external magnetic field is varied and the resulting motion of the ferrofluid is recorded.

On earth, the reaction of a ferrofluid to a magnetic field is constrained by gravity, as the gravitational force confines the flow and influences especially the condition of stability and therefore the shape of the ferrofluid. 

In a force free environment, we exposed the ferrofluid to precisely known magnetic fields of different strengths and time-dependence. With the two synchronised videotapes the three-dimensional motion of the ferrofluid is reconstructed. The results are compared to those of the same experiment carried out on earth.

To gain real force free environment a special guiding system is needed.
During every parabola, the airplane rotates around the axis leading through its wings. Thus also the experiment setup inside the plane rotates in space causing shear forces on the ferrofluid. To observe the free motion of the ferrofluid, it is essential to switch off these distortions. Therefore an Electronic Stability Program (ESP, usually placed in cars) provided by Bosch is used, which measures the angular velocity of the aircraft’s rotation. This output signal controls the tracking of the setup. By rotating contrary, the experiment is stabilised in space.

The analysis shows that the theoretical investigations about ferrofluids make correct predictions about the influence of gravity for the motion and shape of a ferrofluid. 
As a main technical result we can recommend our stabilising system to other groups with acceleration susceptible experiments. The ESP-sensor provides an easy and sensitive method to implement position control.

Abstract document

IAC-07-A2.2.07.pdf

Manuscript document

IAC-07-A2.2.07.pdf (🔒 authorized access only).

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