Actions for Enhanced Damping for Capillary Bridge Oscillation Using Velocity Feedback

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Enhanced Damping for Capillary Bridge Oscillation Using Velocity Feedback

Author
Wei, Wei
Published
August 2004.
Physical Description
1 electronic document
Additional Creators
Thiessen, David B. and Marston, Philip L.
Online Version

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Unclassified, Unlimited, Publicly available.
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Summary
The stability of cylindrical liquid bridges in reduced gravity is affected by ambient vibrations of the spacecraft. Such vibrations are expected to excite capillary modes of the bridge. The lowest-order unstable mode is particularly susceptible to vibration as the length of the bridge approaches the stability limit. This low-order mode is known as the (2,0) mode and is an axisymmetric varicose mode of one wavelength in the axial direction. In this work, an optical system is used to detect the (2,0)-mode amplitude. The derivative of the error signal produced by this detector is used to produce the appropriate voltages on a pair of ring electrodes which are concentric with the bridge. A mode-coupled Maxwell stress profile is thus generated in proportional to the modal velocity. Depending on the sign of the gain, the damping of the capillary oscillation can be either increased or decreased. This effect has been demonstrated in Plateau-tank experiments. Increasing the damping of the capillary modes on free liquid surfaces in space could be beneficial for containerless processing and other novel technologies.
Other Subject(s)
Collection
NASA Technical Reports Server (NTRS) Collection.
Note
Document ID: 20040161213.
Strategic Research to Enable NASA's Exploration Missions Conference and Workshop: Poster Session, Volume 2; 503-508; NASA/CP-2004-213205/VOL2.
Terms of Use and Reproduction
No Copyright.
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