The objective of this Skylab demonstration was to study the dynamic behavior of a column of liquid suspended between two aluminum discs. Such columns of liquid (better known as liquid bridges) are used to model the containerless float zone solidification geometry.
During the third manned Skylab mission, the make-shift liquid bridge apparatus was constructed using onboard equipment. Two socket wrench extension rods were configured in parallel such that a small gap existed between the two rods. At the ends of the rods forming the gap, circular aluminum discs were attached. "The front surfaces of the discs were coated with grey tape which had been previously treated by immersion in acetone so as to reduce the contact angle with water. During the course of the experiments, the outer edges of the discs were coated with Krytox oil to prevent capillary wetting of water in that region." (1, p. 843). The rods were mounted in camera mounts such that the assembly was free to rotate smoothly.
"Rotation of the zones was performed manually by first winding ... twine around the socket wrench and then withdrawing it at a uniform rate." (1, p. 843) Liquid bridges were created by (1) deploying a volume of fluid from a syringe on to each aluminum disc, (2) moving the discs close together to create one liquid volume, and (3) separating the discs to suspend the liquid into the desired column length. During 26 separate zone investigations, several water-based bridges were successfully formed, as bridge length, rotational direction, and bridge fluid were varied. Fluid additives such as rope particles aided internal fluid motion observance, while liquid soap was used to vary surface tension and viscosity. Video taping of most of these investigations was successfully achieved. Among the several observations of interest was the creation of a long, static, stable, unduloid bridge which exceeded the theoretical length limit for a right circular cylinder. When the liquid bridge was subjected to "...longitudinal vibrations of the end discs....standing waves occurred when the disc oscillation frequency coincided with a resonant frequency of the surface.
"When standing waves were produced, there was no transfer of liquid from one wave region to another inside the zone." (1, pp. 847-848) Rotation of the zone also resulted in some interesting observations. "For sequences involving the single rotation of only one bounding disc, the zone assumed an axisymmetric bottle shaped deformation possessing stability limits in general agreement with theory. For sequences involving equal rotation rates of both bounding discs, the zone becomes deformed in a non-axisymmetric fashion resembling a turning skipping rope [or C-mode] when the zone lengths exceed some value in the vicinity of...[(2/3)(pi)R]. Short zone lengths do not generally develop the rotating C-mode but do demonstrate capillary wave resonances presumably arising from nonparallel disc alignment." (2, p. 6)
(2) Carruthers, J. R., Gibson, E. G., Klett, M. G., and Facemire, B.: Studies of Rotating Liquid Floating Zones on Skylab IV. American Institute of Aeronautics and Astronautics, 10th Thermophysics Conference, Denver, Colorado, May 27-29, 1975, AIAA Paper #75-692, 8 pp.
(3) Chassay, R. P. and Schwaniger, A.: Low G Measurements at NASA. In Workshop Proceedings of the Measurement and Characterization of the Acceleration Environment on Board the Space Station, August 11-14, 1986, Guntersville, Alabama, p. 9-1. (acceleration measurements)
(4) TV101-Liquid Floating Zone. In MSFC Skylab Corollary Experiment Systems Mission Evaluation, NASA TM X-64820, September 1974, pp. 7-4 - 7-10. (post-flight)
(5) Naumann, R. J. and Herring, H. W.: Experiment TV101, Liquid Floating Zone. In Materials and Processing in Space: Early Experiments, NASA SP-443, 1980, pp. 79-81. (post-flight)
(6) Bannister, T. C.: Science Demonstrations on Skylab in the Material Processing Area. In Proceedings of the Third Space Processing Symposium on Skylab Results, April 30-May 1, 1974, Marshall Space Flight Center, Huntsville, Alabama, Vol. 1, June 1974, pp. 491-505. (post-flight)
(7) Bannister, T. C.: Skylab III and IV Science Demonstrations. NASA TM X-64835, March 1974, pp. 6-8. (post-flight)
(8) Naumann, R. J. and Mason, E. D.: Liquid Floating Zone. In Summaries of Early Materials Processing in Space Experiments, NASA TM-78240, August 1979, pp. 40-41. (post-flight)
(9) Liquid Floating Zone (SD20-TV101). In MSFC Skylab Mission Report-Saturn Workshop, NASA TM X-64814, October 1974, pp. 12-89 - 12-90.
(10) Input received from Principal Investigator John Carruthers, June 1993.