The Microgravity Research Experiments (MICREX) Database

Principal Investigator(s):

Co-Investigator(s):

Affiliations:

Experiment Origin:

Mission:

LaunchDate/Experiment Date:

Launched From:

Payload Type:

Processing Facility:

Builder of Processing Facility:

Experiment Summary:

This Spacelab D1 experiment was the fifth in a series of investigations designed by Langbein and/or Heide et al. to study the behavior of immiscible systems under low-gravity conditions (see Heide, TEXUS 5, TEXUS 7, TEXUS 8, TEXUS 9). The specific objective of the experiment was to examine the fluid mechanisms operating during the mixing and demixing of binary transparent liquids exhibiting a miscibility gap. Such liquid systems are used as models for metallic alloys whose compounds separate during solidification.

The experiment was performed in a closed liquid container attached to the Spacelab D1 Fluid Physics Module (FPM). The container held two concave, aluminum disks, between which a cylindrical column could be formed. Because the test liquid (benzylbenzoate and paraffin oil) had a low contact angle with aluminum, the disks had sharp edges and were surrounded by teflon rings. The front disk contained a heater redundantly controlled by two thermistors.

During the first part of the experiment procedure, the liquid column was formed by injecting test liquid through a hole in one of the disks and, simultaneously, separating the disks by "...rear plate rotation of the FPM." (4, p. 118) The front disc was then heated and maintained at the desired temperature. The liquid was cooled by passive radiation and conduction.

Although initially only one experimental run had been planned, two experimental runs were performed during the mission.

During Run A, buildup of the liquid column took approximately 10 minutes. The front disk was then heated to approximately 60 ¡C. Reportedly, because of "...liquid mixture spread[ing] across the teflon rings surrounding the supporting metallic disks, the column obtained formed an unduloid rather than a cylinder." (9, p. 325) The 60 ¡C temperature was maintained for approximately 22 minutes. Passive cooling was then allowed to occur. During the first 46 minutes of the experiment, a TV downlink allowed interaction between the Payload Specialist and ground. For approximately 10 minutes after the TV downlink was halted, a Vinten camera recorded the behavior of the liquid column. The recording was then halted until the liquid was sucked back into the reservoir.

Because of the "successful" performance of the first experimental run, a second experiment (Run B) was performed. The procedure was the same as Run A except that (1) the heater temperature was increased to 75 o C (to increase the Marangoni velocity and distinguish between reproducible and irreproducible phenomena) and (2) "...only the last seconds of the heating phase, the cooling phase and the recovery of the column [were] recorded." (9, p. 326)

The conclusions from both experimental runs were reported as follows:

(1) The mechanisms of capillarity, stability, and spreading are significant during the mixing and demixing of fluids exhibiting a miscibility gap. These mechanisms control the final distribution of the two components.

(2) Marangoni convection caused by non-uniform heating and cooling was lower than expected. The convection differed by at least one order of magnitude from that determined by ground experiments. This difference was attributed to (a) contamination of the liquid mixture from long periods of storage and/or (b) "...contrasting effects of temperature and concentration on the surface tension due to the component having the lower surface tension (paraffin oil) getting enriched on the cold side." (9, p. 327) If the difference in Marangoni convection can be ascribed to (b), "...the advantage of a free fluid surface, the suppression of heterogeneous nucleation, will not generally be balanced by the disadvantage of stronger Marangoni convection. In that case containerless processing appears commendable also for metallic alloys." (9, p. 327)

(3) Slow cooling reduced the demixing of the two liquids, suggesting this result may also be true for metallic alloys.

(4) The diffuse interface layer between the two liquids that mixed exhibited properties of normal interfaces (e.g., capillarity, stability, spreading effects and Marangoni convection).

Key Words:

Number of Samples:

Sample Materials:

Container Materials:

Experiment/Material Applications:

References/Applicable Publications:

(2) Langbein, D. and Heide, W.: Mischen und Entmischen transparenter Flussigkeiten. In BMFT/DFVLR Scientific Results of the German Spacelab Mission D1, Abstracts of the D1- Symposium, Norderney, Germany, August 27-29, 1986, pp. 81-84. (in German)

(3) Langbein, D.: Mixing and Demixing of Transparent Liquids. In Scientific Goals of the German Spacelab Mission D1, WPF, 1985, pp. 139-140. (preflight)

(4) Langbein, D. and Heide, W.: Mixing and Demixing of Transparent Liquids Under Microgravity. In 6th European Symposium on Material Sciences Under Microgravity Conditions, Bordeaux, France, December 2-5, 1986, ESA SP-256, pp. 117-123.

(5) Gonfalone, A.: The Fluid Physics Module- A Technical Description. In ESA 5th European Symposium on Materials Sciences Under Microgravity, Results of Spacelab 1, Schloss Elmau, November 5-7, 1984, ESA SP-222, pp. 3-7. (status post-Spacelab 1, prior to D1)

(6) Ceronetti, G.: The Fluid Physics Module Design. XXV Rassegna Internazionale Elettronica Nucleare Ed Aerospaziale. Roma, March 10-19, 1978, pp. 76-83. (prior to Spacelab 1)

(7) Martinez, I., Haynes, J. M., and Langbein, D.: Fluid Statics and Capillarity. In Fluid Sciences and Materials Science in Space, Edited by H. U. Walter, Springer Verlag, 1987, pp. 53-80. (related topics)

(8) Langbein, D.: Fluid Physics. In Proceedings of the Norderney Symposium on Scientific Results of the German Spacelab Mission D1, Norderney, Germany, August 27-29, 1986. (specifically pp. 101-102; post-flight)

(9) Langbein, D. and Heide, W.: Mixing and Separation in Transparent Liquids Under Microgravity. In Proceedings of the Norderney Symposium in Scientific Results of the German Spacelab Mission D1, Norderney, Germany, August 27-29, 1986, pp. 321-327. (post-flight)

(10) Input received from Principal Investigator D. Langbein, August 1993.

Contact(s):