Microgravity Research Opportunities for the 1990s (1995) / Chapter Skim
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Microgravity Research Opportunities for the 1990s: Chapter 3
Microgravity Research Opportunities for the 1990s: Chapter 3
Pages 53-61
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From page 53... ...
CHAPTER 5 The fluid mechanics and transport phenomena area of the microgravity research CHAPTER 6 program should have both fundamental and applied objectives: CHAPTER 7 PART III Fundamental problems. A key objective for fundamentally oriented CHAPTER 8 research should be the identification and description of new phenomena that may APPENDIX A influence transport and other applications in microgravity due to the change in APPENDIX B parameter range from the ground-based norm.1 A second general objective for fundamental research should be to focus on problems in which a low-gravity environment can contribute to the fundamental understanding of observed phenomena by providing a unique experimental window.
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From page 54... ...
Five of those concerned the effects of capillarity on fluids: isothermal meniscus between two plates of unequal radii; free surface oscillations in drops; liquid-column stability with rotation, vibration, and stretching; axisymmetric free surface behavior due to forced disturbances in partly filled containers; and kinetics of the spreading of a tethered drop. The sixth experiment was designed to study thermocapillary flows in a liquid bridge.
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From page 55... ...
The STDCE6-14 conducted in an interactive mode on the USML-1 mission was the first thermocapillary flow experiment with state-of-the-art diagnostic techniques to yield quantitative flow field and temperature data over a wide range of conditions with two different heating modes and various initial interface shapes, which are unique to the microgravity environment. The nature and extent of large Marangoni number steady thermocapillary flows in a cylindrical chamber were determined.
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From page 56... ...
The effects of flow phenomena driven by surface tension forces are frequently masked by competing gravitational forces in the terrestrial environment but become significant or dominant in reduced gravity. This provides an opportunity for a unique experimental window that can be used to study surface tension-driven convection phenomena, as well as the microscale physics of the interfacial zone (e.g., surface or interfacial rheology in systems with surfactants or the dynamics of the contact line on a solid boundary)
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From page 57... ...
One example that has received significant study already is the dynamics of individual bubbles or drops in acoustic fields. Technology Development One of NASA's missions is to "provide technology for present and future civil space missions and provide a base of research and technology capabilities to serve all National space goals."16 Many of the technologies required for NASA programs involve transport phenomena, including power systems; thermal management systems; spacecraft fire hazard management; cryogenic engines; fluid systems tankage; physical and chemical life-support systems; and user support subsystems such as refrigerators.
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From page 58... ...
The committee believes that the following topics, in addition to being of intrinsic scientific interest, are critical to provide the knowledge base required to design effective and reliable space-based systems and facilities in which fluid processes are involved: Convective processes at low Reynolds number. Buoyancy affects the transport of heat and mass when the Reynolds number becomes small enough in the terrestrial flow of fluids with density variations.
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From page 59... ...
Among the topics that this program should cover are surface tension-driven flows and capillary effects; multiphase heat transfer and fluid flows; and the behavior of complex fluids such as colloids, granular media, and foams, whose dynamical behavior can be strongly influenced by gravity. In addition, some emphasis should be placed on microgravity transport processes that will play a role in the design and operation of future space facilities, such as low Reynolds number convection, boiling, evaporation or condensation, or methodologies that may be required for materials processing, such as fluidized-bed hydrogenation, electrowinning, or vapor-phase pyrolysis.
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1994a. Some results from the Surface Tension Driven Convection Experiment aboard USML-1 Spacelab.
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Last update 4/12/00 at 4:08 pm Site managed by Anne Simmons, Space Studies Board The National Academies Current Projects Publications Directories Search Site Map Feedback file:///C|/SSB_old_web/mgoppch3.htm (9 of 9)
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