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Research Thrusts |
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Engineering Education Innovation
As the world continues to change with globalization and technological advances so must engineering education p...
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Advanced Power System
In the face of an impending energy crisis, the Advanced Power Systems research center is exploring alternative...
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Space Systems
The Space Systems Research group is creating innovative electric propulsion systems to make space travel more ...
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Mechanics of Multi-scale Materials
The Mechanics of Multi-scale Materials research group uncovers the relationships of structures across the full...
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Multi-scale Sensors and Systems
The Multi-scale Sensors and Systems Research Group specializes in the design, fabrication, integration, and te...
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Sustainable Manufacturing and Design
Many of the campus research efforts on sustainability are coordinated by the Sustainable Futures Institute (SF...
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Research Projects
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Microscale Investigation of the Thermo-Fluid Transport in the Transition Film Region of an Evaporating Capillary Meniscus |
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Project Date:
2004-2007 |
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Web Site
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Jeffrey Allen
Primary Investigator
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Joe Hernandez
Co-Primary Investigator
Ken Kihm
Co-Primary Investigator
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Sponsor:
National Aeronautics and Space Administration - John H. Glenn Research Center
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In low gravity, the solid-liquid inter-molecular surface forces are comparable to capillary and gravitational forces at significantly greater film thickness (1 approximately 10 microns), than is possible in earth's gravity (0.01 approximately 0.1 microns). Therefore, advanced microscale optical techniques to measure the film thickness, heat transport, and liquid velocity fields in the transition film region of an extended meniscus; probing, for the first the thermo-fluid transport inside this very important micro-scale region. Since the project initiation in the beginning of 2002, a preliminary ground study has been done to implement a Molecular Fluorescence Tracking Velocimetry (MFTV) system, utilizing caged fluorophores of approximately 10 nm in size as seeding particles, ultimately to measure the velocity profiles in the thin film region. Fizeau interferometry in conjunction with a microscope has been completed to measure the thin film slope and thickness variations. Although the extension of the thin film dimensions under microgravity will be achieved by using a conical evaporator, a simpler and easy-to-fabricate evaporator has been designed and constructed for the ground test. Note that the experimental setup is to maintain a constant liquid volume and liquid pressure in the capillary region of the evaporating meniscus so as to insure quasi-stationary conditions during measurements on the transition film region. In addition, the new Confocal Laser Scanning Microscopy (CLSM), available at Dr. Kihm's laboratory, has been tested for its optical sectioning capability allowing a depth-wise resolution for MFTV applications. A micro-heater array has been fabricated using photo-lithography to etch and vapor deposit platinum films. The heater array is packaged on a thin silicon substrate and then the upper face of the substrate is planarized to form a smooth contact surface. Individual heater elements (20-micron-wide and 20-mm long) are designed to maintain either a constant surface temperature or a controlled temperature variation. A Wheatstone bridge circuit controls each heater element with the temperature-dependent heater resistance value as a feedback signal.
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