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Weislogel, Mark

Publications and source records attributed to Weislogel, Mark.

16 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Student Design Challenges in Capillary Flow

For some grade 8-12 students, capillary flow has bridged the gap between the classroom and research facility, from normal gravity to microgravity. In the past four years, NASA and the Portland State University (PSU) have jointly challenged students to design test cells, using Computer-Aided Design (CAD), to study capillary action in microgravity as PSU has done on the International Space Station (ISS). Using the student-submitted CAD drawings, the test cells were manufactured by PSU and tested in their 2.1-second drop tower. The microgravity results were made available online for student analysis and reporting. Over 100 such experiments have been conducted, where there has been participation from 15 states plus a German school for the children of U.S. military personnel. In 2016, a related NASA challenge was held in partnership with the ASGSR, again, based on the research conducted by PSU. In this challenge, grade 9-12 students designed and built devices using capillary action to launch droplets as far as possible in NASAs 2.2 Second Drop Tower. Example results will be presented by students at this conference. The challenges engage students in ISS science and technology and can inspire them to pursue technical careers.

capillary flow↗
NASA NTRS2016

Thirsty Walls: A New Paradigm for Air Revitalization in Life Support

This Phase I project Summary will be formatted as a series of summary statements, with additional comments. The summary statements are intended to focus on the most significant findings and discoveries – things that the project team knows now, but we didn’t know at the beginning of the project: 1) Direct Contact Between Gases is an ECLS (Environmental Control and Life Support) System enabling capability; 2) CO2 capture using liquid sorbents in microgravity is feasible; 3) There are other ways to contact gases and liquids – but thin film capillary techniques are new, exciting, and have amazing potential; 4) ECLS system reliability is the key to exploration missions – the key to reliability is having system attributes that favor reliability; 5) The processes with favorable reliability attributes tend to be biological; 6) The single greatest impact on launch mass of an ECLS system is water. The best way to enable biological water processing is to develop a capillary based method of urine capture that doesn’t use pretreat chemicals; 7) There is good, promising, forward design and development work – but no fundamental “show stoppers” – to develop a thin film liquid sorbent CO2 capture system; 8) The most capable Ionic Liquids are not presently feasible, but other chemically active liquids can be used to make an effective thin film CO2 capture device; 9) The C9 reduced gravity flight showed feasibility – and taught us about flow instability issues; 10) Capillary fluid management has ECLS system wide implications.

CO2↗
NASA NTRS2015

Thirsty Walls: A New Paradigm for Air Revitalization in Life Support

Carbon Dioxide removal systems on submarines are compact and reliable. They use solubility chemistry. They spray a Carbon Dioxide adsorbing chemical directly into the air stream, and allow the liquid to settle. Carbon Dioxide removal systems on ISS are large and need repair. They use adsorption chemistry. They force air through a bed packed with granular zeolite, and heat the bed to desorb the Carbon Dioxide. The thermal cycles cause the zeolite to dust. New advances in additive manufacturing, and a better understanding of uid behavior in microgravity make it possible to expose a liquid directly to air in a microgravity environment. It is now practical to use submarine style solubility chemistry for atmosphere revitalization in space. It is now possible to develop space systems that achieve submarine levels of reliability. New developments in Ionic Liquid research make it possible to match the solubility performance characteristics of MEA used on submarines - with Ionic Liquids that do not release chemical vapors into the air. "Thirsty Walls" provide gentle, passive contact between ventilation air and Air Revitalization functions of temperature control, relative humidity control, and Carbon Dioxide removal. "Thirsty Walls" eliminates the need of large blowers and compressors that need to force air at high velocities through restrictive Air Revitalization hardware.

Graf, John↗
NASA NTRS2014

Capillary Flows Along Open Channel Conduits: The Open-Star Section

Capillary rise in tubes, channels, and grooves has received significant attention in the literature for over 100 years. In yet another incremental extension of such work, a transient capillary rise problem is solved for spontaneous flow along an interconnected array of open channels forming what is referred to as an 'open-star' section. This geometry possesses several attractive characteristics including passive phase separations and high diffusive gas transport. Despite the complex geometry, novel and convenient approximations for capillary pressure and viscous resistance enable closed form predictions of the flow. As part of the solution, a combined scaling approach is applied that identifies unsteady-inertial-capillary, convective-inertial-capillary, and visco-capillary transient regimes in a single parameter. Drop tower experiments are performed employing 3-D printed conduits to corroborate all findings.

Weislogel, Mark↗
NASA NTRS2013

Zero-gravity Mean Free Surface Curvature of a Confined Liquid in a Radially-Vaned Container

A variety of increasingly intricate container geometries are under consideration for the passive manipulation of liquids aboard spacecraft where the impact of gravity may be neglected. In this study we examine the mean curvature of a liquid volume confined within a radial array of disconnected vanes of infinite extent. This particular geometry possesses a number of desirable characteristics relevant to waste water treatment aboard spacecraft for life support. It is observed that under certain conditions the slender shape of the free surface approaches an asymptote, which can be predicted analytically using new hybrid boundary conditions proposed herein. This contribution represents possibly the final extension of what has been referred to as the method of de Lazzer et al. (1996). The method enables the integration of the Young-Laplace equation over a domain with its boundaries, including the wetted portion of the solid boundaries, symmetry planes, and circular arcs representing free surfaces at the center plane of the liquid body. Asymptotic solutions at several limits are obtained and the analysis is confirmed with numerical computations.

Chen, Yongkang↗
NASA NTRS2012

Engineered Multifunctional Surfaces for Fluid Handling

Designs incorporating variations in capillary geometry and hydrophilic and/or antibacterial surface properties have been developed that are capable of passive gas/liquid separation and passive water flow. These designs can incorporate capillary grooves and/or surfaces arranged to create linear and circumferential capillary geometry at the micro and macro scale, radial fin configurations, micro holes and patterns, and combinations of the above. The antibacterial property of this design inhibits the growth of bacteria or the development of biofilm. The hydrophilic property reduces the water contact angle with a treated substrate such that water spreads into a thin layer atop the treated surface. These antibacterial and hydrophilic properties applied to a thermally conductive surface, combined with capillary geometry, create a novel heat exchanger capable of condensing water from a humid, two-phase water and gas flow onto the treated heat exchanger surfaces, and passively separating the condensed water from the gas flow in a reduced gravity application. The overall process to generate the antibacterial and hydrophilic properties includes multiple steps to generate the two different surface properties, and can be divided into two major steps. Step 1 uses a magnetron-based sputtering technique to implant the silver atoms into the base material. A layer of silver is built up on top of the base material. Completion of this step provides the antibacterial property. Step 2 uses a cold-plasma technique to generate the hydrophilic surface property on top of the silver layer generated in Step 1. Completion of this step provides the hydrophilic property in addition to the antibacterial property. Thermally conductive materials are fabricated and then treated to create the antibacterial and hydrophilic surface properties. The individual parts are assembled to create a condensing heat exchanger with antibacterial and hydrophilic surface properties and capillary geometry, which is capable of passive phase separation in a reduced gravity application. The plasma processes for creating antibacterial and hydrophilic surface properties are suitable for applications where water is present on an exposed surface for an extended time, such that bacteria or biofilms could form, and where there is a need to manage the water on the surface. The processes are also suitable for applications where only the hydrophilic property is needed. In particular, the processes are applicable to condensing heat exchangers (CHXs), which benefit from the antibacterial properties as well as the hydrophilic properties. Water condensing onto the control surfaces of the CHX will provide the moist conditions necessary for the growth of bacteria and the formation of biofilms. The antibacterial properties of the base layer (silver) will mitigate and prevent the growth of bacteria and formation of biofilms that would otherwise reduce the CHX performance. In addition, the hydrophilic properties reduce the water contact angle and prevent water droplets from bridging between control surfaces. Overall, the hydrophilic properties reduce the pressure drop across the CHX.

Thomas, Chris↗
NASA NTRS2012

SE-FIT

The mathematical theory of capillary surfaces has developed steadily over the centuries, but it was not until the last few decades that new technologies have put a more urgent demand on a substantially more qualitative and quantitative understanding of phenomena relating to capillarity in general. So far, the new theory development successfully predicts the behavior of capillary surfaces for special cases. However, an efficient quantitative mathematical prediction of capillary phenomena related to the shape and stability of geometrically complex equilibrium capillary surfaces remains a significant challenge. As one of many numerical tools, the open-source Surface Evolver (SE) algorithm has played an important role over the last two decades. The current effort was undertaken to provide a front-end to enhance the accessibility of SE for the purposes of design and analysis. Like SE, the new code is open-source and will remain under development for the foreseeable future. The ultimate goal of the current Surface Evolver Fluid Interface Tool (SEFIT) development is to build a fully integrated front-end with a set of graphical user interface (GUI) elements. Such a front-end enables the access to functionalities that are developed along with the GUIs to deal with pre-processing, convergence computation operation, and post-processing. In other words, SE-FIT is not just a GUI front-end, but an integrated environment that can perform sophisticated computational tasks, e.g. importing industry standard file formats and employing parameter sweep functions, which are both lacking in SE, and require minimal interaction by the user. These functions are created using a mixture of Visual Basic and the SE script language. These form the foundation for a high-performance front-end that substantially simplifies use without sacrificing the proven capabilities of SE. The real power of SE-FIT lies in its automated pre-processing, pre-defined geometries, convergence computation operation, computational diagnostic tools, and crash-handling capabilities to sustain extensive computations. SE-FIT performance is enabled by its so-called file-layer mechanism. During the early stages of SE-FIT development, it became necessary to modify the original SE code to enable capabilities required for an enhanced and synchronized communication. To this end, a file-layer was created that serves as a command buffer to ensure a continuous and sequential execution of commands sent from the front-end to SE. It also establishes a proper means for handling crashes. The file layer logs input commands and SE output; it also supports user interruption requests, back and forward operation (i.e. undo and redo), and others. It especially enables the batch mode computation of a series of equilibrium surfaces and the searching of critical parameter values in studying the stability of capillary surfaces. In this way, the modified SE significantly extends the capabilities of the original SE.

Chen, Yongkang↗
NASA NTRS2011

A Zero-Gravity Cup for Drinking Beverages in Microgravity

To date, the method for astronauts to drink liquids in microgravity or weightless environments is to suck the liquid from a bag or pouch through a straw. A new beverage cup works in microgravity and allows astronauts to drink liquids from a cup in a manner consistent with that on Earth. The cup is capable of holding beverages with an angled channel running along the wall from the bottom to the lip. In microgravity, a beverage is placed into the cup using the galley dispenser. The angled channel acts as an open passage that contains only two sides where capillary forces move the liquid along the channel until it reaches the top lip where the forces reach an equilibrium and the flow stops. When one sips the liquid at the lip of the channel, the capillary force equilibrium is upset and more liquid flows to the lip from the reservoir at the bottom to re-establish the equilibrium. This sipping process can continue until the total liquid contents of the cup is consumed, leaving only a few residual drops about the same quantity as in a ceramic cup when it is drunk dry on Earth.

Pettit, Donald R.↗
NASA NTRS2004

Freeze Tolerant Radiator for an Advanced EMU

During an Extravehicular Activity (EVA), the astronaut s metabolic heat and the heat produced by the Portable Life Support Unit (PLSS) must be rejected. This heat load is currently rejected by a sublimator, which vents up to eight pounds of water each EVA. However, for advanced space missions of the future, water venting to space needs to be minimized because resupply impacts from earth will be prohibitive. If this heat load could be radiated to space from the PLSS, which has enough surface area to radiate most of the heat, the amount of water now vented could be greatly reduced. Unfortunately, a radiator rejects heat at a relatively constant rate, but the astronauts generate a variable heat load depending on how hard they are working. Without a way to vary the heat removal rate, the astronaut would experience cold discomfort or even frostbite. A proven method allowing a radiator to be turned-down is to sequentially allow tubes that carry the heat transfer fluid to the radiator to freeze. A drawback of current freezable radiators using this method is that they are far to heavy for use on a PLSS, because they use heavy construction to prevent the tubes from bursting as they freeze and thaw. This creates the need for a large radiator to reject most of the heat but with a lightweight tube that doesn t burst as it freezes and thaws. The new freezable radiator for the Extravehicular Mobility Unit (EMU) has features to accommodate the expansion of the radiator fluid when it freezes, and still have the high tube to fin conductance needed to minimize the number and weight of the tubes. Radiator fluid candidates are water and a propylene glycol-water mixture. This design maintains all materials within their elastic limits so that large volume changes can be achieved without breaking the tube. This concept couples this elastic expansion with an extremely lightweight, extremely high conductivity carbon fiber fin that can carry the heat needed to thaw a frozen tube. By using most of the exposed surface area of the PLSS as a radiator, the system can reject about 75% of the highest heat load, and reduce the loss of water through sublimation by a factor of four. The proposed radiator and a small water tank can be no heavier than the current system.

Copeland, Robert J.↗
NASA NTRS2000

Development of a Solid Chlorate Backup Oxygen Delivery System for the International Space Station

The International Space Station (ISS) Program requires that there always be a 45 calendar day contingency supply of breathing oxygen. In the early assembly stages, there is only one flight system, the Russian Solid Fuel Oxygen Generator (SFOG), that can meet that requirement. To better ensure the contingency oxygen supply, the Crew and Thermal Systems Division was directed to develop a flight hardware system that can meet all contingency oxygen requirements for ISS. Such a system, called the Backup Oxygen Candle System (BOCS), has been built and tested. The BOCS consists of 33 chlorate candles, a thermal containment apparatus, support equipment and packaging. The thermal containment apparatus utilizes the O2 produced by the candle as the motive stream in an ejector to passively cool the candle during operation.

Graf, John↗
NASA NTRS1998

Results From the USML-2 Interface Configuration Experiment

Mathematical theory predicts that small changes in container shape or in contact angle can give rise to large shifts of liquid in a microgravity environment. For studying such shifts, container shapes are described that were flown on board the Space Shuttle USML-2 mission as part of the Glovebox Interface Configuration Experiment. These containers are in the form of a circular cylinder with two diametrically opposed "canonical proboscis" protrusions. The containers were designed with the goal of having two desirable properties -that sufficient liquid would participate in the shift to permit easy observation, and that the change would be abrupt enough to allow accurate determination of critical contact angle. The observed behavior for these vessels is depicted, along with behavior for a movable wedge vessel, which also formed part of the experiment. The experimental results support the validity of the concept of macroscopic contact angle, basic to the theory, and thereby its use in predicting fluid behavior under reduced gravity. The results indicate, as well, the role of hysteresis in impeding orientation to equilibrium.

Concus, Paul↗
NASA NTRS1994

Interface Configuration Experiment: Preliminary Results

The Interface Configuration Experiment (ICE) was carried out on USML-1 to investigate liquid-gas interfaces in certain rotationally-symmetric containers having prescribed, mathematically derived shapes. These containers have the property that they admit an entire continuum of distinct equilibrium rotationally-symmetric interfaces for a given liquid volume and contact angle. Furthermore, it can be shown that none of these interfaces can be stable. It was found, after the containers were filled in orbit, that an initial equilibrium interface from the symmetric continuum re-oriented, when perturbed, to a stable interface that was not rotationally symmetric, in accordance with the mathematical theory.

Concus, Paul↗
NASA NTRS1993

An interface configuration experiment on USML-1

Experiments were carried out for 'exotic' rotationally symmetric containers aboard the first NASA United States Microgravity Laboratory Space Shuttle flight (USML-1). The containers have the property that they admit an entire continuum of distinct equilibrium rotationally-symmetric capillary free-surfaces for a given liquid volume and contact angle. It was found, after the containers were filled in orbit, that an initial equilibrium interface from the symmetric continuum reoriented, when perturbed, to a stable interface that was not rotationally symmetric, as predicted by the mathematical theory.

Concus, Paul↗
NASA NTRS1991

Drop-tower experiments for capillary surfaces in an exotic container

Low-gravity drop-tower experiments are carried out for an 'exotic' rotationally-symmetric container, which admits an entire continuum of distinct equilibrium symmetric capillary free surfaces. It is found that an initial equilibrium planer interface, a member of the continuum, will reorient toward a non-symmetric interface, as predicted by recent mathematical theory.

Concus, Paul↗
NASA NTRS1991

Stability of capillary surfaces

An extensive data set quantifying the stability limits of capillary surfaces for a wide range of fluid properties, container geometry, and input disturbance and orientation does not currently exist. To begin to provide such a data set an experimental apparatus has been designed for which the dynamics and stability of fluid interfaces will be investigated. The apparatus consists primarily of a programmable shaker table and a high speed motion picture and video camera for viewing the fluid surface as drop tower tests will be performed to note the stability of a variety of surface/vessel configurations.

Weislogel, Mark↗