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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1961

Effect of Ratio of Jet Area to Total Area and of Pressure Ratio on Lift Augmentation of Annular Jets in Ground Effect Under Static Conditions

The present investigation was undertaken to determine the effects of the ratio of jet area to total area and of the pressure ratio on the lift-augmentation characteristics of annular jets in ground effect. The investigation was made over an area-ratio range of 1.00 to 0.02 and a pressure-ratio range of about 1.04 to 1.95. Several configurations with center jets were tested through an angle-of-attack range to determine the pitching-moment characteristics. The tests were conducted in a static test room with the use of the compressed-air facilities. The results show that lift augmentation increases somewhat as the area ratio is reduced to about 0.10, below which it deteriorates due to thin jet mixing. The effect of pressure ratio on lift was negligible for the area-ratio range investigated. Calculations of the lift per air horsepower for a given base loading indicate that the greatest lift per air horsepower occurs at area ratios above 0.10, where the greatest lift augmentation occurs. The data show that annular-Jet vehicles are unstable at ratios of height above ground to nozzle diameter above about 0.10. The stability of the annular-jet vehicle can be improved by the use of large center jets. Base compartments also reduces the unstable moment.

Goodson, Kenneth W.↗
NASA NTRS1961

Low-Speed Wind-Tunnel Investigation of a Reflection Plane Wing Model Equipped with Partial-Span Jet-Augmented Flaps

An investigation to determine the aerodynamic and flow-field characteristics of three 50-percent partial-span jet-augmented flap configurations located at three spanwise positions has been conducted in the Langley 300 MPH 7- by 10-foot tunnel. The model was a semispan, rectangular unswept wing with a full-span aspect ratio of 8.3 and a thickness-to-chord ratio of 0.167. The results of this investigation showed that an inboard partial-span jet-augmented flap is less effective than a full-span blowing flap. A further reduction in effectiveness is obtained as the blaring is shifted outboard along the span. At a given lift coefficient and angle of attack, the nose-down moment about the quarter chord increases as the blowing is moved outboard. This increase in nose-down moment is due primarily to the fact that the momentum coefficient must be increased in order to obtain the same lift condition. Flow surveys indicate that the tail contribution to static longitudinal stability would be greater for the outboard blowing locations.

Otis, James H., Jr.↗
NASA NTRS2003

Ocean Primary Production Estimates from Terra MODIS and Their Dependency on Satellite Chlorophyll Alpha Algorithms

Simplistic models relating global satellite ocean color, temperature, and light to ocean net primary production (ONPP) are sensitive to the accuracy and limitations of the satellite estimate of chlorophyll and other input fields, as well as the primary productivity model. The standard MODIS ONPP product uses the new semi-analytic chlorophyll algorithm as its input for two ONPP indexes. The three primary MODIS chlorophyll Q estimates from MODIS, as well as the SeaWiFS 4 chlorophyll product, were used to assess global and regional performance in estimating ONPP for the full mission, but concentrating on 2001. The two standard ONPP algorithms were examined with 8-day and 39 kilometer resolution to quantify chlorophyll algorithm dependency of ONPP. Ancillary data (MLD from FNMOC, MODIS SSTD1, and PAR from the GSFC DAO) were identical. The standard MODIS ONPP estimates for annual production in 2001 was 59 and 58 GT C for the two ONPP algorithms. Differences in ONPP using alternate chlorophylls were on the order of 10% for global annual ONPP, but ranged to 100% regionally. On all scales the differences in ONPP were smaller between MODIS and SeaWiFS than between ONPP models, or among chlorophyll algorithms within MODIS. Largest regional ONPP differences were found in the Southern Ocean (SO). In the SO, application of the semi-analytic chlorophyll resulted in not only a magnitude difference in ONPP (2x), but also a temporal shift in the time of maximum production compared to empirical algorithms when summed over standard oceanic areas. The resulting increase in global ONPP (6-7 GT) is supported by better performance of the semi-analytic chlorophyll in the SO and other high chlorophyll regions. The differences are significant in terms of understanding regional differences and dynamics of ocean carbon transformations.

Essias, Wayne E.↗
NASA NTRS2002

Effects of moderate heart failure and functional overload on rat plantaris muscle

It is thought that changes in sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) of skeletal muscle contribute to alterations in skeletal muscle function during congestive heart failure (CHF). It is well established that exercise training can improve muscle function. However, it is unclear whether similar adaptations will result from exercise training in a CHF patient. Therefore, the purpose of this study was to determine whether skeletal muscle during moderate CHF adapts to increased activity, utilizing the functional overload (FO) model. Significant increases in plantaris mass of the CHF-FO and sham-FO groups compared with the CHF and control (sham) groups were observed. Ca(2+) uptake rates were significantly elevated in the CHF group compared with all other groups. No differences were detected in Ca(2+) uptake rates between the CHF-FO, sham, and sham-FO groups. Increases in Ca(2+) uptake rates in moderate-CHF rats were not due to changes in SERCA isoform proportions; however, FO may have attenuated the CHF-induced increases through alterations in SERCA isoform expression. Therefore, changes in skeletal muscle Ca(2+) handling during moderate CHF may be due to alterations in regulatory mechanisms, which exercise may override, by possibly altering SERCA isoform expression.

Non-NASA Center↗
NASA NTRS1994

Space shuttle flight (STS-45) of L8 myoblast cells results in the isolation of a nonfusing cell line variant

Myoblast cell cultures have been widely employed in conventional (1g) studies of biological processes because characteristics of intact muscle can be readily observed in these cultured cells. We decided to investigate the effects of spaceflight on muscle by utilizing a well characterized myoblast cell line (L8 rat myoblasts) as cultured in the recently designed Space Tissue Loss Flight Module "A" (STL-A). The STL-A is a "state of the art," compact, fully contained, automated cell culture apparatus which replaces a single mid-deck locker on the Space Shuttle. The L8 cells were successfully flown in the STL-A on the Space Shuttle STS-45 mission. Upon return to earth, reculturing of these spaceflown L8 cells (L8SF) resulted in their unexpected failure to fuse and differentiate into myotubes. This inability of the L8SF cells to fuse was found to be a permanent phenotypic alteration. Scanning electron microscopic examination of L8SF cells growing at 1g on fibronectin-coated polypropylene fibers exhibited a strikingly different morphology as compared to control cells. In addition to their failure to fuse into myotubes, L8SF cells also piled up on top of each other. When assayed in fusion-promoting soft agar, L8SF cells gave rise to substantially more and larger colonies than did either preflight (L8AT) or ground control (L8GC) cells. All data to this point indicate that flying L8 rat myoblasts on the Space Shuttle for a duration of 7-10 d at subconfluent densities results in several permanent phenotypic alterations in these cells.

STS-45 Shuttle Project↗
NASA NTRS2007

Adhesion of Lunar Dust

This paper reviews the physical characteristics of lunar dust and the effects of various fundamental forces acting on dust particles on surfaces in a lunar environment. There are transport forces and adhesion forces after contact. Mechanical forces (i.e., from rover wheels, astronaut boots and rocket engine blast) and static electric effects (from UV photo-ionization and/or tribo-electric charging) are likely to be the major contributors to the transport of dust particles. If fine regolith particles are deposited on a surface, then surface energy-related (e.g., van der Walls) adhesion forces and static-electric-image forces are likely to be the strongest contributors to adhesion. Some measurement techniques are offered to quantify the strength of adhesion forces. And finally some dust removal techniques are discussed.

Walton, Otis R.↗
NASA NTRS1994

Apparatus and methods for humidity control

Apparatus is provided which controls humidity in a gas. The apparatus employs a porous interface that is preferably a manifolded array of stainless steel tubes through whose porous surface water vapor can pass. One side of the porous interface is in contact with water and the opposing side is in contact with gas whose humidity is being controlled. Water vapor is emitted from the porous surface of the tubing into the gas when the gas is being humidified, and water vapor is removed from the gas through the porous surfaces when the gas is being dehumidified. The temperature of the porous interface relative to the gas temperature determines whether humidification or dehumidification is being carried out. The humidity in the gas is sensed and compared to the set point humidity. The water temperature, and consequently the porous interface temperature, are automatically controlled in response to changes in the gas humidity level above or below the set point. Any deviation from the set point humidity is thus corrected.

Dinauer, William R.↗
NASA NTRS2010

Charge-Spot Model for Electrostatic Forces in Simulation of Fine Particulates

The charge-spot technique for modeling the static electric forces acting between charged fine particles entails treating electric charges on individual particles as small sets of discrete point charges, located near their surfaces. This is in contrast to existing models, which assume a single charge per particle. The charge-spot technique more accurately describes the forces, torques, and moments that act on triboelectrically charged particles, especially image-charge forces acting near conducting surfaces. The discrete element method (DEM) simulation uses a truncation range to limit the number of near-neighbor charge spots via a shifted and truncated potential Coulomb interaction. The model can be readily adapted to account for induced dipoles in uncharged particles (and thus dielectrophoretic forces) by allowing two charge spots of opposite signs to be created in response to an external electric field. To account for virtual overlap during contacts, the model can be set to automatically scale down the effective charge in proportion to the amount of virtual overlap of the charge spots. This can be accomplished by mimicking the behavior of two real overlapping spherical charge clouds, or with other approximate forms. The charge-spot method much more closely resembles real non-uniform surface charge distributions that result from tribocharging than simpler approaches, which just assign a single total charge to a particle. With the charge-spot model, a single particle may have a zero net charge, but still have both positive and negative charge spots, which could produce substantial forces on the particle when it is close to other charges, when it is in an external electric field, or when near a conducting surface. Since the charge-spot model can contain any number of charges per particle, can be used with only one or two charge spots per particle for simulating charging from solar wind bombardment, or with several charge spots for simulating triboelectric charging. Adhesive image-charge forces acting on charged particles touching conducting surfaces can be up to 50 times stronger if the charge is located in discrete spots on the particle surface instead of being distributed uniformly over the surface of the particle, as is assumed by most other models. Besides being useful in modeling particulates in space and distant objects, this modeling technique is useful for electrophotography (used in copiers) and in simulating the effects of static charge in the pulmonary delivery of fine dry powders.

Walton, Otis R.↗
NASA NTRS2013

PowderSim: Lagrangian Discrete and Mesh-Free Continuum Simulation Code for Cohesive Soils

PowderSim is a calculation tool that combines a discrete-element method (DEM) module, including calibrated interparticle-interaction relationships, with a mesh-free, continuum, SPH (smoothed-particle hydrodynamics) based module that utilizes enhanced, calibrated, constitutive models capable of mimicking both large deformations and the flow behavior of regolith simulants and lunar regolith under conditions anticipated during in situ resource utilization (ISRU) operations. The major innovation introduced in PowderSim is to use a mesh-free method (SPH-based) with a calibrated and slightly modified critical-state soil mechanics constitutive model to extend the ability of the simulation tool to also address full-scale engineering systems in the continuum sense. The PowderSim software maintains the ability to address particle-scale problems, like size segregation, in selected regions with a traditional DEM module, which has improved contact physics and electrostatic interaction models.

Johnson, Scott↗
NASA NTRS2013

Wells for In Situ Extraction of Volatiles from Regolith (WIEVR)

A document discusses WIEVRs, a means to extract water ice more efficiently than previous approaches. This water may exist in subsurface deposits on the Moon, in many NEOs (Near- Earth Objects), and on Mars. The WIEVR approach utilizes heat from the Sun to vaporize subsurface ice; the water (or other volatile) vapor is transported to a surface collection vessel where it is condensed (and collected). The method does not involve mining and extracting regolith before removing the frozen volatiles, so it uses less energy and is less costly than approaches that require mining of regolith. The only drilling required for establishing the WIEVR collection/recovery system is a well-bore drill hole. In its simplest form, the WIEVRs will function without pumps, compressors, or other gas-moving equipment, relying instead on diffusive transport and thermally induced convection of the vaporized volatiles for transport to the collection location(s). These volatile extraction wells could represent a significant advance in extraction efficiency for recovery of frozen volatiles in subsurface deposits on the Moon, Mars, or other extraterrestrial bodies.

Walton, Otis R.↗
NASA NTRS2013

Microgravity Storage Vessels and Conveying-Line Feeders for Cohesive Regolith

Under microgravity, the usual methods of placing granular solids into, or extracting them from, containers or storage vessels will not function. Alternative methods are required to provide a motive force to move the material. New configurations for microgravity regolith storage vessels that do not resemble terrestrial silos, hoppers, or tanks are proposed. The microgravity-compatible bulk-material storage vessels and exit feed configurations are designed to reliably empty and feed cohesive material to transfer vessels or conveying ducts or lines without gravity. A controllable motive force drives the cohesive material to the exit opening(s), and provides a reliable means to empty storage vessels and/or to feed microgravity conveying lines. The proposed designs will function equally well in vacuum, or inside of pressurized enclosures. Typical terrestrial granular solids handling and storage equipment will not function under microgravity, since almost all such equipment relies on gravity to at least move material to an exit location or to place it in the bottom of a container. Under microgravity, there effectively are no directions of up or down, and in order to effect movement of material, some other motive force must be applied to the material. The proposed storage vessels utilize dynamic centrifugal force to effect movement of regolith whenever material needs to be removed from the storage vessel. During simple storage, no dynamic motion or forces are required. The rotation rate during emptying can be controlled to ensure that material will move to the desired exit opening, even if the material is highly cohesive, or has acquired an electrostatic charge. The general concept of this Swirl Action Utilized for Centrifugal Ejection of Regolith (SAUCER) microgravity storage unit/dynamic feeder is to have an effective slot-hopper (based on the converging angles of the top and bottom conical section of the vessel) with an exit slot around the entire periphery of the SAUCER. The basic shape of such a unit is like two Chinese straw hats (douli) - one upside down, on the bottom, and another on top; or two wokpans, one upright on the bottom and another inverted on top, with a small gap between the upright and inverted pans or hats (around the periphery). A stationary outer ring, much like an unmounted bicycle tire, surrounds the gap between the two coaxial, nearly conical pieces, forming the top and bottom of the unit.

Walton, Otis R.↗
NASA NTRS2013

Flexible Mechanical Conveyors for Regolith Extraction and Transport

A report describes flexible mechanical conveying systems for transporting fine cohesive regolith under microgravity and vacuum conditions. They are totally enclosed, virtually dust-free, and can include enough flexibility in the conveying path to enable an expanded range of extraction and transport scenarios, including nonlinear drill-holes and excavation of enlarged subsurface openings without large entry holes. The design of the conveyors is a modification of conventional screw conveyors such that the central screw-shaft and the outer housing or conveyingtube have a degree of bending flexibility, allowing the conveyors to become nonlinear conveying systems that can convey around gentle bends. The central flexible shaft is similar to those used in common tools like a weed whacker, consisting of multiple layers of tightly wound wires around a central wire core. Utilization of compliant components (screw blade or outer wall) increases the robustness of the conveying, allowing an occasional oversized particle to pass hough the conveyor without causing a jam or stoppage

Walton, Otis R.↗
NASA NTRS2013

Centrifugal Sieve for Gravity-Level-Independent Size Segregation of Granular Materials

Conventional size segregation or screening in batch mode, using stacked vibrated screens, is often a time-consuming process. Utilization of centrifugal force instead of gravity as the primary body force can significantly shorten the time to segregate feedstock into a set of different-sized fractions. Likewise, under reduced gravity or microgravity, a centrifugal sieve system would function as well as it does terrestrially. When vibratory and mechanical blade sieving screens designed for terrestrial conditions were tested under lunar gravity conditions, they did not function well. The centrifugal sieving design of this technology overcomes the issues that prevented sieves designed for terrestrial conditions from functioning under reduced gravity. These sieves feature a rotating outer (cylindrical or conical) screen wall, rotating fast enough for the centrifugal forces near the wall to hold granular material against the rotating screen. Conventional centrifugal sieves have a stationary screen and rapidly rotating blades that shear the granular solid near the stationary screen, and effect the sieving process assisted by the airflow inside the unit. The centrifugal sieves of this new design may (or may not) have an inner blade or blades, moving relative to the rotating wall screen. Some continuous flow embodiments would have no inner auger or blades, but achieve axial motion through vibration. In all cases, the shearing action is gentler than conventional centrifugal sieves, which have very high velocity differences between the stationary outer screen and the rapidly rotating blades. The new design does not depend on airflow in the sieving unit, so it will function just as well in vacuum as in air. One advantage of the innovation for batch sieving is that a batch-mode centrifugal sieve may accomplish the same sieving operation in much less time than a conventional stacked set of vibrated screens (which utilize gravity as the primary driving force for size separation). In continuous mode, the centrifugal sieves can provide steady streams of fine and coarse material separated from a mixed feedstock flow stream. The centrifugal sieves can be scaled to any desired size and/or mass flow rate. Thus, they could be made in sizes suitable for small robotic exploratory missions, or for semi-permanent processing of regolith for extraction of volatiles of minerals. An advantage of the continuous-mode system is that it can be made with absolutely no gravity flow components for feeding material into, or for extracting the separated size streams from, the centrifugal sieve. Thus, the system is capable of functioning in a true microgravity environment. Another advantage of the continuous-mode system is that some embodiments of the innovation have no internal blades or vanes, and thus, can be designed to handle a very wide range of feedstock sizes, including occasional very large oversized pieces, without jamming or seizing up.

Walton, Otis R.↗
NASA NTRS2015

Centrifugal Size-Separation Sieve for Granular Materials

A centrifugal sieve and method utilizes centrifugal force in rapidly-rotated cylindrical or conical screens as the primary body force contributing to size segregation. Within the centrifugal acceleration field, vibration and/or shearing flows are induced to facilitate size segregation and eventual separation of the fines from the coarse material. Inside a rotating cylindrical or conical screen, a separately-rotated screw auger blade can be used to transport material along the rotating cylinder or conical wall and to induce shearing in the material.

Walton, Otis↗
NASA NTRS2016

Vertical-Screw-Auger Conveyer Feeder

A conical feeder is attached to a vertically conveying screw auger. The feeder is equipped with scoops and rotated from the surface to force-feed regolith the auger. Additional scoops are possible by adding a cylindrical section above the conical funnel section. Such then allows the unit to collect material from swaths larger in diameter than the enclosing casing pipe of the screw auger. A third element includes a flexible screw auger. All three can be used in combination in microgravity and zero atmosphere environments to drill and recover a wide area of subsurface regolith and entrained volatiles through a single access point on the surface.

Walton, Otis↗
NASA NTRS2017

Granular Material Scoop and Near-Vertical Lifting Feeder/Conveyor

An integrated granular-material scoop and near-vertical lifting feeder/conveyor includes special connections and skirts between a bullnose rotating scoop and an open-helical screw that provides the rotations and material lift and evacuation. A conical working-face of the bullnose rotating scoop has symmetrically distributed graters and vents to break loose and force-in granular material from natural deposits and cargo holds. The bullnose rotating scoop and the open-helical screw its attached to move the material into a continuous layer on the inside surface of an outer stationary sheathing. A motor drive attached to the open-helical screw above at the delivery end provides the lifting force necessary.

Walton, Otis↗
NASA NTRS2018

A Conceptual Enterprise Framework for Managing Scientific Data Stewardship

Scientific data stewardship is an important part of long-term preservation and the use/reuse of digital research data. It is critical for ensuring trustworthiness of data, products, and services, which is important for decision-making. Recent U.S. federal government directives and scientific organization guidelines have levied specific requirements, increasing the need for a more formal approach to ensuring that stewardship activities support compliance verification and reporting. However, many science data centers lack an integrated, systematic, and holistic framework to support such efforts. The current business- and process-oriented stewardship frameworks are too costly and lengthy for most data centers to implement. They often do not explicitly address the federal stewardship requirements and/or the uniqueness of geospatial data. This work proposes a data-centric conceptual enterprise framework for managing stewardship activities, based on the philosophy behind the Plan-Do-Check-Act (PDCA) cycle, a proven industrial concept. This framework, which includes the application of maturity assessment models, allows for quantitative evaluation of how organizations manage their stewardship activities and supports informed decision-making for continual improvement towards full compliance with federal, agency, and user requirements.

Scientific data stewardship↗