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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

The coupled dynamics of fluids and spacecraft in low gravity and low gravity fluid measurement

The very large mass fraction of liquids stored on broad current and future generation spacecraft has made critical the technologies of describing the fluid-spacecraft dynamics and measuring or gauging the fluid. Combined efforts in these areas are described, and preliminary results are presented. The coupled dynamics of fluids and spacecraft in low gravity study is characterizing the parametric behavior of fluid-spacecraft systems in which interaction between the fluid and spacecraft dynamics is encountered. Particular emphasis is given to the importance of nonlinear fluid free surface phenomena to the coupled dynamics. An experimental apparatus has been developed for demonstrating a coupled fluid-spacecraft system. In these experiments, slosh force signals are fed back to a model tank actuator through a tunable analog second order integration circuit. In this manner, the tank motion is coupled to the resulting slosh force. Results are being obtained in 1-g and in low-g (on the NASA KC-135) using dynamic systems nondimensionally identical except for the Bond numbers.

Hansman, R. John↗
NASA NTRS1987

Microgravity fluid management in two-phase thermal systems

Initial studies have indicated that in comparison to an all liquid single phase system, a two-phase liquid/vapor thermal control system requires significantly lower pumping power, demonstrates more isothermal control characteristics, and allows greater operational flexibility in heat load placement. As a function of JSC's Work Package responsibility for thermal management of space station equipment external to the pressurized modules, prototype development programs were initiated on the Two-Phase Thermal Bus System (TBS) and the Space Erectable Radiator System (SERS). JSC currently has several programs underway to enhance the understanding of two-phase fluid flow characteristics. The objective of one of these programs (sponsored by the Microgravity Science and Applications Division at NASA-Headquarters) is to design, fabricate, and fly a two-phase flow regime mapping experiment in the Shuttle vehicle mid-deck. Another program, sponsored by OAST, involves the testing of a two-phase thermal transport loop aboard the KC-135 reduced gravity aircraft to identify system implications of pressure drop variation as a function of the flow quality and flow regime present in a representative thermal system.

Parish, Richard C.↗
NASA NTRS1987

Effect of STS space suit on astronaut dominant upper limb EVA work performance

The STS Space Suited and unsuited dominant upper limb performance was evaluated in order to quantify future EVA astronaut skeletal muscle upper limb performance expectations. Testing was performed with subjects standing in EVA STS foot restraints. Data was collected with a CYBEX Dynamometer enclosed in a waterproof container. Control data was taken in one g. During one g testing, weight of the Space Suit was relieved from the subject via an overhead crane with a special connection to the PLSS of the suit. Experimental data was acquired during simulated zero g, accomplished by neutral buoyancy in the Weightless Environment Training Facility. Unsuited subjects became neutrally buoyant via SCUBA BC vests. Actual zero g experimental data was collected during parabolic arc flights on board NASA's modified KC-135 aircraft. During all test conditions, subjects performed five EVA work tasks requiring dominant upper limb performance and ten individual joint articulation movements. Dynamometer velocities for each tested movement were 0 deg/sec, 30 or 60 deg/sec and 120 or 180 deg/sec, depending on the test, with three repetitions per test. Performance was measured in foot pounds of torque.

Greenisen, Michael C.↗
NASA NTRS1986

Historical development

The history of the U.S. Microgravity Science and Applications program is summarized, noting significant discoveries in the first decade of the program. The experiments were performed to understand the behavior of liquid propellants (and other fluids), liquid melt zones, and containerless liquid suspension systems in microgravity. Investigations were carried out with a drop tower, on KC-135 and solid rocket flights, and during Apollo, Skylab and Apollo-Soyuz missions.

Naumann, R. J.↗
NASA NTRS1987

Electrodeposition of metals and metal/cermet composites in low gravity

Electrodeposition experiments were carried out on the bench and a KC-135 aircraft at 0.01 g in anticipation of microgravity flights on NASA's Space Transportation System Shuttle. Experimental results obtained by interferometry compare concentration gradients as a function of time in the vicinity of a reducing electrode (cathode) for Cu(+2) and Co(+2) electrodeposition cells. No difference was found between bench and 0.01 g produced gradients for a .1M CuSO4 cell, but a significant difference was noted between the gradients in a 1M CoSO4 cell even though the bench cells were operated in a nonconvecting shielded (cathode over anode) mode. The gradient for Co(+2) depletion produced at 0.01 g was greater and the entire layer was thicker than found on the bench. Neutral buoyancy/matched density codeposition experiments were performed on the bench in an attempt to physically duplicate the results of metal/cermet codepositions in microgravity. Polystyrene spheres with average diameter 11.8 microns and density approximately matching that of 1M CoSO4 were utilized to emulate nonsedimenting cermets in microgravity. The cells were operated in a shielded convectionless mode. Comparison with literature data on codeposition with stirred cells indicate significant improvement in volume percent neutral occluded in the depositing metal matrix. A multicell electrodeposition flight apparatus that has been designed, constructed and is undergoing testing is discussed.

Riley, Clyde↗
NASA NTRS1986

Microstructural variations induced by gravity level during directional solidification of near-eutectic iron-carbon type alloys

The effects of gravity on the microstructure of directionally solidified near-eutectic cast irons are studied, using a Bridgman-type automatic directional solidification furnace aboard a NASA KC-135 aircraft which flies parabolic arcs and generates alternating periods of low-g (0.01 to 0.001 g, 30 seconds long) and high-g (1.8 g, 1.5 minutes long). Results show a refinement of the interlamellar spacing of the eutectic during low-g processing of metastable Fe-C eutectic alloys. Low-g processing of stable Fe-C-Si eutectic alloys (lamellar or spheroidal graphic) results in a coarsening of the eutectic grain structure. Secondary dendrite arm spacing of austenite increases in low-g and decreases in high-g. The effectiveness of low-gravity in the removal of buoyancy-driven graphite phase segregation is demonstrated.

Stefanescu, Doru M.↗
NASA NTRS1986

Current program to investigate phenomena in a microgravity environment

Current NASA Microgravity Science and Applications Division Shuttle and terrestrial experiments to acquire basic data for space-based materials processing activities are summarized. The research is carried out to increase the understanding and to improve ground-based and space-based processing, to enhance the understanding of basic physical phenomena, and to characterize the forces which effect low-gravity processing. The main areas of research are crystal growth, metallic alloy solidification, bioseparation processes, blood rheology, containerless processing, and studies of combustion processes, chemical and transport phenomena, cloud microphysics and fluid behavior and surface phenomena in microgravity. Specific experiments, which exemplify the research goals and were performed on KC-135 flights along Keplerian trajectories and on Shuttle missions, are described.

Oran, William A.↗
NASA NTRS1986

The effect of gravity level on the average primary dendritic spacing of a directionally solidified superalloy

The effect of alternating low (0.01 g) and high (1.8 g) gravity force on the primary spacings in the dendrite structure in a directionally solidified Ni-based superalloy (PWA 1480, containing 5 pct Co, 10 pct Cr, 4 pct W, 12 pct Ta, 5 pct Al, 1.5 pct Ti, and the balance Ni) was investigated using samples solidified in a directional solidification furnace aboard the NASA KC-135 aircraft that made a series of low-g parabolas. The cross-section slices for each growth rate were polished and etched with Kallings II, and the primary dendritic arm spacings were measured using the method of Jacobi and Schwerdtfeger (1976). The arm spacings were found to fluctuate with gravity force, increasing as the gravity level decreased, and growing finer as gravity increased.

Mccay, M. H.↗
NASA NTRS1987

Electrical properties of Al-In-Sn alloys directionally solidified in high and low gravitational fields

The Al-In-Sn alloys were directionally solidified in the NASA KC-135 aircraft which flies a series of parabolas to generate high (high-g) and low (low-g) gravity forces parallel to the longitudinal growth axis. Thus, for a given sample, successive sections can be identified which were solidified in high-g and low-g. Measurements of the electronic properties of the samples reveal that: the resistivity of the low-g sections is larger (about a factor of 10) than that of the high-g sections; the low-g sections behave conductively like a semi-metal, while the high-g sections are essentially metallic; and both high-g and low-g sections are superconducting but the superconducting transition temperature of the low-g sections is 1 K higher than that of the high-g sections.

Wu, M. K.↗
NASA NTRS1988

Furnace For Rapid Melting And Freezing

Proposed furnace rapidly heats and cools specimens in material-processing experiments. Preheated specimen heated rapidly above melting temperature by contact with hotter, more massive object. Once molten, cooled rapidly with flowing gas. Particularly useful for experiments requiring artificial low gravitation produced by flying KC-135 airplanes in parabolic trajectories.

Ethridge, Edwin C.↗
NASA NTRS1988

Translating Furnace For Fast Melting And Freezing

Developmental translating-furnace apparatus used to make ceramic/metal composite materials during parabolic trajectories of KC-135 airplane simulating low gravity. Mathematical modeling shows apparatus able both to melt metal alloys and to solidify resulting composite specimens during 22-to-30-second low-gravity intervals. Furnace assembly moves along crucible in programmed manner to preheat, melt, and solidfy specimen during interval to less than 22 second.

Workman, F.↗
NASA NTRS1987

Development of on-orbit fluid gaging techniques

The objective was to measure liquid mass to plus or minus 1 percent in two-phase tanks in orbit. Viewgraphs present information on concept selection, program status and anticipated results. The program aims at test results showing 1 percent accuracy, the development of a breadboard test article usable in the lab or aboard a KC-135, and a concept that will permit flight article design to proceed.

Mord, Allan↗
NASA NTRS1987

Study of the production of some superconducting and magnetic materials by solidification in the drop tube and drop tower

A systematic study on the relationship between the microstructure and physical properties of several superconducting materials prepared by solidification in low gravity was conducted. Further study of the materials, such as the applications of hydrostatic pressure which is known to be an effective mean to vary the electronic structure of materials, in conjunction with the detailed microstructure analysis of the samples was also performed to better understand the low gravity effects on the enhancement of the electronic properties. Results of the studies on the directionally solidified AlInSn alloys processed in the KC-135 aircraft and immiscible GaBi alloy prepared during free fall in the Marshall Space Flight Center Drop Tower are presented.

Wu, M. K.↗
NASA NTRS1988

Microgravity two-phase fluid flow pattern modeling

When gas and liquid mixtures flow in a pipe, the distribution of the two phases may take many forms. A flow pattern, or flow regime, is the characteristic spatial distribution of the phases of flow in a pipe. Because heat transfer and pressure drop are dependent on the characteristic distribution of phases, it is necessary to describe flow patterns in an appropriate manner so that a hydrodynamic or heat transfer theory applicable to that can be chosen. A theoretical two phase flow regime transition map under a microgravity environment was developed on physical concepts. These transitions use four basic flow patterns: dispersed flow, slug flow, stratified flow, and annular flow. The forces considered are body force, surface tension force, inertial force, friction, and the force from eddy turbulent fluctuation. Three dimensionless parameters were developed. Because these transition boundaries were developed based on physical concepts, they should be applicable to flow regimes occurring in various design conditions. Because the flow pattern data from KC-135 experiments are insufficient to verify these theoretical transition lines completely, an adiabatic experiment for flow regime analysis is recommended.

Lee, Doojeong↗
NASA NTRS1987

The use of the logistic model in space motion sickness prediction

The one-equation and the two-equation logistic models were used to predict subjects' susceptibility to motion sickness in KC-135 parabolic flights using data from other ground-based motion sickness tests. The results show that the logistic models correctly predicted substantially more cases (an average of 13 percent) in the data subset used for model building. Overall, the logistic models ranged from 53 to 65 percent predictions of the three endpoint parameters, whereas the Bayes linear discriminant procedure ranged from 48 to 65 percent correct for the cross validation sample.

Lin, Karl K.↗
NASA NTRS1988

Influence of high and low gravity on convection around growing crystals

Crystals growing from solution lead to changes in solution concentration which normally lead to convection in a gravitational field. This enhances local supersaturation and changes the growth rate and shape of the crystal. Experiments are described where velocity is enhanced by moving the crystal through the solution, and reduced to low values by performing the growth experiments in the low g environment of a KC-135 aircraft parabola. Differences of refractive index enable the convection to be viewed in an optical system. Results show the importance of even low convection on growth, and the ultimate composition and habit of the crystal.

Hallett, J.↗
NASA NTRS1988

Dynamic shear of granular material under variable gravity conditions

This paper describes some experiments with granular materials which recently have been conducted aboard the NASA KC-135 aircraft during variable gravity maneuvers. The main experimental apparatus consisted of a small drum containing granular material which was rotated slowly while the angle assumed by the slip surface with respect to the horizontal was observed and recorded photographically. Conventional wisdom has held that this 'dynamic angle of response' was a material constant, independent of (among other things) gravitational level. The results presented here are quite contrary, suggesting instead an angle that varies with the reciprocal of the square root of gravity. This finding may have important consequences on the understanding of many active processes in Planetary Geology involving granular materials and may provide qualitative confirmation of some of the theoretical predictions of modern models of granular shear flows.

White, B. R.↗
NASA NTRS1987

Directional solidification of flake and spheroidal graphite cast iron in low and normal gravity environment

A NASA KC-135 research aircraft, flying repeated low-g trajectories that yield 20-30 sec of 0.1-0.001 g microgravity, has been used to study microgravity solidification's elimination of sedimentation and convection (with formation of unique and advantageous microstructures) for the case of eutectic-composition cast irons. The solidification interface of hypereutectic flake and spheroidal graphite cast irons has been slowly advanced through a 4 mm-diameter rod sample. Sample solidification rates have been correlated with accelerometer data, while independently controlling thermal gradients and solidification rates.

Hendrix, J. C.↗