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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Acoustic levitation and manipulation for space applications

A wide spectrum of experiments to be performed in space in a microgravity environment require levitation and manipulation of liquid or molten samples. A novel acoustic method has been developed at JPL for controlling liquid samples without physical contacts. This method utilizes the static pressure generated by three orthogonal acoustic standing waves excited within an enclosure. Furthermore, this method will allow the sample to be rotated and/or oscillated by modifying the phase angles and/or the amplitude of the acoustic field. This technique has been proven both in our laboratory and in a microgravity environment provided by KC-135 flights. Samples placed within our chamber driven at (1,0,0), (0,1,0), and (0,0,1), modes were indeed levitated, rotated, and oscillated.

Wang, T. G.↗
NASA NTRS1980

Optical measurements and tests performed in a low-gravity environment

Shadowgraph and schlieren techniques have been used on board the NASA KC-135 low-gravity simulation aircraft to measure gravity-related fluid flow occurring in various experimental configurations. These configurations included cooled and solidified ammonium chloride and water, electrodeposited cobalt in CoSO4 solution, and immiscible and crystal melt solutions. Hardware tests have also been performed for such critical optical system components as lasers and spatial filters to determine their performance and operation under low-gravity conditions. These test results will be used in the design of the various future Shuttle experiments which will utilize advanced optical measurement techniques. The design and configuration of the optical systems used to make these measurements and tests are presented, and the performance and operation of these systems and their components under low-gravity conditions are discussed. Some preliminary results are included.

Owen, R. B.↗
NASA NTRS1981

Measurement of forces due to liquid motion in a propellant tank

This paper presents the results of a study to develop an analytical model capable of predicting the forces acting on a tank caused by large-amplitude propellant motion. This effort contributed to an analysis of the influence of propellant dynamics on separation of the External Tank from the space shuttle orbiter. This paper is concerned with an experimental investigation that aided in development and verification of the analytical model. A scaling approach was developed that allowed the liquid motion to be simulated in subscale tanks. Liquid reorientation forces were measured using two test systems. One operated in the low-gravity environment produced in a drop tower and the second operated aboard the KC-135 'zero-g' test aircraft. The manner of liquid motion, influence of various factors, and the measured forces are discussed.

Tegart, J. R.↗
NASA NTRS1981

Laser shadowgraph and schlieren studies of gravity-related flow during solidification

Shadowgraph and schlieren techniques were used to observe gravity-related flow arising during solidification. The purpose of these studies was to elucidate the results of previous low gravity solidification experiments. Shadowgraph and schlieren techniques were selected as most suitable for operation in the anticipated experimental environment. A laser shadowgraph/schlieren system was built and flown on KC-135 low gravity simulation flights. A solution of ammonium chloride and water was cooled during the experiment, causing solidification. Growth plumes in the solution were observed and photographed using shadowgraph and schlieren techniques. Results are presented and related to previous work.

Owen, R. B.↗
NASA NTRS1981

Report on research and technology-FY 1981

More than 65 technical reports, papers, and articles published by personnel and contractors at the Dryden Flight Research Center are listed. Activities performed for the Offices of Aeronautics and Space Technology, Space and Terrestrial Applications, Space Transportation Systems, and Space Tracking and Data Systems are summarized. Preliminary stability and control derivatives were determined for the shuttle orbiter at hypersonic speeds from the data obtained at reentry. The shuttle tile tests, spin research vehicle nose shapes flight investigations, envelope expansion flights for the Ames tilt rotor research aircraft, and the AD-1 oblique wing programs were completed as well as the KC-135 winglet program.

Source record↗
NASA NTRS1981

Capillary priming characteristics of a dual passage heat pipe in zero-g

Technical improvements of a long life heat rejection system, suitable for long duration high power missions, that can be constructed and deployed in orbit is discussed. A mathematical model is formulated and a computer program developed which describes the transient priming characteristics of a dual passage heat pipe. An experimental test package is described for flight in the KC-135 Zero-g Aircraft, to be used to verify the modeling predictions.

Peterson, G. P.↗
NASA NTRS1982

Electrodeposition in microgravity: Ground-based experiments

Electrodeposition was studied at one-hundreth g and compared with bench studies at 1 g. The low gravity was achieved during KC-135 aircraft parobolic flights. Flow in a simple cobalt cell (1 M CoSO4) operating under typical commercial conditions (10 to 20 mA/sq cm and 1 V) was monitored with a Schlieren optical system. Natural convection was absent at one-hundreth g. Quantitative comparisons on a cobalt cell with shielded electrodes using interferometry were carried out. Fringe shift differences indicate greater semi-infinite linear diffusion at 1 g than at one-hundreth g for cobalt. Since a shielded electrode operates under diffusion controlled conditions, no differences between 1 g and one-hundreth g would be expected. Similar comparisons on a shielded electrode copper cell were inconclusive. Bench codeposition experiments using polystyrene neutral buoyancy particles coupled with a shielded electrode cobalt cell were begun. Tracking of 12 micron particles showed no measurable difference between thermal/Brownian motion when the cell was operational or nonoperational. Initial experiments on codeposition quality showed a strong dependence upon cathode surface preparation in a shielded electrode configuration.

Riley, C.↗
NASA NTRS1982

Advanced turboprop testbed systems study. Volume 1: Testbed program objectives and priorities, drive system and aircraft design studies, evaluation and recommendations and wind tunnel test plans

The establishment of propfan technology readiness was determined and candidate drive systems for propfan application were identified. Candidate testbed aircraft were investigated for testbed aircraft suitability and four aircraft selected as possible propfan testbed vehicles. An evaluation of the four candidates was performed and the Boeing KC-135A and the Gulfstream American Gulfstream II recommended as the most suitable aircraft for test application. Conceptual designs of the two recommended aircraft were performed and cost and schedule data for the entire testbed program were generated. The program total cost was estimated and a wind tunnel program cost and schedule is generated in support of the testbed program.

Bradley, E. S.↗
NASA NTRS1981

The Development and Use of a Computer-Interactive Data Acquisition and Display System in a Flight Environment

The flight test data requirements at the NASA Dryden Flight Research Center increased in complexity, and more advanced instrumentation became necessary to accomplish mission goals. This paper describes the way in which an airborne computer was used to perform real-time calculations on critical flight test parameters during a flight test on a winglet-equipped KC-135A aircraft. With the computer, an airborne flight test engineer can select any sensor for airborne display in several formats, including engineering units. The computer is able to not only calculate values derived from the sensor outputs but also to interact with the data acquisition system. It can change the data cycle format and data rate, and even insert the derived values into the pulse code modulation (PCM) bit stream for recording.

Computer Systems↗
NASA NTRS1982

Micromechanical model for fibrous ceramic bodies

A micromechanical model is presented to relate the mechanical properties of low-density fibrous ceramic bodies to their microstructures and the properties of the fibers. It is found that properties such as the elastic moduli, fracture toughness, and strength depend on the fiber spacing. In particular, it is shown that the critical stress intensity (Kc) depends on the density of the body with respect to the fiber density, the degree of preferred orientation, the fiber strength, and the fiber radius, suggesting ways of increasing K(c). Furthermore, it is predicted that K(c) will be related to the sonic velocity in the material, reflecting variations in the degree of preferred orientation. The model is found to be consistent with the experimental observations on a silica-based fibrous ceramic, which is being used in the thermal protection system of the Space Shuttle.

Green, D. J.↗
NASA NTRS1982

Interferometry and holography in a low-gravity environment

The groundwork for the use of advanced optical measurement techniques in Space Shuttle materials processing in space (MPS) experiments is being laid in tests, conducted aboard a NASA KC-135 aircraft flying a parabolic trajectory, involving a Mach-Zehnder interferometer and a sideband holographic unit. The two experiments described are (1) the observation of flow during solidification, in which fluid concentration and temperature profiles were measured during unidirectional solidification of a saturated NH4Cl-H2O solution, and (2) the observation of electrodeposition flow, in which interferometry is used to provide quantitative data required in the understanding of electrochemical process transport properties. The free-floating holographic unit was operated in the microgravity environment to both test the practicality of optical systems in such conditions and test the shock and vibration characteristics of the package.

Owen, R. B.↗
NASA NTRS1983

Optical observations of unidirectional solidification in microgravity

Optical interferometric, shadowgraph, and streak photographic methods are used to obtain temperature profiles, concentration gradients, and fluid velocities in NH4Cl-H2O metal-model solution during unidirectional solidification in microgravity. This study elucidates earlier low gravity suborbital rocket experiments and lays the groundwork for space shuttle experiments. The design and operation of the optical units are presented, and results are detailed to ground based experiments. The low gravity experiments were conducted using a KC-135 aircraft flying a parabolic trajectory.

Johnston, M. H.↗
NASA NTRS1983

Analysis and test for space shuttle propellant dynamics

This report presents the results of a study to develop an analytical model capable of predicting the dynamic interaction forces on the Shuttle External Tank, due to large amplitude propellant slosh during RTLS separation. The report details low-g drop tower and KC-135 test programs that were conducted to investigate propellant reorientation during RTLS. In addition, the development of a nonlinear finite element slosh model (LAMPS2, two dimensional, and one LAMPS3, three dimensional) is presented. Correlation between the model and test data is presented as a verification of the modeling approach.

Berry, R. L.↗
NASA NTRS1982

Fracture mechanics in fiber reinforced composite materials, taking as examples B/A1 and CRFP

The validity of linear elastic fracture mechanics and other fracture criteria was investigated with laminates of boron fiber reinforced aluminum (R/A1) and of carbon fiber reinforced epoxide (CFRP). Cracks are assessed by fracture strength Kc or Kmax (critical or maximum value of the stress intensity factor). The Whitney and Nuismer point stress criterion and average stress criterion often show that Kmax of fiber composite materials increases with increasing crack length; however, for R/A1 and CFRP the curve showing fracture strength as a function of crack length is only applicable in a small domain. For R/A1, the reason is clearly the extension of the plastic zone (or the damage zone n the case of CFRP) which cannot be described with a stress intensity factor.

Peters, P. W. M.↗
NASA NTRS1983

Fracture toughness/Young's modulus correlation for low-density fibrous silica bodies

Fracture toughness and static Young's modulus were measured for the low-density silic fiber materials used as tiles in the thermal protection system of the Space Shuttle. The fracture behavior was found to be in excellent agreement with a previously formulated micromechanical model and allowed both (density) classes of tile material to be correlated to a single function. A similar correlation was also found between strength and Young's modulus, which is the basis of a nondestructive evaluation test for these materials. It was shown that the value of Young's modulus determined from a dynamic test can be substantially greater than that determined in a static mechanical test. This effect must be taken into account in the correlation. Finally, it was also determined that these materials have significant variations in Kc, both within and between production units, so that the strength variability in these materials is dependent on both fracture toughness and flaw-size variations.

Green, D. J.↗
NASA NTRS1982

Application of microgravity and containerless environments to the investigation of fusion target fabrication technology

After the first observation of the core-centering force within a liquid shell in the KC-135 flight experiment, this force was successfully reproduced in terrestrial laboratories using two experimental techniques. The core-centering force generated for a compound drop system in the neutral buoyancy tank provides the first correlation between theoretical and experimental results. When this force was generated in a more realistic fusion-pellet system using the focusing-radiator levitating system, it was shown that this is a very strong force indeed in view of the fact that the ratio of specific gravities between the water and the core is approximately five. It is believed that this centering force will contribute significantly to an overall understanding of the fabrication physics of a fusion target system. Results from experiments in a vertical drag-free wind tunnel and in a 16-ft low pressure drop furnace suggest that eliminating or reducing the aerodynamic drag on fusion pellets during their formation stage will prevent the decentering of the bubble. Metallic and metallic glass fusion targets are seen as holding promise for improving and simplifying the fabrication process for ablative-type fusion targets.

Lee, M. C.↗
NASA NTRS1982

Low gravity solidification structures in the tin-15 wt pct lead and tin-3 wt pct bismuth alloys

The tin-15 wt pct lead and tin-3 wt pct bismuth alloys have been solidified in the low-gravity environment provided by the Space Processing Applications Rocket (SPAR), on the KC-135 airplane, and at high 'g' levels in a centrifuge furnace. In each case the resultant cast structure was significantly different from that obtained in ground based experiments. Earlier low-gravity studies with the metal-model system NH4Cl-H2O presaged these results. This paper presents and discusses the influence of changes in the gravity force on the grain structure of these materials.

Johnston, M. H.↗
NASA NTRS1983

Low gravity experiment for studying a rotating fluid having a free surface

Electrical, mechanical, and operational aspects of a test cell assembly for studying rotating fluids with a free surface are described. Results of a stress analysis prepared to document the structural adequacy for safe use on the KC-135 aircraft are presented along with results of a single load proof test of the most critical load case. Engineering drawings are included.

Holderer, O. C.↗