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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

Combustion of porous solids at reduced gravitational conditions

A ground-based experimental and analytic study considered the utility and the feasibility of a space shuttle-based experimental study of the combustion poroussolids at reduced gravitational conditions. This ground-based study employed the Lewis Research Center's g = 0 (drop tower) facility. Experimental g = 1 studies were performed both at the Lewis Research Center and at State University of New York at Stony Brook. It is found that the considered space shuttle-based experimental program is expected to yield vital fundamental combustion information that is not obtainable from earth-bound studies alone. The considered space shuttle-based study is entirely feasible and a detailed approach to these experiments is presented.

Berlad, A. L.↗
NASA NTRS1979

Performance of a capillary propellant management device with hydrazine

The propellant management device that was successfully used in the Viking Orbiter spacecraft was selected for the main propulsion system of the Teleoperator Retrieval System (TRS). Due to differences in the missions and different propellants, the operation of this sheet metal vane device required reverification for the TRS application. An analytical investigation was performed considering the adverse acceleration environment and the high contract angle of the hydrazine propellant. Drop tower tests demonstrated that the device would provide propellant acquisition while the TRS was docked with Skylab, but its operation would have to be supplemented through propellant settling when free-flying.

Tegart, J. R.↗
NASA NTRS1979

Marangoni bubble motion in zero gravity

It was shown experimentally that the Marangoni phenomenon is a primary mechanism for the movement of a gas bubble in a nonisothermal liquid in a low gravity environment. A mathematical model consisting of the Navier-Stokes and thermal energy equations, together with the appropriate boundary conditions for both media, is presented. Parameter perturbation theory is used to solve this boundary value problem; the expansion parameter is the Marangoni number. The zeroth, first, and second order approximations for the velocity, temperature and pressure distributions in the liquid and in the bubble, and the deformation and terminal velocity of the bubble are determined. Experimental zero gravity data for a nitrogen bubble in ethylene glycol, ethanol, and silicone oil subjected to a linear temperature gradient were obtained using the NASA Lewis zero gravity drop tower. Comparison of the zeroth order analytical results for the bubble terminal velocity showed good agreement with the experimental measurements. The first and second order solutions for the bubble deformation and bubble terminal velocity are valid for liquids having Prandtl numbers on the order of one, but there is a lack of appropriate data to test the theory fully.

Thompson, R. L.↗
NASA NTRS1981

Combustion of solid carbon rods in zero and normal gravity

In order to investigate the mechanism of carbon combustion and to assess the importance of gravitational induced convection on the process, zero and normal gravity experiments were conducted in which spectroscopic carbon rods were resistance ignitied and burned in dry oxygen environments. In the zero-gravity drop tower tests, a blue flame surrounded the rod, showing that a gas phase reaction in which carbon monoxide was oxidized to carbon dioxide was taking place. The ratio of flame diameter to rod diameter was obtained as a function of time. It was found that this ratio was inversely proportional to both the oxygen pressure and the rod diameter. In the normal gravity tests, direct mass spectrometric sampling was used to measure gas phase concentrations. The gas sampling probe was positioned near the circumference of a horizontally mounted 0.615 cm diameter carbon rod, either at the top or at angles of 45 deg to 90 deg from the top, and yielded concentration profiles of CO2, CO, and O2 as a function of distance from the surface. The mechanism controlling the combustion process was found to change from chemical process control at the 90 deg and 45 deg probe positions to mass transfer control at the 0 deg probe position at the top of the rod. Under the experimental conditions used, carbon combustion was characterized by two surface reactions, 2C + O2 yields 2CO and CO2 + C yields 2CO, and a gas phase reaction, 2CO + O2 yields 2CO2.

Spuckler, C. M.↗
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

Overview study of combustion experiments in a space laboratory

A program of reduced gravity fluids research was initiated in the late 1950s. The primary motivations for this program was a need to characterize the behavior of propellants in a space environment. In the conduction of experiments, use was made of drop towers, aircraft, and ballistic rockets. There remained a core of problems which could not be solved with the aid of the employed approaches. Proposals for Spacelab experiments were, therefore, submitted. A committee came to the overall conclusion that there was a broad range of combustion experimentation that should be conducted in space. An examination of the analytical models which exist for numerous combustion phenomena reveals that these, are 'zero-G' theories. Experimentation in space will permit these theories to be tested and establish a firm basis upon which to build an understanding of more complicated combustion processes. Realistic in-space fire safety criteria are needed to eliminate the risk of major fire hazards in space. Such criteria can only be obtained through long-term reduced-gravity experimentation.

Cochran, T. 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 NTRS1983

Sphere forming method and apparatus

A system is provided for forming small accurately spherical objects. Preformed largely spherical objects are supported at the opening of a conduit on the update of hot gas emitted from the opening, so the object is in a molten state. The conduit is suddenly jerked away at a downward incline, to allow the molten object to drop in free fall, so that surface tension forms a precise sphere. The conduit portion that has the opening, lies in a moderate vacuum chamber, and the falling sphere passes through the chamber and through a briefly opened valve into a tall drop tower that contains a lower pressure, to allow the sphere to cool without deformation caused by falling through air.

Youngberg, C. L.↗
NASA NTRS1982

Glass shell manufacturing in space

Highly-uniform, hollow glass spheres, which are used for inertial-confinement fusion targets, are formed from metal-organic gel powder feedstock in a drop-tower furnace. The modelling of this gel-to-sphere transformation has consisted of three phases: gel thermochemistry, furnance-to-gel heat transfer, and gravity-driven degradation of the concentricity of the molten shell. The heat transfer from the furnace to the free-falling gel particle was modelled with forced convection. The gel mass, dimensions, and specific heat as well as furnace temperature profile and furnace gas conductivity, were controlled variables. This model has been experimentally verified. In the third phase, a mathematical model was developed to describe the gravity-driven degradation of concentricity in molten glass shells.

Nolen, R. L.↗
NASA NTRS1983

Containerless processing technology

A partial description of the technology, hardware, and facilities developed by NASA in support of space-based containerless processing experiments in the early 1970s is presented, along with recent results. Supercooling was necessary, at a rate of 500 K over a 400 ft span, in early drop tower and molten sample experiments. Placing an electromagnetic levitation coil/chamber at the top of the tube avoided contamination of the sample by guide wires. Recent tests have been performed in attempts to produce metastable bulk A-15 Nb3Ge. The use of copper coils for levitation is suspected to have induced stirring motions in samples. Aerodynamic levitation, needed for nonconducting materials, has been employed to process glass beads at temperatures over 1000 K. An electromagnetic levitation device used to process a gram of BeO on a sounding rocket flight will be carried on a Shuttle flight, as will an acoustic suspension system.

Oran, W. A.↗
NASA NTRS1986

Separation in Binary Alloys

Studies of monotectic alloys and alloy analogs reviewed. Report surveys research on liquid/liquid and solid/liquid separation in binary monotectic alloys. Emphasizes separation processes in low gravity, such as in outer space or in free fall in drop towers. Advances in methods of controlling separation in experiments highlighted.

Frazier, D. O.↗
NASA NTRS1985

Containerless Processing of Undercooled Melts

The physical mechanisms controlling liquid undercooling were studied for application to solidification processing methods. The undercooling potential of containerless processing was assessed on droplet samples of high melting temperature metals drop tube and drop tower facilities and in a laboratory-scale apparatus. New insight into nucleation and crystal growth will be obtained in undercooled liquids of high melting temperature iron and nickel-base systems. The processing parameters include melt superheat, droplet size and particle statistics and droplet surface coating. The solidification behavior is determined by thermal analysis and by structural and metallographic characterization.

Perepezko, J. H.↗
NASA NTRS1985

Mass Transport Phenomena Between Bubbles and Dissolved Gases in Liquids Under Reduced Gravity Conditions

The long term objective of the experiment is to observe the dissolution of isolated, immobile gas bubbles of specified size and composition in a solvent liquid of known concentration in the reduced gravity environment of earth orbit. Preliminary bubble dissolution experiment conducted both in the NASA Lewis 2.2 sec drop tower and in normal gravity using SO2 - Toluene system were not completely successful in their objective. The method of gas injection and lack of bubble interface stabiliy experienced due to the extreme solubility of SO in Toluene has the effects of changing the problem from that of bubble dissolution to one of bubble formation stability and subsequent dissolution in a liquid of unknown initial solute concentration. Current work involves further experimentation in order to refine the bubble injection system and to investigate the concept of having a bubble with a critical radius in a state of unstable equilibrium.

Dewitt, K. J.↗
NASA NTRS1985

Fusion Target Technology

In order to produce the high quality spherical shells that are required, three parameters must be controlled accurately: the shell dimensions, shell sphericity and concentricity, and the surface topology of the shell. Attempts to conduct experiments on the dynamics of liquid bubbles (molten shells) in laboratories are limited by a strong coupling among the three parameters, time, gravity, and temperature. These limitations are circumvented and detailed study of each of the important processes is carried out through the use of low gravity environments collectively available in drop towers, in KC-135 flights, in a neutrally buoyant immiscible system, and in an acoustic levitation system.

Wang, T. G.↗
NASA NTRS1985

Particle Cloud Combustion Experiment

Preparation of flight experiment designs is supported by experimental studies of acoustically induced mixing process, optical transmissivities of particle cloud distributions, wall saturation effects and their control through the use of electrically neutral flame tube materials and surfaces, and the pyrolysis-vaporization kinetics of selected organic particulates. Drop tower tests of stabilized particle cloud flames have allowed valuable comparison of g = 0 and g = 1 (upwards and downwards) stabilized flame propagation. These stabilized flame data will be valuable assists in dealing with the freely propagating particle cloud flame data anticipated through Space Shuttle experimentation. Supporting theoretical studies emphasize comprehensive flame propagation and extinction relations among premixed single phase (gaseous) flames and premixed particle cloud flames, for both stabilized and freely propagating flames.

Berlad, A. L.↗
NASA NTRS1985

Development of Materials Processing Systems for Use in Space on Low-g Simulation Devices

Advanced furnace systems are being developed for use in space. Systems are being tested for current experiment applications and modified for future experiment requirements. Future projects are: (1) fabrication and testing of the Advanced Automated Directional Solidification Furnace (AADSF) flight hardware; (2) development of a Heat Pipe Furnace (HPF) for use in space. Heat pipes will be tested for space flight qualification in conjunction with the furnace development. The HPF design will be based on the AADSF development and will be of modular design including capabilities of operating with or without heat pipes; and (3) the AADSF furnace will be modified and tested to operate at temperatures up to 1700 C in the heated cavity. This will be accomplished by developing a new hot end heating module and insulation package for the existing AADSF. Refurbishment of the Drop Tower Furnace (DTF) is under way. The DTF can operate at temperatures up to 1700 C. The sample size will be approximately 3/8 in. dia. x 5/8 in. long. Design improvements for the General Purpose Rocket Furnace (GPRF) for use in the Material Experiment Assembly (MEA) are to be accomplished.

Aldrich, B. R.↗
NASA NTRS1986

Review and evaluation of space processing applications

Materials research in space which offers advantages in studying phenomena and preparing materials under conditions which cannot be realized in the gravity field of the Earth is discussed. Many techniques were developed to improve processing systems and reduce the effect of gravitationally induced restrictions. The space-based devices take advantage of a wide range of low-gravity facilities including drop towers and tubes, aircraft and sounding rocket parabolic trajectories, simple materials experiment accommodations in the Space Shuttle, and more complex capabilities in Spacelab. All these systems are used to produce novel materials and to study material processing under unique conditions.

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