Flow field simulation Patent
Wind tunnel method for simulating flow fields around blunt vehicles entering planetary atmospheres without involving high temperatures
Jones, R. A.↗
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Results for “High Temperature Methods”
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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Plasma calcining of pigment particles for thermal control coatings
Method utilizes an RF excited plasma to surface deactivate thermally stable powders at high temperatures. Utilization of this plasma heat treatment at high temperatures can be carried out without grain growth, calcination, or agglomeration.
Farley, E. P.↗
Tungsten-reinforced tantalum
Method is described for producing tungsten-reinforced tantalum, a material possessing the high temperature strength of tungsten and room temperature ductility and weldability of tantalum. This material is produced by bonding together and overlaying structure of tungsten wires with chemical vapor deposited tantalum.
Bacigalupi, R. J.↗
Thermospheric temperature measurement technique.
A method for measurement of temperature in the earth's lower thermosphere from a high-velocity probes is described. An undisturbed atmospheric sample is admitted to the instrument by means of a free molecular flow inlet system of skimmers which avoids surface collisions of the molecules prior to detection. Measurement of the time-of-flight distribution of an initially well-localized group of nitrogen metastable molecular states produced in an open, crossed electron-molecular beam source, yields information on the atmospheric temperature. It is shown that for high vehicle velocities, the time-of-flight distribution of the metastable flux is a sensitive indicator of atmospheric temperature. The temperature measurement precision should be greater than 94% at the 99% confidence level over the range of altitudes from 120-170 km. These precision and altitude range estimates are based on the statistical consideration of the counting rates achieved with a multichannel analyzer using realistic values for system parameters.
Hueser, J. E.↗
The Langley cryogenic high Reynolds number wind-tunnel program
A pilot version of a new type of transonic tunnel was placed in operation in the fall of 1973. In the tunnel the cryogenic method is used to obtain a high Reynolds number. The cryogenic concept employs low temperatures to increase the Reynolds number through reducing the viscous forces rather than increasing the inertia forces. The cryogenic approach offers the desired Reynolds-number increase with no increase in dynamic pressure, and therefore no increase in model loads. A series of aerodynamic experiments have been made in the pilot tunnel to confirm the cryogenic concept at transonic speeds. A brief description is given of the project for a large tunnel which has evolved from the investigations.
Polhamus, E. C.↗
Carbide coated fibers in graphite-aluminum composites
The NASA-supported program at the Los Alamos Scientific Laboratory (LASL) to develop carbon fiber-aluminum matrix composites is described. Chemical vapor deposition (CVD) was used to uniformly deposit thin, smooth, continuous coats of TiC on the fibers of graphite tows. Wet chemical coating of fibers, followed by high-temperature treatment, was also used, but showed little promise as an alternative coating method. Strength measurements on CVD coated fiber tows showed that thin carbide coats can add to fiber strength. The ability of aluminum alloys to wet TiC was successfully demonstrated using TiC-coated graphite surfaces. Pressure-infiltration of TiC- and ZrC-coated fiber tows with aluminum alloys was only partially successful. Experiments were performed to evaluate the effectiveness of carbide coats on carbon as barriers to prevent reaction between alluminum alloys and carbon. Initial results indicate that composites of aluminum and carbide-coated graphite are stable for long periods of time at temperatures near the alloy solidus.
Imprescia, R. J.↗
Fractographic evaluation of creep effects on strain-controlled fatigue-cracking of AISI 304LC and 316 stainless steel
Analysis of high temperature low cycle fatigue of AISI 304LC and 316 stainless steels by the method of strainrange partitioning results in four separate strainrange versus life relationships, depending upon the way in which creep-strain and plastic strain are combined within a cycle. Fractography is used in this investigation of the creep-fatigue interaction associated with these cycles. The PP and PC-cycle fractures were transgranular. The PC-cycle resulted in fewer cycles of initiation and shorter total cyclic life for the same applied inelastic strainrange. The CC-cycle had mixed transgranular and intergranular fracture, fewer cycles of initiation and shorter cycle life than PP or PC. The CP-cycle had fully integranular cracking, and failed in fewer cycles than were required for cracks to initate for PP,PC, and CC.
Oldrieve, R. E.↗
Elastomer-Toughened Polyimide Adhesives
T-Peel strengths of adhesive/Titanium bonds are compared for LARC-13 with and without elastomer additives. Elastomer toughening (incorporation of small amounts of rubber into polymer matrix) has been one of the most successful methods for modifying polymer toughness. Addition polyimides are currently under consideration as high-temperature adhesives for bonding composite materials such as titanium.
St. Clair, A. K.↗
Radiant Heating of Ampoule contents
Ampoule charge heating system exploits spectral properties of blackbody radiation and ampoule material transparency to heat charge to high temperature. Cooling gas prevents softening of outside wall of ampoule. Use of proposed method may be limited by tendency of silica (or any other viteous material) to devitrify on prolonged exposure to temperatures near softening point.
Holland, L. R.↗
Hydrodesulfurization of chlorinized coal
A method of desulfurization is described in which high sulfur coals are desulfurized by low temperature chlorinolysis of coal in liquid media, preferably water, followed by hydrodesulfurization at a temperature above 500 C. The coals are desulfurized to an extent of up to 90% by weight and simultaneously dechlorinated to a chlorine content below 0.1% by weight. The product coals have lower volatiles loss, lower oxygen and nitrogen content and higher fixed carbon than raw coals treated with hydrogen under the same conditions. Heating the chlorinated coal to a temperature above 500 C. in inert gas such as nitrogen results in significantly less desulfurization.
Kalvinskas, J. J.↗
Applications of stereoscopic height computations from dual geosynchronous satellite data/joint NASA-Japan stereo project
Stereoscopic heights of the top of an Oklahoma thunderstorm were computed, finding that high cloud tops are not always characterized by very cold IR temperature. The identical method was also applied to the computation of stereo heights based on GOES West and GMS stereo pairs obtained under the NASA-JAPAN cooperative program. It was found that stereo techniques are extremely useful in understanding the structure of thunderstorms in the United States, as well as that of hurricanes over the South Pacific.
Fujita, T. T.↗
Metallo-organic decomposition films
A summary of metallo-organic deposition (MOD) films for solar cells was presented. The MOD materials are metal ions compounded with organic radicals. The technology is evolving quickly for solar cell metallization. Silver compounds, especially silver neodecanoate, were developed which can be applied by thick-film screening, ink-jet printing, spin-on, spray, or dip methods. Some of the advantages of MOD are: high uniform metal content, lower firing temperatures, decomposition without leaving a carbon deposit or toxic materials, and a film that is stable under ambient conditions. Molecular design criteria were explained along with compounds formulated to date, and the accompanying reactions for these compounds. Phase stability and the other experimental and analytic results of MOD films were presented.
Gallagher, B. D.↗
In situ observation of mono-molecular growth steps on aqueous solution grown crystals and the transport of molecules to the crystals
Direct in situ observation of mono-molecular growth steps on a crystal growing in an aqueous solution became possible. The combination of this method with high resolution Schlieren methods or interferometry, permits the growth mechanism of crystals to be investigated directly. Since the observation of growth steps on crystals is the most direct and sensitive way for investigating a crystal growth mechanism, it would contribute to revealing fundamental differences between the growth in space and on Earth. The method was recently extended to in situ observation of the growth processes at high temperatures (1800K).
Tsukamoto, Katsuo↗
Civil propulsion technology for the next twenty-five years
The next twenty-five years will see major advances in civil propulsion technology that will result in completely new aircraft systems for domestic, international, commuter and high-speed transports. These aircraft will include advanced aerodynamic, structural, and avionic technologies resulting in major new system capabilities and economic improvements. Propulsion technologies will include high-speed turboprops in the near term, very high bypass ratio turbofans, high efficiency small engines and advanced cycles utilizing high temperature materials for high-speed propulsion. Key fundamental enabling technologies include increased temperature capability and advanced design methods. Increased temperature capability will be based on improved composite materials such as metal matrix, intermetallics, ceramics, and carbon/carbon as well as advanced heat transfer techniques. Advanced design methods will make use of advances in internal computational fluid mechanics, reacting flow computation, computational structural mechanics and computational chemistry. The combination of advanced enabling technologies, new propulsion concepts and advanced control approaches will provide major improvements in civil aircraft.
Rosen, Robert↗
Sintered Fiber Electrodes
Method proposed to make improved porous electrodes for oxygen pumps, oxygen sensors, high-temperature solid-electrolyte fuel cells, and high-temperature solid-electrolyte electrolysis cells. Electrode made by sintering mat of conducting fibers. Many sintered bonds between intersecting fibers increase electrical conductivity and provide strength, yet allow mat to remain highly porous.
Schroeder, James E.↗
Ability of the total strain version of strainrange partitioning to characterize thermomechanical fatigue behavior
Strainrange partitioning (SRP) was originally developed on an inelastic strain basis for isothermal fatigue in the high-strain regime where the inelastic strainrange could be determined accurately. However, most power-generating equipment operates in the regime where the inelastic strains are small and difficult to determine with any degree of accuracy. This shortcoming led to the development of the total strain version of SRP (TS-SRP). Power-generating equipment seldom operates under isothermal conditions, and isothermal life prediction methods cannot be depended on to predict the lives of anisothermal cycles. To overcome this shortcoming, a method was proposed for extending TS-SRP to characterize anisothermal fatigue behavior and to predict the lives of thermomechanical fatigue (TMF) cycles using apppropriate anisothermal data. The viability of this method, referred to as TMF/TS-SRP, was demonstrated using TMF data for two high-temperature aerospace alloys. In this report, data from the literature are used to examine the ability of TMF/TS-SRP to characterize the failure and flow behavior of three low-strength, high-ductility alloys widely used for ground-based power-generating equipment. The three alloys are type 304 stainless steel, 1Cr-1Mo-0.25V steel, and 2.25Cr-1Mo steel. Because of the limited nature of the data, it was possible to evaluate the characterization, but not the predictive capability of TMF/TS-SRP.
Saltsman, James F.↗
Metallurgical coatings and thin films; Proceedings of the International Conference, 18th, San Diego, CA, Apr. 22-26, 1991. Vols. 1 & 2
A conference on metallurgical coatings and thin films produced papers in the areas of coatings for use at high temperatures; hard coatings and deposition technologies; diamonds and related materials; tribological coatings/surface modifications; thin films for microelectronics and high temperature superconductors; optical coatings, film characterization, magneto-optics, and guided waves; and methods for characterizing films and modified surfaces.
Mcguire, Gary E.↗
Measurement of the Heat Capacity of He-II Under a Heat Current Near the Lambda Transition
We present preliminary measurements of the heat capacity of superfluid helium-4 under an applied heat current near the lambda transition. The calorimeter is a standard cylindrical thermal conductivity cell with a 0.6 mm gap between two copper endplates. The sidewall is made of stainless steel. A heat current density in the range of 1 to 4 microW/sq cm is applied through the helium sample while a pulse method is used to measure the heat capacity. Temperature changes are recorded with high-resolution thermometers (HRTs) located on the top and bottom endplates. Corrections are made to the readings of the HRTs to account for the Kapitza boundary resistance and the anomalous Kapitza boundary resistance. After the corrections, both the top and the bottom HRTs. give the same heat capacity values. The heat capacity is found to be much larger than the prediction of recent theories. We also plotted our data on a scaled plot to test the prediction of scaling by the theories. The result and its interpretation will be presented. The cell height was deliberately made to be thin to reduce the effects of gravity. Nonetheless, gravity is expected to have significant effects on the heat capacity data in the temperature range of our measurement. A space experiment would remove this unwanted gravity effect and allow the true physics to be examined. Moreover, in the absence of gravity, a deeper cell can be used allowing HRTs to be mounted on to the sidewall providing direct measurements of the helium temperature, unaffected by the anomalous Kapitza boundary resistance.
Harter, Alexa W.↗