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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Permeation Resistance of Chlorinated Polyethylene Against Hydrazine Fuels

The permeation resistance of chlorinated polyethylene (CPE) used in chemical protective clothing against the aerospace fuels hydrazine, monomethylhydrazine (MMH), and uns-dimethylhydrazine (UDMH) was determined by measuring breakthrough times and time-averaged vapor transmission rates using an ASTM F 739 permeation cell. Two exposure scenarios were simulated: a 2 hour (h) fuel vapor exposure, and a liquid fuel "splash" followed by a 2 h vapor exposure. To simulate internal suit pressure during operation, a positive differential pressure of 0.3 in. water (75 Pa) on the collection side of the permeation apparatus was used. Breakthrough was observed after exposure to liquid MMH, and to vapor and liquid UDMH. No breakthrough was observed after exposure to vapor and liquid hydrazine, or vapor MMH. A model was then used to calculate propellant concentrations inside a totally encapsulating chemical protective suit based on the ASTM permeation data obtained in the present study. Concentrations were calculated under conditions of fixed vapor transmission rate, variable breathing air flow rate, and variable splash exposure area. Calculations showed that the maximum allowable permeation rates of hydrazine fuels through CPE were of the order of 0.05 to 0.08 ng sq cm/min for encapsulating suits with low breathing air flow rates (of the order of 5 scfm or 140 L/min). Above these permeation rates, the 10 parts per billion (ppb) threshold limit value time - weighted average could be exceeded for chemical protective suits having a CPE torso. To evaluate suit performance at ppb level concentrations, use of a sensitive analytical method such as cation exchange high performance liquid chromatography with amperometric detection was found to be essential.

Waller, J. M.↗
NASA NTRS2016

Climate Analytics as a Service

Exascale computing, big data, and cloud computing are driving the evolution of large-scale information systems toward a model of data-proximal analysis. In response, we are developing a concept of climate analytics as a service (CAaaS) that represents a convergence of data analytics and archive management. With this approach, high-performance compute-storage implemented as an analytic system is part of a dynamic archive comprising both static and computationally realized objects. It is a system whose capabilities are framed as behaviors over a static data collection, but where queries cause results to be created, not found and retrieved. Those results can be the product of a complex analysis, but, importantly, they also can be tailored responses to the simplest of requests. NASA's MERRA Analytic Service and associated Climate Data Services API provide a real-world example of climate analytics delivered as a service in this way. Our experiences reveal several advantages to this approach, not the least of which is orders-of-magnitude time reduction in the data assembly task common to many scientific workflows.

big data↗
NASA NTRSDate not supplied

AAM NC ATI TechTalk - Aerograph Architecture v1

Aerograph is NASA’s data management system for Advanced Air Mobility. Its mission is to support AAM research by providing a reliable and secure system that collects, stores, protects, and shares AAM data. Its vision is to provide a system that AAM research scientists, aerospace engineers, data scientists, and analysts trust for obtaining NC data and performing key analyses. The types of data Aerograph manages involves data related to flight test events, including: Aircraft Performance and Characterization (e.g., position reports) Airspace (e.g., operation intent, waypoints, and constraints) Environment (e.g., surface and wind weather) Infrastructure (e.g., surveillance coverage) Derivative Analytical Artifacts (e.g., glide path performance chart, 3D position chart, Integrated Data Product)

Aerograph↗
NASA NTRS1968

Propulsive re-entry aerodynamics Interim report, 1 Jun. 1967 - 1 Jun. 1968

This report discusses the progress accomplished during the first year of a two-year contract to study Propulsive Re-Entry Aerodynamics. Analytical methods were developed during the first year to predict the flow field in the immediate vicinity of a planetary entry system composed of an aeroshell with a single retrorocket which exhausts into a subsonic or supersonic counterflowing planetary atmosphere. In the second year a digital computer program will be developed for the analytical solutions, and the analytical model will be tested by performing an experimental test program and comparing the experimental results with the analytical predictions. The analytical investigation considers the flow field due to a single supersonic retrorocket exhausting from an aeroshell into oncoming subsonic, transonic, or supersonic streams in the large thrusting coefficient regime, 0.5 < C(sub T) = T/q(sub ∞) A(sub m) < 15, which is the range of thrusting coefficients encountered during the terminal landing phase for planetary landing on Mars or Venus. Analyses are provided for all the geometrical features of the flow field such as the location of the terminal shock, jet boundary, and the profile for the interface between the jet and atmospheric gases. In addition, analyses are developed which describe the growth of the mixing layers along the interface and at the edge of the jet boundary and dead-air region and the reattachment of the shear layer to the aeroshell or the recompression of the shear layer in wake type flow. A comprehensive discussion of the experimental wind tunnel test program to be accomplished in Phase II is presented.

Philip O Jarvinen↗
NASA NTRS1970

Mechanism of operation of the TFE-bonded gas-diffusion electrode

Mathematical analytical model predicts the performance of an electrode as a function of certain measurable physical characteristics. Concept assumes the catalyst particles form porous electrically conductive agglomerates which are completely flooded with electrolyte.

Giner, J.↗
NASA NTRS1972

Apollo experience report: Thermal design of Apollo lunar surface experiments package

The evolution of the thermal design of the Apollo lunar surface experiments package central station from the basic concept to the final flight hardware is discussed, including results of development, prototype, and qualification tests that were used to verify that the flight hardware would operate adequately on the lunar surface. In addition, brief discussions of the thermal design of experiments included in the experiments package are presented. The flight thermal performance is compared with analytical results and thermal-vacuum test results, and design modifications for future lunar surface experiment packages are presented.

Harris, R. S., Jr.↗
NASA NTRS1972

Conical-reflector antennas.

The mechanical advantages of a singly curved conical reflector are demonstrated by the experimental test of a furlable 1.83 m conical-Gregorian antenna at 16.33 GHz. The measured gain of 47.5 dB corresponds to a net efficiency of over 57%. A ray-optics analysis of conical-reflector antennas is presented, and data useful in the design of conical antennas are given. The conical-Gregorian antenna, in which a subreflector is used in conjunction with a conventional horn feed, is considered in detail. A physical-optics analysis of the conical-Gregorian antenna is used to investigate diffraction and other effects, and to analytically confirm the high performance of the antenna.

Ludwig, A. C.↗
NASA NTRS1973

Experimental verification of computer spray-combustion models

Analytical model formulation, representing performance of spray-combustion device, is based on understanding of atomization, mixing, vaporization, and combustion which occurs in device. Report lists results of correlations of computed values with values obtained from experiments with rocket combustor. Technique offers excellent method for evaluating validity and ranges of applicability of combustion models.

Nurick, W. H.↗
NASA NTRS1972

A study of multiplex data bus techniques for the space shuttle

A comprehensive technology base for the design of a multiplexed data bus subsystem is provided. Extensive analyses, both analytical and empirical, were performed. Subjects covered are classified under the following headings: requirements identification and analysis; transmission media studies; signal design and detection studies; synchronization, timing, and control studies; user-subsystem interface studies; operational reliability analyses; design of candidate data bus configurations; and evaluation of candidate data bus designs.

Kearney, R. J.↗
NASA NTRS1973

Analytical and experimental investigation of aircraft metal structures reinforced with filamentary composites. Phase 3: Major component development

Analytical and experimental investigations, performed to establish the feasibility of reinforcing metal aircraft structures with advanced filamentary composites, are reported. Aluminum-boron-epoxy and titanium-boron-epoxy were used in the design and manufacture of three major structural components. The components were representative of subsonic aircraft fuselage and window belt panels and supersonic aircraft compression panels. Both unidirectional and multidirectional reinforcement concepts were employed. Blade penetration, axial compression, and inplane shear tests were conducted. Composite reinforced structural components designed to realistic airframe structural criteria demonstrated the potential for significant weight savings while maintaining strength, stability, and damage containment properties of all metal components designed to meet the same criteria.

Bryson, L. L.↗
NASA NTRS1973

Detonation propulsion for high pressure environments

One limitation encountered by chemical rocket propulsion in high pressure planetary atmospheres is illustrated by the conflict between the dependence of specific impulse on the ratio of chamber pressure to ambient pressure and the dependence of the motor structural design on the difference between the pressures. This work proposes to resolve the difficulty by employing detonating propellant in which the high pressures necessary for efficient propulsion are developed over a short time and need not be contained statically. Experimental results are presented to substantiate this claim of relatively high performance, together with an analytical development that approximately describes the flow dynamics.

Varsi, G.↗
NASA NTRS1975

Fluid manifold design for a solar energy storage tank

A design technique for a fluid manifold for use in a solar energy storage tank is given. This analytical treatment generalizes the fluid equations pertinent to manifold design, giving manifold pressures, velocities, and orifice pressure differentials in terms of appropriate fluid and manifold geometry parameters. Experimental results used to corroborate analytical predictions are presented. These data indicate that variations in discharge coefficients due to variations in orifices can cause deviations between analytical predictions and actual performance values.

Humphries, W. R.↗
NASA NTRS1971

Pressure control and analysis report: Hydrogen Thermal Test Article (HTTA)

Tasks accomplished during the HTTA Program study period included: (1) performance of a literature review to provide system guidelines; (2) development of analytical procedures needed to predict system performance; (3) design and analysis of the HTTA pressurization system considering (a) future utilization of results in the design of a spacecraft maneuvering system propellant package, (b) ease of control and operation, (c) system safety, and (d) hardware cost; and (4) making conclusions and recommendations for systems design.

Source record↗
NASA NTRS1972

Feasibility study of inlet shock stability system of YF-12

The feasibility of self actuating bleed valves as a shock stabilization system in the inlet of the YF-12 is considered for vortex valves, slide valves, and poppet valves. Analytical estimation of valve performance indicates that only the slide and poppet valves located in the inlet cowl can meet the desired steady state stabilizing flows, and of the two the poppet valve is substantially faster in response to dynamic disturbances. The poppet valve is, therefore, selected as the best shock stability system for the YF-12 inlet.

Blausey, G. C.↗
NASA NTRS1976

Convolutional code performance in the Rician fading channel

The performance of short constraint length convolutional codes in conjunction with binary phase-shift keyed (BPSK) modulation and Viterbi maximum likelihood decoding on the classical Rician fading channel is examined in detail. Primary interest is in the bit error probability performance as a function of E sub b/N sub 0 parameterized by the fading channel parameters. Fairly general upper bounds on bit error probability performance in the presence of fading are obtained and compared with simulation results in the two extremes of zero channel memory and infinite channel memory. The efficacy of simple block interleaving in combating the memory of the channel is thoroughly explored. Results include the effects of fading on tracking loop performance and the subsequent impact on overall coded system performance. The approach is analytical where possible; otherwise resort is made to digital computer simulation.

Modestino, J. W.↗
NASA NTRS1976

Nonintrusive Flowmeter

The results of analytical and experimental work performed in the design, fabrication, and test of a prototype nonintrusive gaging system for use in monitoring the consumption of earth-storable fuels and oxidants in either a one-g or a zero-g environment are explained. The design specifications were those applicable to the reaction control system and to the orbital maneuvering system (OMS) fuel and oxidant on the space shuttle while in orbit. The major requirement was for the measurement of flow pulses with sufficient accuracy to provide a continuous knowledge of the fuel and oxidant remaining in the OMS system to within 1% or better. An ultrasonic frequency chirp technique was used having a high inherent rejection for signals traversing stray paths, and for random noise generated by the flowing liquid. A detailed analysis of the frequency chirp approach for two modes of operation (period and phase changes), including an error analysis are reported.

Greene, M. W.↗
NASA NTRS1979

Computer modeling of a two-junction, monolithic cascade solar cell

The theory and design criteria for monolithic, two-junction cascade solar cells are described. The departure from the conventional solar cell analytical method and the reasons for using the integral form of the continuity equations are briefly discussed. The results of design optimization are presented. The energy conversion efficiency that is predicted for the optimized structure is greater than 30% at 300 K, AMO and one sun. The analytical method predicts device performance characteristics as a function of temperature. The range is restricted to 300 to 600 K. While the analysis is capable of determining most of the physical processes occurring in each of the individual layers, only the more significant device performance characteristics are presented.

Lamorte, M. F.↗
NASA NTRS1979

Deployable antenna technology development for the Large Space Systems Technology program

The critical technologies associated with the development of deployable reflector antenna technology for the LSST program will be derived from NASA mission models and the subsequent requirements will be related to the classes of missions involved. The approach formulated for the development of reflector technology is based on the development of specific reflector concepts that have been identified as leading candidates for future applications. The development approach will be augmented by supporting technology disciplines such as controls, materials, electromagnetic analysis, as well as the capability of analytically predicting the overall performance of the large space system.

Freeland, R. E.↗