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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1938

Tests of a Contra-propeller for Aircraft

Tests of an 8-blade contra-propeller of 32-inch diameter in combination with a 4-inch, 36-inch diameter adjustable pitch, metal propeller at pitch setting of 15, 25, 35, and 45 degrees at 0.75 R were made. The tests showed a significant increase in effective thrust of the combination over that of the propeller alone for value V/nD somewhat below those for maximum efficiency and without a corresponding increase of power absorbed. From 1/2 percent to 2-1/2 percent in propulsive efficiency was thus gained in this range. In all but one case, however, the peak propulsive efficiency of the combination was found to be from 1 to 2 percent less than that of the propeller alone. Counter torque on the contra-propeller amounted to about 50 percent of the propeller torque.

Benson, William M↗
NASA NTRS2019

Laser-Enhanced Arc-Jet Facility Wedge Tests: Avcoat Material Performance Under Convective and Radiative Heating Environments

This paper presents the first set of experimental results from Laser Enhanced Arc-Jet Facility (LEAF-Lite) tests that were conducted shortly after the radiative LEAF-Lite system was added to the 60-MW Interaction Heating Facility at NASA Ames Research Center. Results were gathered to characterize the new radiative and combined heating capabilities as well as the convective heating resulting from the new IHF nozzle that was required for combined heating operations. Tests were ultimately conducted at several combinations of radiative and convective heating prompted by the need to understand the effect of combined heating on the Orion heatshield material prior to pursuing combined heating tests of the more complex block architecture.

Laser-Enhanced Arc-Jet Facility↗
NASA NTRS2004

Lithium-Ion Verification Test Program

In order to assess the capabilities of current aerospace lithium-ion cells to perform long-term NASA missions, low-earth-orbits (LEO) testing to evaluate long-term cycle life was initiated. A flexible program was developed at NASA Glenn Research Center to enable assessment of technology developments as they occur as well as provide information about different cell vendors and cell designs. Following extensive characterization testing, cells are tested using LEO charge and discharge profiles under ten different combinations of test conditions that were statistically chosen to determine the effects of depth-of-discharge, temperature, and end-of-charge voltage on LEO cycle life. Four cells from each vendor are tested at each specific combination of conditions. Conditions included in the test matrix are depth-of-discharges of 20%, 30, 35%, and 40%; temperatures of 20, 30, and 40 C; and end-of-charge voltages of 3.85 V, 3.95 V, and 4.05 V. Cells are randomly assigned to packs and packs are randomly assigned to test conditions. The capacity of the cells to 3.0 V at the conditions of the test is being periodically measured. The results of this testing will be used to model cell performance and degradation as a function of test operating conditions. Cells are being evaluated in 4-cell series strings with charge voltage limits being applied to individual cells by charge control units designed and built at NASA Glenn Research Center. Testing is being performed at the Naval Surface Warfare Center/Crane Division in Crane, IN. Testing was initiated in September 2004 with 40 Ah cells from Saft and 30 Ah cells from Lithion. The test program is being expanded with the addition of cells from MSA and the addition of small cell modules is being considered. Preliminary results showing voltage, temperature, usable capacity per unit mass, and voltage dispersion as their changes over time for the cells at 20 C is presented.

McKissock, Barbara↗
NASA NTRS1986

Estimating Wall-Induced Velocities in Wind Tunnels

Estimates of wall effects in two-dimensional wind tunnel obtained using upwash measurements on two contours near test model. Method derived from combination of prior techniques that correct for wall effects. Improved method limited to flows described by linear equations. Method accurately predicted wall-induced velocities along centerline of theoretical wind tunnel and confirmed that wall adjustments substantially reduced wall interference.

Schairer, E. T.↗
NASA NTRS1982

Combined four-wall interference assessment in two-dimensional airfoil tests

Two different procedures are examined for combining the correction method developed by Barnwell and Sewall for the effects of the sidewall boundary layer in two-dimensional wind-tunnel tests with the assessment and correction method due to Kemp for the effects of the upper and lower tunnel walls. One procedure utilizes the similarity transformation defined by Sewall to eliminate velocity perturbations induced by the sidewall boundary layer from consideration in the assessment and correction method as sources of error. The other procedure combines perturbations from all four walls before assessment and correction. In general, the two procedures yield different corrections to Mach number and angle of attack, either of which can be considered valid. Pressure distributions corrected for higher order interference effects are provided by either procedure.

Kemp, W. B., Jr.↗
NASA NTRS1985

Parameter extraction from spaceborne MOSFETs

An addressable matrix of 32 CMOS transistors was designed into a test chip to be flown on the Combined Release and Radiation Effects Satellite (CRRES). In this paper the matrix is described along with a SPICE-like parameter extraction procedure called JMOSFIT, and Cobalt 60 radiation test results are presented that illustrate the shift in the 21-MOSFET parameters derived from JMOSFIT.

Buehler, M. G.↗
NASA NTRS2008

Effect of Pressure on Piloted Ignition Delay of PMMA

In order to reduce the risk of decompression sickness associated with spacewalks, NASA is considering designing the next generation of exploration vehicles and habitats with a different cabin environment than used previously. The proposed environment uses a total cabin pressure of 52.7 to 58.6 kPa with an oxygen concentration of 30 to 34% by volume and was chosen with material flammability in mind. Because materials may burn differently under these conditions and there is little information on how this new environment affects the flammability of the materials onboard, it is important to conduct material flammability experiments at the intended exploration atmosphere. One method to evaluate material flammability is by its ease of ignition. To this end, piloted ignition delay tests were conducted in the Forced Ignition and Spread Test (FIST) apparatus subject to this new environment. In these tests, polymethylmethacylate (PMMA) was exposed to a range of oxidizer flow velocities and externally applied heat fluxes. The ultimate goal is to determine the individual effect of pressure and the combined effect of pressure and oxygen concentration on the ignition delay. Tests were conducted for a baseline case of normal pressure and oxygen concentration, low pressure (58.6 kPa) with normal oxygen (21%). Future work will focus on low pressure with 32% oxygen concentration (space exploration atmosphere - SEA) conditions. It was found that reducing the pressure while keeping the oxygen concentration at 21% reduced the ignition time by 17% on average. It was also noted that the critical heat flux for ignition decreases in low-pressure conditions. Because tests conducted in standard atmospheric conditions will underpredict the flammability of materials intended for use on spacecraft, fire safety onboard at exploration atmospheres may be compromised.

McAllister, Sara↗
NASA NTRS2019

3+2+X: What Is the Most Useful Depolarization Input for Inverting Lidar Measurements of Non-Spherical Particles to Microphysical Properties?

The typical multiwavelength aerosol lidar data set for inversion of optical to microphysical parameters is composed of three backscatter coefficients (β ) at 355, 532, and 1064 nm and two extinction coefficients (α ) at 355 and 532 nm. This data combination is referred to as 3β +2α or 3+2 data set. This set of data is sufficient for retrieving some important microphysical particle parameters if the particles have spherical shape. Here, we investigate the effect of including the particle linear depolarization ratio (δ) as a third input parameter to the inversion of lidar data. The inversion algorithm is generally not used if measurements show values of δ that exceed 0.10 at 532 nm, i.e. in the presence of non-spherical particles such as desert dust, volcanic ash, and under special circumstances biomass-burning smoke.We use experimental data collected with instruments that are capable of measuring δ at all three lidar wavelengths with an inversion routine that uses the theory of light scattering by randomly oriented spheroids to replicate scattering properties of non-spherical particles. This is the first systematic test of the effect of using all theoretically possible combinations of δ taken at 355, 532, and 1064 nm as input in the lidar data inversion. We find that depolarization information at least at one wavelength already provides useful information in the in version of optical data that describe light-scattering by nonspherical particles. However, any choice of δ(λ) will give lower values of the single-scattering albedo than the traditional 3+2 data set. We find that input data sets that include 355 give a non-spherical fraction that closely resembles the dust ratio we obtain from using β(532) and δ(532) in a methodology applied in aerosol-type separation. The use of 355 in data sets of two or three reduces the fraction of non-spherical particles that is retrieved when using δ(532) and δ(1064). Use of the latter two without accounting for 355 generally leads to high fractions of non-spherical particles that we consider not trustworthy. The use of three δ(λ) instead of two δ(λ) including the constraint that one of these is measured at 355 nm does not provide any advantage over using 3+2+δ(355). Because of the technical challenges involved with accurately measuring δ(1064) we conclude that — depending on measurement capability — the future standard input for inversion using spheroid kernels might be 3+2+δ(355) or 3+2+δ(355)+δ(532).

Tesche, M.↗
NASA NTRSDate not supplied

Radiation Effects Considerations for Instrumentation and Control in Space Nuclear Systems

Radiation effects in electrical, electronic, electro-motive, and electro-optical (EEEE) hardware encompass a complex variety of interactions, processes, environments, and an evolving landscape of relevant hardware. Appropriately mitigating the effects of radiation in sensors, data acquisition, and control hardware is among the most significant challenges associated with deploying space nuclear power and propulsion systems. The expertise within EEEE radiation effects disciplines require working knowledge that is at least as complex and diverse as the problem itself, but that should not dissuade stakeholders and engineers in adjacent disciplines from attempting to understand the general principles associated with the problem at hand. This brief overview seeks to bring to the foreground a set of relevant topics that are of special importance for space nuclear propulsion applications that involve high rates of neutron and gamma radiation. The unique set of environments and design requirements for space nuclear systems mean that the experience and utility for methods applied to typical spaceflight hardware or terrestrial nuclear systems must not be applied naively. Forward consideration on the applicability of testing methods applied to either existing or bespoke hardware is likely to drive early decisions on system-wide radiation effects mitigation strategies, and will influence procurement requirements for providers of radiation tolerant hardware who are unlikely to have experience in this unique set of environments. Radiation hardness assurance (RHA) guidance should be adapted and emphasize the importance of hardware testing in the relevant environment. These must consider the combined effects of temperature, total ionizing dose (TID), non-ionizing/displacement damage (TNID/DD), and single event effects (SEE), and should consider the impacts of flux (rate) in addition to cumulative effects.

Radiation↗
NASA NTRS1932

The Effect of Propellers and Nacelles on the Landing Speeds of Tractor Monoplanes

This paper reports wind-tunnel tests giving the lift coefficients of large-scale wing-nacelle combinations both with and without the propeller. The tests were made to show the effect of nacelles, and idling and stopped propellers on the landing speeds of tractor monoplanes. Four types of nacelles with various cowlings were used in numerous positions with respect to both a Clark Y and a thick airfoil. The effect of both the idling and stopped propeller on lift, and consequently on landing speed, was negligible. A nacelle with exposed engine cylinders when placed directly in front of an airfoil caused a slight reduction in lift, consequently an increase in landing speed, over the condition with the wing alone. With this exception no appreciable effect on landing speed was indicated for any of the other combinations.

Windler, Ray↗
NASA NTRS1984

Radiation testing of GaAs on CRRES and LIPS experiment

The radiation damage of solar cells has become a prime concern to the U.S. Air Force due to longer satellite lifetime requirements. Flight experiments were undertaken on the Navy Living Plume Shield (LPS) satellite and the NASA/Air Force Combined Release and Radiation Effects Satellite (CRRES) to complement existing radiation testing. Each experiment, the rationale behind it, and its approach and status are presented. The effect of space radiation on gallium arsenide (GaAs) solar cells was the central parameter investigated. Specifications of the GaAs solar cells are given.

Trumble, T. M.↗
DOE OSTI2025

Effects of Water Vapor on the Reactivity of Aluminosilicates in Vapor-Phase Propanal Aldol Condensation

Aluminosilicate materials have been extensively studied as efficient aldol catalysts for C-C coupling reactions due to their acidic nature, high surface area, thermal stability, and porous structure. This work investigated the impact of water vapor pressure on the catalytic reactivity of aluminosilicates for the aldol condensation of propanal to 2-methyl-2-pentenal (MP). The catalytic performance of amorphous SiO2-Al2O3 (A-Si-Al) and aluminated MCM-41 (Al-MCM-41) for the vapor-phase aldol condensation of propanal was evaluated at 200 degrees C as a function of vapor-phase water content at atmospheric pressure. Our findings demonstrate that co-feeding low water vapor pressures (1-18 kPa) with propanal enhances the rates of MP production at 200 degrees C on A-Si-Al. Conversely, water vapor pressures of 25 kPa result in a decrease in aldol dimer formation rates. The rate of MP production evaluated on Al-MCM-41 also increased in the presence of 5 kPa water compared to anhydrous conditions. Propylamine temperature-programmed desorption analyses revealed an increase in Bronsted acid site density when both catalysts were exposed to water, which likely accounts for the observed enhancement in aldol condensation reactivity under hydrous conditions. Reversibility testing of the water vapor effect under reaction conditions, combined with X-ray diffraction analysis of fresh, spent, and regenerated catalysts, revealed no structural changes in either aluminosilicate upon exposure to water or reaction conditions. The rates of aldol condensation and the impact of water vapor were highly consistent across both materials, suggesting that zeolite crystallinity has minimal influence on the catalytic performance.

acid catalysts↗
NASA NTRS1987

On the spectral reflectance properties of materials exposed at the Viking landing sites

Reflectance data derived from Viking Lander multispectral data were used to characterize the types of soils and blocks exposed at the landing sites and to search for evidence of relatively unaltered igneous rocks. A comprehensive effort was mounted to examine multispectral data that combines testing of camera radiometric calibrations, explicitly removing the effects of atmospheric attenuation and skylight, and quantitatively comparing the corrected data to reflectance data from laboratory materials. Bi-directional reflectances for blue, green and red channels were determined for 31 block and soil exposures at Viking landing sites.

Guinness, E.↗
NASA NTRS1986

An analytical method for predicting CMOS SRAM upsets with application to asymmetrical memory cells

An analytical method was developed to predict the heavy-ion-induced upset rate of static random access memory (SRAM) cells. The method was applied to the design of a memory with asymmetrical cells where the goal was to increase the upset rate in order to increase the number of observed upsets in a space environment. The asymmetry is achieved by increasing the drain area of selected transistors in the cell. Results from the analytical model for a space environment indicate the upset rate for the experimental asymmetrical cell (17.2 upsets/1 kbit-year) will be 4.7 times larger than the upset rate for the minimum-geometry balanced cell (3.6 upsets/1 kbit-year). The asymmetrical SRAM was designed into a test chip intended for the Combined Release and Radiation Effects Satellite (CRRES).

Buehler, Martin G.↗
NASA NTRS2014

Characterization of Encapsulated Corrosion Inhibitors for Environmentally Friendly Smart Coatings

Research efforts are under way to replace current corrosion inhibitors with more environmentally friendly alternatives. However, problems with corrosion inhibition efficiency, coating compatibility and solubility have hindered the use of many of these materials as simple pigment additives.This paper will present technical details on how the Corrosion Technology Lab at NASAs Kennedy Space Center (KSC) has addressed these issues by encapsulating environmentally friendly inhibitors into organic and inorganic microparticles and microcapsules. The synthetic process for polymer particles was characterized and post-synthesis analysis was performed to determine the interactions between the inhibitors and the encapsulation material. The pH-controlled release of inhibitors from various particle formulations in aqueous base was monitored and compared to both electrochemical and salt immersion accelerated corrosion experiment. Furthermore, synergistic corrosion inhibition effects observed during the corrosion testing of several inhibitor combinations will be presented.

Environmentally Friendly↗
NASA NTRS2015

Hazard Assessment from Storm Tides and Rainfall on a Tidal River Estuary

Here, we report on methods and results for a model-based flood hazard assessment we have conducted for the Hudson River from New York City to Troy/Albany at the head of tide. Our recent work showed that neglecting freshwater flows leads to underestimation of peak water levels at up-river sites and neglecting stratification (typical with two-dimensional modeling) leads to underestimation all along the Hudson. As a result, we use a three-dimensional hydrodynamic model and merge streamflows and storm tides from tropical and extratropical cyclones (TCs, ETCs), as well as wet extratropical cyclone (WETC) floods (e.g. freshets, rain-on-snow events). We validate the modeled flood levels and quantify error with comparisons to 76 historical events. A Bayesian statistical method is developed for tropical cyclone streamflows using historical data and consisting in the evaluation of (1) the peak discharge and its pdf as a function of TC characteristics, and (2) the temporal trend of the hydrograph as a function of temporal evolution of the cyclone track, its intensity and the response characteristics of the specific basin. A k-nearest-neighbors method is employed to determine the hydrograph shape. Out of sample validation tests demonstrate the effectiveness of the method. Thus, the combined effects of storm surge and runoff produced by tropical cyclones hitting the New York area can be included in flood hazard assessment. Results for the upper Hudson (Albany) suggest a dominance of WETCs, for the lower Hudson (at New York Harbor) a case where ETCs are dominant for shorter return periods and TCs are more important for longer return periods (over 150 years), and for the middle-Hudson (Poughkeepsie) a mix of all three flood events types is important. However, a possible low-bias for TC flood levels is inferred from a lower importance in the assessment results, versus historical event top-20 lists, and this will be further evaluated as these preliminary methods and results are finalized. Future funded work will quantify the influences of sea level rise and flood adaptation plans (e.g. surge barriers). It would also be valuable to examine how streamflows from tropical cyclones and wet cool-season storms will change, as this factor will dominate at upriver locations.

Hazard assessment↗
NASA NTRS1990

Evaluation of thermal and mechanical loading effects on the structural behavior of a SIC/titanium composite

Composite specimens of titanium-15-3 matrix reinforced with continuous SCS-6 silicon carbide fibers were tested under a variety of thermal and mechanical loadings. A combined experimental/finite element approach was used to estimate the effective in situ modulus of the matrix material and to evaluate changes in modulus due to the applied loads. Several fiber orientations were tested. Results indicate that the effect of thermal loads on composite stiffness varies with fiber orientation. Applications of this method to test specimens damaged by uniaxial tension, thermal cycling, and isothermal fatigue loadings are used to illustrate that by monitoring overall structural behavior, changes in stiffness caused by thermomechanical loading can be detected.

Grady, J. E.↗
NASA NTRS1990

Differential effects of scopolamine and amphetamine on microcomputer-based performance tests

The effects of four weekly treatments with scopolamine (1.0 mg) and d-amphetamine (10 mg), separately or in combination, on human performance were investigated in 16 subjects undergoing nine performance tests from a menu of microcomputer-based tests administered after the treatment. It was d-amphetamine treatment that enhanced the results of motor and perceptual speed tests, while scopolamine had no effect on these tests. Two of the five cognitive tests showed reductions with scopolamine. The effects of scopolamine in this and other studies are considered in terms of a model which implies that the magnitude of the performance deficit depends on the performance type and the dosage level of the drug.

Kennedy, Robert S.↗