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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

A NASA study of the impact of technology on future sea based attack aircraft

A conceptual aircraft design study was recently completed evaluating carrier-based, subsonic attack aircraft using contemporary and future technology assumptions. The study examined a configuration matrix that was made up of light and medium bomb loads, one and two man crews, internal and external weapons carriage, as well as conventional and flying wing planforms. Use of common technology assumptions, engine cycle simulation code, design mission, and consistent application of methods allow for direct comparison of the aircraft. This paper describes the design study ground rules and the aircraft designed. The aircraft descriptions include weights, dimensions, layout, design mission, design constraints, maneuver performance, and fallout mission performance. The strengths, and weaknesses of each aircraft are highlighted.

Hahn, Andrew S.↗
NASA NTRS2012

The Studies on Aerosol Transport, Its Deposition, and Its Impact on Climate - the Study on the Surface Material Circulation can Connect from the Past to the Future

Recently the issue on glacier retreats comes up and many factors should be relevant to the issue. The absorbing aerosols such as dust and black carbon (BC) are considered to be one of the factors. After they deposited onto the snow surface, it will reduce snow albedo (called snow darkening effect) and probably contribute to further melting of glacier. The Goddard Earth Observing System version 5 (GEOS-5) has developed at NASAlGSFC. However, the original snowpack model used in the land surface model in the GEOS-5 did not consider the snow darkening effect. Here we developed the new snow albedo scheme which can consider the snow darkening effect. In addition, another scheme on calculating mass concentrations on the absorbing aerosols in snowpack was also developed, in which the direct aerosol depositions from the chemical transport model in the GEOS-5 were used. The scheme has been validated with the observed data obtained at backyard of the Institute of Low Temperature Science, Hokkaido University, by Dr. Teruo Aoki (Meteorological Research Institute) et al. including me. The observed data was obtained when I was Ph.D. candidate. The original GEOS-5 during 2007-2009 over the Himalayas and Tibetan Plateau region showed more reductions of snow than that of the new GEOS-5 because the original one used lower albedo settings. On snow cover fraction, the new GEOS-5 simulated more realistic snow-covered area comparing to the MODIS snow cover fraction. The reductions on snow albedo, snow cover fraction, and snow water equivalent were seen with statistically significance if we consider the snow darkening effect comparing to the results without the snow darkening effect. In the real world, debris-cover, inside refreezing process, surface flow of lacier, etc. affect glacier mass balance and the simu.latedresults immediately do not affect whole glacier retreating. However, our results indicate that some surface melting over non debris-covered parts of the glacier would be explained by the snow darkening effect. Further discussion and observations are necessary to assess the glacier issue.

Yasunari, Teppei↗
NASA NTRSDate not supplied

Initial Exploratory Study of the Impacts of Climate Change on Air Traffic Operations

Climate change is already happening and is projected to accelerate in the future. It will persist for the foreseeable future, even with optimistic projections of technological advances and behavior changes. It will make aviation more and more challenging over time. Among other things, it is expected to cause increased severe weather, more extreme temperatures, and rising sea levels that constrain when, where, and how aircraft can fly. NASA has many prior, ongoing, and upcoming efforts towards mitigating the impacts of aviation on climate change. There is also a need to perform a comprehensive investigation of the reverse: that is, the impacts of climate change on aviation. This is an initial exploratory study on this topic utilizing the NAS Digital Twin—composed of the ATM TestBed simulation platform and NAS Digital Twin airspace management algorithms—to run NAS-wide simulations with Convective Weather Avoidance Model polygons at different avoidance thresholds to emulate the increase in severe weather that could manifest due to climate change. It was found that air traffic management may be able to limit the impact of climate change in terms of delay and fuel burn. However, increased severe weather due to climate change can make separation—particularly, aircraft-to-weather separation—more challenging by reducing available airspace and constraining the solution space. Challenging situations were identified and corresponding potential solutions were proposed towards ensuring air traffic operations continue to be robust and resilient to the impacts of increased severe weather due to climate change.

climate change, weather, air traffic operations↗
NASA NTRS1993

Space Technology: A study of the significance of recognition for innovators of spinoff technologies. A case study on the impact of the space technology hall of fame award

This report represents the preliminary effort in studying the significance of recognition for innovators of spinoff technologies. The purpose of this initial year's effort in this area was to gather preliminary data and define the direction for the remainder of the research. This report focuses on the most recent recipients of the Hall of Fame Award, the developers of liquid-cooled garments. Liquid-cooled garments technology and its spinoffs were used as a case study to define and explore the factors involved in technology transfer and to consider the possible incentives in developing commercial applications including the Hall of Fame Award. Through interviews, views of award recipients were obtained on factors encouraging spinoffs as well as impediments to spinoffs. The researchers observed complex inter-relationships among the significant entities (government, individuals, large and small business), the importance of people, the importance of resource availability, and the significance of intrinsic motivation; drew preliminary conclusions pertaining to the direct and indirect influence of recognition like the Hall of Fame Award; and planned the direction for next year's follow-on research.

Source record↗
NASA NTRS1979

Space shuttle orbiter trimmed center-of-gravity extension study. Volume 3: Impact of retrofits for center-of-gravity extension on orbiter thermal-protection system

Heat transfer studies were conducted at Mach 10.3 on space shuttle orbiter models with the S-2 fillet and C-4 canard retrofit moldlines which were generated in aerodynamic and system design studies to increase the allowable c.g. range of the orbiter. Areas of orbiter most strongly affected were the sides where a shear layer which separated along the wing leading edge impinged. Analytical studies of the heating effect on the thermal-protection system were made which indicated that scar weight on the orbiter sides due to allowances for retrofits of the S-2 fillet and C-4 canard is small (less than about 90 kg (200 lbs) in comparison to the total weight of the retrofit).

Dunavant, J. C.↗
NASA NTRS1991

Degradation studies of Martian impact craters

The amount of obliteration suffered by Martian impact craters is quantified by comparing measurable attributes of the current crater shape to those values expected for a fresh crater of identical size. Crater diameters are measured from profiles obtained using photoclinometry across the structure. The relationship between the diameter of a fresh crater and a crater depth, floor width, rim height, central peak height, etc. was determined by empirical studies performed on fresh Martian impact craters. We utilized the changes in crater depth and rim height to judge the degree of obliteration suffered by Martian impact craters.

Barlow, N. G.↗
NASA NTRS1976

SRB water impact velocity trade study

The results of the attrition/cost studies which formulated the data base for the recommendation to reduce the Space Shuttle Solid Rocket Booster's nominal vertical water impact velocity to 85 feet per second is presented.

Counter, D. N.↗
NASA NTRS1992

A NASA study of the impact of technology on future carrier based tactical aircraft - Overview

This paper examines the impact of technology on future carrier based tactical aircraft. The results were used in the Center for Naval Analysis Future Carrier Study. The NASA Team designed three classes of aircraft ('Fighter', 'Attack', and 'Multimission') with two different technology levels. The Multimission aircraft were further analyzed by examining the penalty on the aircraft for both catapult launch/arrested landing recovery (Cat/trap) and short take-off/vertical landing (STOVL). The study showed the so-called STOVL penalty was reduced by engine technology and the next generation Strike Fighter will pay more penalty for Cat/trap than for STOVL capability.

Wilson, S. B., III↗
NASA NTRS2013

Impacts of Climate Change on Surface Ozone and Intercontinental Ozone Pollution: A Multi-Model Study

The impact of climate change between 2000 and 2095 SRES A2 climates on surface ozone (O)3 and on O3 source-receptor (S-R) relationships is quantified using three coupled climate-chemistry models (CCMs). The CCMs exhibit considerable variability in the spatial extent and location of surface O3 increases that occur within parts of high NOx emission source regions (up to 6 ppbv in the annual average and up to 14 ppbv in the season of maximum O3). In these source regions, all three CCMs show a positive relationship between surface O3 change and temperature change. Sensitivity simulations show that a combination of three individual chemical processes-(i) enhanced PAN decomposition, (ii) higher water vapor concentrations, and (iii) enhanced isoprene emission-largely reproduces the global spatial pattern of annual-mean surface O3 response due to climate change (R2 = 0.52). Changes in climate are found to exert a stronger control on the annual-mean surface O3 response through changes in climate-sensitive O3 chemistry than through changes in transport as evaluated from idealized CO-like tracer concentrations. All three CCMs exhibit a similar spatial pattern of annual-mean surface O3 change to 20% regional O3 precursor emission reductions under future climate compared to the same emission reductions applied under present-day climate. The surface O3 response to emission reductions is larger over the source region and smaller downwind in the future than under present-day conditions. All three CCMs show areas within Europe where regional emission reductions larger than 20% are required to compensate climate change impacts on annual-mean surface O3.

Troposphere: constituent transport and chemistry↗
NASA NTRS2003

A Study of the Impact of Variations on Aerodynamic Flow in Gas Turbine Engines via Monte-Carlo Simulations

The unsteady compressible inviscid flow is characterized by the conservations of mass, momentum, and energy; or simply the Euler equations. In this paper, a study of the subsonic one-dimensional Euler equations with local preconditioning is presented with a modal analysis approach. Specifically, this study investigates the behavior of airflow in a gas turbine engine using the specified conditions at the inflow and outflow boundaries of the compressor, combustion chamber, and turbine, under the impact of variations in pressure, velocity, temperature, and density at low Mach numbers. Two main questions that motivate this research are: 1) Is there any aerodynamic problem with the existing gas turbine engines that could impact aircraft performance? 2) If yes, what aspect of a gas turbine engine could be improved via design to alleviate that impact and to optimize aircraft performance. This paper presents an initial attempt to the flow behavior in terms (perturbation) using simulation outputs from a customer-deck model obtained from Pratt&Whitney, (i.e., pressure, temperature, velocity, density) about their mean states at the inflow and outflow boundaries of the compressor, combustion chamber, and turbine. Flow behavior is analyzed for the high pressure compressor and combustion chamber employing the conditions on their left and right boundaries. In the same fashion, similar analyses are carried out for the high and low-pressure turbines. In each case, the eigenfrequencies that are obtained for different boundary conditions are examined closely based on their probabilistic distributions, a result of a Monte Carlo 10,000-sample simulation. Furthermore, the characteristic waves and eave response are analyzed and contrasted among different cases, with and without preconditioners. The results reveal the existence of flow instabilities due to the combined effect of variations and excessive pressures; which are clearly the case in the combustion chamber and high-pressure turbine. Finally a discussion is presented on potential impacts of the instabilities and what can be improved via design to alleviate them for a better aircraft performance.

Ngo, Khiem Viet↗
NASA NTRS1988

Assessment of satellite communications quality study. Addendum 1: Impact of propagation delay on data transmission

The single factor that irrevocably distinguishes geostationary satellite telephony transmission from terrestrial transmission is the greater propagation delay over satellite links. This difference has always provoked vigorous debate over the impact of delay on the subscribers using services incorporating satellite links. The issue is addressed from a variety of directions including human factors studies, laboratory subjective tests that evaluate delay with and without echo, and field tests that obtain data on the opinion of subscribers regarding the quality of service of operational circuits in both national U.S. domestic and international trans-Atlantic network. The tests involved the use of both echo suppressors and echo cancellers.

Campanella, S. J.↗
NASA NTRS2003

Results of the Workshop on Impact Cratering: Bridging the Gap Between Modeling and Observations

On February 7-9,2003, approximately 60 scientists gathered at the Lunar and Planetary Institute in Houston, Texas, for a workshop devoted to improving knowledge of the impact cratering process. We (co-conveners Elisabetta Pierazzo and Robert Herrick) both focus research efforts on studying the impact cratering process, but the former specializes in numerical modeling while the latter draws inferences from observations of planetary craters. Significant work has been done in several key areas of impact studies over the past several years, but in many respects there seem to be a disconnect between the groups employing different approaches, in particular modeling versus observations. The goal in convening this workshop was to bring together these disparate groups to have an open dialogue for the purposes of answering outstanding questions about the impact process and setting future research directions. We were successful in getting participation from most of the major research groups studying the impact process. Participants gathered from five continents with research specialties ranging from numerical modeling to field geology, and from small-scale experimentation and geochemical sample analysis to seismology and remote sensing.With the assistance of the scientific advisory committee (Bevan French, Kevin Housen, Bill McKinnon, Jay Melosh, and Mike Zolensky), the workshop was divided into a series of sessions devoted to different aspects of the cratering process. Each session was opened by two invited t a b , one given by a specialist in numerical or experimental modeling approaches, and the other by a specialist in geological, geophysical, or geochemical observations. Shorter invited and contributed talks filled out the sessions, which were then concluded with an open discussion time. All modelers were requested to address the question of what observations would better constrain their models, and all observationists were requested to discuss how their observations can constrain modeling efforts.

Herrick, Robert↗
NASA NTRS1997

A Study of the Use of Contact Loading to Simulate Low Velocity Impact

Although numerous studies on the impact response of laminated composites have been conducted, there is as yet no agreement within the composites community on what parameter or parameters are adequate for quantifying the severity of an impact event. One of the more interesting approaches that has been proposed uses the maximum contact force during impact to "quantify" the severity of the impact event, provided that the impact velocity is sufficiently low. A significant advantage of this approach, should it prove to be reliable, is that quasi-static contact loading could be used to simulate low velocity impact. In principle, a single specimen, loaded quasi-statically to successively increasing contact loads could be used to map the entire spectrum of damage as a function of maximum contact force. The present study had as its objective assessing whether or not the maximum contact force during impact is a suitable parameter for characterizing an impact. The response of [+/-60/0(sub 4)/+/-60/0(sub 2)](sub s) laminates fabricated from Fiberite T300/934 graphite epoxy and subjected to quasi-static contact loading and to low velocity impact was studied. Three quasi-static contact load levels - 525 lb., 600 lb., and 675 lb. - were selected. Three impact energy levels - 1.14 ft.-lb., 2.0 ft.-lb., and 2.60 ft.-lb. - were chosen in an effort to produce impact events in which the maximum contact forces during the impact events were 525 lb., 600 lb., and 625 lb., respectively. Damage development was documented using dye-penetrant enhanced x-ray radiography. A digital image processing technique was used to obtain quantitative information about the damage zone. Although it was intended that the impact load levels produce maximum contact forces equal to those used in the quasi-static contact experiments, larger contact forces were developed during impact loading. In spite of this, the damage zones developed in impacted specimens were smaller than the damage zones developed in specimens subjected to the corresponding quasi-static contact loading. The impacted specimens may have a greater tendency to develop fiber fracture, but, at present, a quantitative assessment of fiber fracture is not available. In addressing whether or not contact force is an adequate metric for describing the severity of an impact event, the results of this study suggest that it is not. In cases where the quasi-static load level and the maximum contact force during impact were comparable, the quasi-statically loaded specimens consistently developed larger damage zones. It should be noted, however, that using quasi-static damage data to forecast the behavior of impacted material may give conservative estimates of the residual strength of impacted composites.

Highsmith, Alton L.↗
NASA NTRS1991

Study of meteoroid impact craters on various materials (AO 138-1). Attempt at dust debris collection with stacked detectors (AO 138-2)

Part of the Long Duration Exposure Facility (LDEF) tray allocated to French experiments, known as FRECOPA payload, was devoted to the study of dust particles. Two passive experiments were flown: one composed of a set of glass and metallic samples and one composed of multilayer thin foils detectors. In addition to these experiments, a broad variety of materials were exposed to the bombardment of microparticles and provide more data. Thick target experiment comprises selected metallic (Al, Au, Cu, W, Stainless Steel) 250 microns thick and glass surfaces 1.5 mm thick. Crater size distribution from these thick target experiments enable, with the aid of lab calibrations by solid particle accelerators, the evaluation of the incident microparticle flux in the near earth environment. The aim of the multiple foil penetration and collection experiment is primarily to study the feasibility of multilayer thin film detectors acting as energy sorters in order to collect micrometeoroids, if not in their original shape, at least as 'breakup' fragments suitable for chemical analysis. Foil thicknesses range from 0.75 to 5 microns of Al.

Mandeville, Jean Claude↗
NASA NTRS1976

Study of operational parameters impacting helicopter fuel consumption

A computerized study of operational parameters affecting helicopter fuel consumption was conducted as an integral part of the NASA Civil Helicopter Technology Program. The study utilized the Helicopter Sizing and Performance Computer Program (HESCOMP) developed by the Boeing-Vertol Company and NASA Ames Research Center. An introduction to HESCOMP is incorporated in this report. The results presented were calculated using the NASA CH-53 civil helicopter research aircraft specifications. Plots from which optimum flight conditions for minimum fuel use that can be obtained are presented for this aircraft. The results of the study are considered to be generally indicative of trends for all helicopters.

Cross, J. L.↗
NASA NTRS1978

A chemical study of the impact glasses and basalts from Lonar Crater, India

Twenty-nine elements were determined by instrumental neutron activation analysis in two impact glasses and four basalts from Lonar Crater, India, and the glasses and the underlying core basalt samples are found to be very similar in major, minor, and trace element abundances. This finding seems to indicate that impact-induced chemical fractionation during formation of the glasses from basalt is minimal for many of the principal rock and mineral-forming elements. Since most volatile trace elements were not determined in this study, differences in the volatile trace element contents of the glasses and basalts can not be excluded.

Stroube, W. B., Jr.↗
NASA NTRS2011

Multiple Spacecraft Study of the Impact of Turbulence on Reconnection Rates

Magnetic turbulence and secondary island formation have reemerged as possible explanations for fast reconnection. Recent three-dimensional simulations reveal the formation of secondary islands that serve to shorten the current sheet and increase the accelerating electric field, while both simulations and observations witness electron holes whose collapse energizes electrons. However, few data studies have explicitly investigated the effect of turbulence and islands on the reconnection rate. We present a more comprehensive analysis of the effect of turbulence and islands on reconnection rates observed in space. Our approach takes advantage of multiple spacecraft to find the location of the spacecraft relative to the inflow and the outflow, to estimate the reconnection electric field, to indicate the presence and size of islands, and to determine wave vectors indicating turbulence. A superposed epoch analysis provides independent estimates of spatial scales and a reconnection electric field. We apply k-filtering and a new method adopted from seismological analyses to identify the wavevectors. From several case studies of reconnection events, we obtain preliminary estimates of the spectral scaling law, identify wave modes, and present a method for finding the reconnection electric field associated with the wave modes.

Wendel, Deirdre↗