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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

CTB80 - A galactic radio source with directed jets

Recent investigations of the galactic radio source CTB 80 reveal several jet-like structures which can be traced outward to over 30 pc from a point less than 0.1 pc within a central core. If the object is associated with a supernova of 1408, then the jets must move out at a velocity of 0.2 C and can only be about 572 years old. The morphology of the whole source, however, suggests a significant, proper east to west motion of the central object, and indicates a much older age. In this case, continuous ejection into the jets would have occurred for tens of thousands of years. A quantitative explanation is presented in which the supernova explosion ejects several massive path-cutting fragments. It thus appears that the extended jets in CTB 80 do emanate from a small core which is energized by a compact object, but the source of this continuous ejection process still remains unknown

Dickel, J. R.↗
NASA NTRS1971

Extralunar dust in Apollo cores

Nuclear tracks high density in Apollo core small silicate crystals, discussing extralunar dust and photospheric iron-hydrogen ratio

Barber, D. J.↗
NASA NTRS1973

Properties of the solar nebula and the origin of the moon.

The basic geochemical model of the structure of the moon proposed by Anderson, in which the moon is formed by differentiation of the calcium, aluminium, and titanium-rich inclusions in the Allende meteorite, is accepted, and the conditions for formation of this moon within the solar nebula models of Cameron and Pine are discussed. The basic material condenses while iron remains in the gaseous phase, which places the formation of the moon slightly inside the orbit of Mercury. Some condensed metallic iron is likely to enter the moon in this position, and since the moon is assembled at a very high temperature, it is likely to have been fully molten, so that the iron can remove the iridium from the silicate material and carry it down to form a small core. Interactions between the moon and Mercury lead to the present rather eccentric Mercury orbit and to a much more eccentric orbit for the moon, reaching past the orbit of the earth, establishing conditions which are necessary for capture of the moon by the earth.

Cameron, A. G. W.↗
NASA NTRS1980

The X-ray structure of two rich galaxy clusters and its implications for the detectability of microwave diminutions

The X-ray observations of the galaxy clusters Abell 2319 and 576 show a reduced temperature of the microwave background due to the Suniaev-Zeldovich effect. The X-ray maps indicate smooth emission in these clusters concentrated toward the optical center; the surface brightness in the 1-3 keV band falls with the inverse square of radius outside a small core, and fits the Hubble's law of optical surface brightness of elliptical galaxies. The low temperature indicates that in A576 (1) the core radius of the gravitational potential is two to three times larger than inferred from galaxy counts, (2) the temperature rises with radius over most of the cluster and falls to zero at large radii, and (3) the gas does not obey the equation of state.

White, S. D. M.↗
NASA NTRS1980

Vector space methods of photometric analysis. II - Refinement of the MK grid for B stars. III - The two components of ultraviolet reddening

This paper discusses systematic errors which arise from exclusive use of the MK system to determine reddening. It is found that implementation of uvby, beta photometry to refine the qualitative MK grid substantially reduces stellar mismatch error. A working definition of 'identical' ubvy, beta types is investigated and the relationship of uvby to B-V color excesses is determined. A comparison is also made of the hydrogen based uvby, beta types with the MK system based on He and metal lines. A small core correlated effective temperature luminosity error in the MK system for the early B stars is observed along with a breakdown of the MK luminosity criteria for the late B stars. The second part investigates the wavelength dependence of interstellar extinction in the ultraviolet wavelength range observed with the TD-1 satellite. In this study the sets of identical stars employed to find reddening are determined more precisely than in previous studies and consist only of normal, nonsupergiant stars. A multivariate analysis of variance techniques in an unbiased coordinate system is used for determining the wavelength dependence of reddening.

Massa, D.↗
NASA NTRS1982

Microwaves and hard X-rays from solar flares - Multithermal and nonthermal interpretations

It is generally accepted that the hard X rays and centimeter-wavelength (microwave) radio emission from impulsive solar flares come from a common source. The present investigation is concerned with the development of a model for impulsive hard X rays and microwaves under the assumption that they arise from the same distribution of electrons, possibly, but not necessarily, from the same volume of space. An examination is conducted of a model in which the hard X rays and microwaves are produced in a homogeneous volume by a power-law electron distribution (nonthermal model). An investigation is also performed of a multithermal model in which the hard X rays and microwaves come from an inhomogeneous source, a nest of magnetic arches in which the highest temperature electrons are confined to a small core, and where, away from the core, the temperature decreases. It is found that more or less satisfactory models can be constructed using either multithermal or nonthermal, power-law electron distributions.

Dulk, G. A.↗
NASA NTRS1983

Experimental investigation of the partitioning of phosphorus between metal and silicate phases - Implications for the earth, moon and eucrite parent body

An experimental study is reported of the partitioning of Phosphorus between solid metal and basaltic silicate liquid as a function of temperature and oxygen fugacity and of the implications for the earth, moon and eucrite parent body (EPB). The relationship established between the partition coefficient and the fugacity is given at 1190 C by log D(P) = -1.12 log fO2 - 15.95 and by log D(P) = -1.53 log fO2 17.73 at 1300 C. The partition coefficient D(P) was determined, and it is found to be consistent with a valence state of 5 for P in the molten silicate. Using the determined coefficient the low P/La ratios of the earth, moon, and eucrites relative to C1 chondrites can be explained. The lowering of the P/La ratio in the eucrites relative to Cl chondrite by a factor of 40 can be explained by partitioning P into 20-25 wt% sulfur-bearing metallic liquid corresponding to 5-25% of the total metal plus silicate system. The low P/La and W/La ratios in the moon may be explained by the partitioning of P and W into metal during formation of a small core by separation of liquid metal from silicate at low degrees of partial melting of the silicates. These observations are consistent with independent formation of the moon and the earth.

Newsom, H. E.↗
NASA NTRS1987

Motion and decay of vortex rings submerged in a rotational flow

The interaction between vortex rings of finite strength and an axisymmetric rotational background flow is studied by a singular perturbation method, because it is difficult to use a finite-difference method to analyze the viscous decay in the small core of a vortex ring. The analysis is carried out by combining a composite solution of a vortex ring and an unsteady Euler solution for the background rotational flow. Using the method of averaging, a numerical scheme is developed to obtain an Euler solution in which the grid and time-step sizes depend solely on the length and velocity scales of the background flow. Numerical results are presented to illustrate the interaction between the trajectories and decay rates of the vortex rings and the background rotational flow.

Ishii, K.↗
NASA NTRS1992

Dynamical evolution effects on the hot stellar populations in globular clusters

Results of a study of FUV properties of Galactic globular clusters are presented. The spatially resolved spectra measured with the IUE satellite are used to find indications of color gradients in two clusters with the postcore-collapse (PCC) morphology, NGC 6752 and NGC 7099, but not in the case of NTGC 6093, a cluster with the classical King-model-type morphology. These FUV color gradients may be caused by the presence of a highly concentrated population of hot objects, such as the extreme BHB stars, blue stragglers, etc. This result extends to the FUV regime the trends seen in the ground-based data in the visible regime. PCC or highly concentrated small-core lusters are found to have bluer HB morphologies and bluer FUV colors, and the bluest FUV colors at a given metallicity. These trends indicate that dynamical evolution of clusters played some role in determining the net abundance and the spatial distribution of their hot stellar populations.

Djorgovski, S.↗
NASA NTRS1994

Imaging of 16 distant EMSS clusters with z greater than or equal to 0.2 and L(subx,44) greater than or equal to 4: New arcs and first consequences

Medium-deep V, R, and I observations of a subsample of 16 clusters of galaxies in the Experimental Mobile Satellite System (EMSS) sample defined from the Einstein satellite data are presented. Three new cases of clusters with giant luminous arcs (length/width greater than 10, V less than 22) have been discovered together with six new arcs (4 less than l/w less than 10, V less than 22), and we propose that these arcs are new examples of gravitational lensing of background galaxies by the rich clusters. Combined with giant luminous arcs already observed in the EMSS sample, there is a total of six giant luminous arcs observed in the sample of 16 clusters. This high rate of success in finding arcs added to their axis ratio distribution is consistent with very small core radii (less than 100 kpc) for the dark matter distribution in rich clusters, and rules out models in which dark matter follows the X-ray gas.

Le Fevre, O.↗
NASA NTRS2000

Fiber Optic Sensors for Health Monitoring of Morphing Airframes: Chemical Sensing Using Optical Fibers with Bragg Gratings - Part 2

Part 1 of this two part series described the fabrication and calibration of Bragg gratings written into a single mode optical fiber for use in strain and temperature monitoring. Part 2 of the series describes the use of identical fibers and additional multimode fibers, both with and without Bragg gratings, to perform near infrared spectroscopy. The demodulation system being developed at NASA Langley Research Center currently requires the use of a single mode optical fiber. Attempts to use this single mode fiber for spectroscopic analysis are problematic given its small core diameter, resulting in low signal intensity. Nonetheless, we have conducted a preliminary investigation using a single mode fiber in conjunction with an infrared spectrometer to obtain spectra of a high-performance epoxy resin system. Spectra were obtained using single mode fibers that contained Bragg gratings; however, the peaks of interest were barely discernible above the noise. The goal of this research is to provide a multipurpose sensor in a single optical fiber capable of measuring a variety of chemical and physical properties.

Wood, Karen↗
NASA NTRS2008

Framework for the Parametric System Modeling of Space Exploration Architectures

This paper presents a methodology for performing architecture definition and assessment prior to, or during, program formulation that utilizes a centralized, integrated architecture modeling framework operated by a small, core team of general space architects. This framework, known as the Exploration Architecture Model for IN-space and Earth-to-orbit (EXAMINE), enables: 1) a significantly larger fraction of an architecture trade space to be assessed in a given study timeframe; and 2) the complex element-to-element and element-to-system relationships to be quantitatively explored earlier in the design process. Discussion of the methodology advantages and disadvantages with respect to the distributed study team approach typically used within NASA to perform architecture studies is presented along with an overview of EXAMINE s functional components and tools. An example Mars transportation system architecture model is used to demonstrate EXAMINE s capabilities in this paper. However, the framework is generally applicable for exploration architecture modeling with destinations to any celestial body in the solar system.

Komar, David R.↗
NASA NTRS2009

Planetary Sample Caching System Design Options

Potential Mars Sample Return missions would aspire to collect small core and regolith samples using a rover with a sample acquisition tool and sample caching system. Samples would need to be stored in individual sealed tubes in a canister that could be transfered to a Mars ascent vehicle and returned to Earth. A sample handling, encapsulation and containerization system (SHEC) has been developed as part of an integrated system for acquiring and storing core samples for application to future potential MSR and other potential sample return missions. Requirements and design options for the SHEC system were studied and a recommended design concept developed. Two families of solutions were explored: 1)transfer of a raw sample from the tool to the SHEC subsystem and 2)transfer of a tube containing the sample to the SHEC subsystem. The recommended design utilizes sample tool bit change out as the mechanism for transferring tubes to and samples in tubes from the tool. The SHEC subsystem design, called the Bit Changeout Caching(BiCC) design, is intended for operations on a MER class rover.

MSR↗
NASA NTRS2015

CFD Analysis of Emissions for a Candidate N+3 Combustor

An effort was undertaken to analyze the performance of a model Lean-Direct Injection (LDI) combustor designed to meet emissions and performance goals for NASA's N+3 program. Computational predictions of Emissions Index (EINOx) and combustor exit temperature were obtained for operation at typical power conditions expected of a small-core, high pressure-ratio (greater than 50), high T3 inlet temperature (greater than 950K) N+3 combustor. Reacting-flow computations were performed with the National Combustion Code (NCC) for a model N+3 LDI combustor, which consisted of a nine-element LDI flame-tube derived from a previous generation (N+2) thirteen-element LDI design. A consistent approach to mesh-optimization, spraymodeling and kinetics-modeling was used, in order to leverage the lessons learned from previous N+2 flame-tube analysis with the NCC. The NCC predictions for the current, non-optimized N+3 combustor operating indicated a 74% increase in NOx emissions as compared to that of the emissions-optimized, parent N+2 LDI combustor.

nitrogen oxides↗
NASA NTRS2015

CFD Analysis of Emissions for a Candidate N+3 Combustor

An effort was undertaken to analyze the performance of a model Lean-Direct Injection (LDI) combustor designed to meet emissions and performance goals for NASA's N+3 program. Computational predictions of Emissions Index (EINOx) and combustor exit temperature were obtained for operation at typical power conditions expected of a small-core, high pressure-ratio (greater than 50), high T3 inlet temperature (greater than 950K) N+3 combustor. Reacting-flow computations were performed with the National Combustion Code (NCC) for a model N+3 LDI combustor, which consisted of a nine-element LDI flame-tube derived from a previous generation (N+2) thirteen-element LDI design. A consistent approach to mesh-optimization, spray-modeling and kinetics-modeling was used, in order to leverage the lessons learned from previous N+2 flame-tube analysis with the NCC. The NCC predictions for the current, non-optimized N+3 combustor operating indicated a 74% increase in NOx emissions as compared to that of the emissions-optimized, parent N+2 LDI combustor.

combustion chambers↗
NASA NTRS2017

A Parametric Study of Actuator Requirements for Active Turbine Tip Clearance Control of a Modern High Bypass Turbofan Engine

The efficiency of aircraft gas turbine engines is sensitive to the distance between the tips of its turbine blades and its shroud, which serves as its containment structure. Maintaining tighter clearance between these components has been shown to increase turbine efficiency, increase fuel efficiency, and reduce the turbine inlet temperature, and this correlates to a longer time-on-wing for the engine. Therefore, there is a desire to maintain a tight clearance in the turbine, which requires fast response active clearance control. Fast response active tip clearance control will require an actuator to modify the physical or effective tip clearance in the turbine. This paper evaluates the requirements of a generic active turbine tip clearance actuator for a modern commercial aircraft engine using the Commercial Modular Aero-Propulsion System Simulation 40k (C-MAPSS40k) software that has previously been integrated with a dynamic tip clearance model. A parametric study was performed in an attempt to evaluate requirements for control actuators in terms of bandwidth, rate limits, saturation limits, and deadband. Constraints on the weight of the actuation system and some considerations as to the force which the actuator must be capable of exerting and maintaining are also investigated. From the results, the relevant range of the evaluated actuator parameters can be extracted. Some additional discussion is provided on the challenges posed by the tip clearance control problem and the implications for future small core aircraft engines.

Turbine↗
NASA NTRS2018

NASA Emissions Research Overview

NASA Aeronautics is advancing a variety of technologies toward the objective of reducing aviation fuel burn and emissions. Specifically, the Advanced Air Transport Technology Project under the Advanced Air Vehicles Program is investing in technologies such as small core engines, fuel-flexible combustors, and electrified aircraft propulsion, all of which offer potential for reduced fleet fuel usage and harmful emissions. This presentation will provide a brief overview of these technical approaches as well as a NASA Aeronautics budget outlook.

Heidmann, Jim↗