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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 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Sodium-sulfur batteries for spacecraft energy storage

Power levels for future space missions will be much higher than are presently attainable using nickel-cadmium and nickel-hydrogen batteries. Development of a high energy density rechargeable battery is essential in being able to provide these higher power levels without tremendous weight penalties. Studies conducted by both the Air Force and private industry have identified the sodium-sulfur battery as the best candidate for a next generation battery system. The advantages of the sodium-sulfur battery over the nickel-cadmium battery are discussed.

Dueber, R. E.↗
NASA NTRS1989

Energy-absorption capability of composite tubes and beams

In this study the objective was to develop a method of predicting the energy-absorption capability of composite subfloor beam structures. Before it is possible to develop such an analysis capability, an in-depth understanding of the crushing process of composite materials must be achieved. Many variables affect the crushing process of composite structures, such as the constituent materials' mechanical properties, specimen geometry, and crushing speed. A comprehensive experimental evaluation of tube specimens was conducted to develop insight into how composite structural elements crush and what are the controlling mechanisms. In this study the four characteristic crushing modes, transverse shearing, brittle fracturing, lamina bending, and local buckling were identified and the mechanisms that control the crushing process defined. An in-depth understanding was developed of how material properties affect energy-absorption capability. For example, an increase in fiber and matrix stiffness and failure strain can, depending upon the configuration of the tube, increase energy-absorption capability. An analysis to predict the energy-absorption capability of composite tube specimens was developed and verified. Good agreement between experiment and prediction was obtained.

Farley, Gary L.↗
NASA NTRS1991

Residual thermal and moisture influences on the strain energy release rate analysis of local delaminations from matrix cracks

An analysis utilizing laminated plate theory is developed to calculate the strain energy release rate associated with local delaminations originating at off-axis, single ply, matrix cracks in laminates subjected to uniaxial loads. The analysis includes the contribution of residual thermal and moisture stresses to the strain energy released. Examples are calculated for the strain energy release rate associated with local delaminations originating at 90 degrees and angle-ply (non-90 degrees) matrix ply cracks in glass epoxy and graphite epoxy laminates. The solution developed may be used to assess the relative contribution of mechanical, residual thermal, and moisture stresses on the strain energy release rate for local delamination for a variety of layups and materials.

Obrien, T. K.↗
NASA NTRS1981

A prediction model for bipolar RAMs in a high energy ion/proton environment

A model has been developed which predicts the relative susceptibility of bipolar RAMs to heavy ion and proton upset. During the course of evaluating this model, physical and electrical variations were also evaluated indicating that the minimum internal signal level is the primary upset susceptibility indicator. Unfortunately, all of the physical and electrical variations expected during a normal product development cycle are in direct opposition to improved high-energy particle upset tolerance. Hence, a trade-off between highly susceptible, low power (medium speed) devices must be made against the less susceptible, higher power (high speed) equivalent device, taking into account the systems trade-off with respect to system power, software, error correction procedures and/or circuit redundancy.

Myers, D. K.↗
NASA NTRS1983

The coupled aeroelastic response of turbomachinery blading to aerodynamic excitations

An energy balance technique is developed to predict the coupled bending-torsion mode aerodynamically forced response of an airfoil. In this technique, the energy input to the airfoil system per cycle of oscillation is generated by gust forces and moments and, under certain conditions, the self-induced aerodynamic forces and moments. The energy dissipation per cycle is associated with the structural damping, the static moment term for coupled motions, and under certain conditions, the self-induced aerodynamic forces and moments. The effects of the various aerodynamic parameters on the coupled forced response are then considered.In particular, the effects of the inlet Mach number, the interblade phase angle, the level of structural damping, and the cascade geometry on the coupled bending-torsion aerodynamically forced response of a flat plate airfoil cascade are demonstrated.

Hoyniak, D.↗
NASA NTRS1987

Past, present, and future activities in space power technology in the United States of America

Space power technology research in the U.S. is examined. The objectives for advanced power systems are long life, safety, flexibility, modularity, growth capability, and autonomy. Research in the areas of photovoltaic arrays, electrical energy storage, and the development of solar dynamic power systems and radio thermal generators is described. The applications of advances in power generation, energy storage, and power management and distribution to the Space Station are discussed.

Ambrus, Judith H.↗
NASA NTRS1990

Solar flares

General characteristics of solar flares are discussed. They are a spectacular energy release arising from development of magnetic strain and shear, resulting from eruption of new magnetic flux near old. The release of magnetic energy is channeled into hard electrons (and possibly nucleons), which produce a series of other effects. The ultimate source of the magnetic complexity that produces flares is deep in the sun. A number of examples is given, and the difference between various types of flares is discussed.

Zirin, Harold↗
NASA NTRS2009

Radioisotope Electric Propulsion (REP): A Near-Term Approach to Nuclear Propulsion

Studies over the last decade have shown radioisotope-based nuclear electric propulsion to be enhancing and, in some cases, enabling for many potential robotic science missions. Also known as radioisotope electric propulsion (REP), the technology offers the performance advantages of traditional reactor-powered electric propulsion (i.e., high specific impulse propulsion at large distances from the Sun), but with much smaller, affordable spacecraft. Future use of REP requires development of radioisotope power sources with system specific powers well above that of current systems. The US Department of Energy and NASA have developed an advanced Stirling radioisotope generator (ASRG) engineering unit, which was subjected to rigorous flight qualification-level tests in 2008, and began extended lifetime testing later that year. This advancement, along with recent work on small ion thrusters and life extension technology for Hall thrusters, could enable missions using REP sometime during the next decade.

Schmidt, George R.↗
NASA NTRS1972

Stored energy function of rubberlike materials derived from simple tensile data.

An explicit formulation is developed to obtain the stored energy function, based on the Valanis-Landel separable symmetric stored energy function. This formulation is applicable to any multiaxial stress state, from simple tensile data alone, for those cases in which the stored energy function is a separable function of the stretch ratios. By direct comparison, it is also shown that styrene butadiene rubber, at least over a specific range, follows this postulated separable form.

Peng, T. J.↗
NASA NTRS1993

Development of first generation aerospace NiMH cells

Gates Aerospace Batteries in conjunction with Gates Energy Products (GEP) has been developing NiMH technology for aerospace use since 1990. GEP undertook the development of NiMH technology for commercial cell applications in 1987. This program focused on wound cell technology for replacement of current NiCd technology. As an off shoot of this program small, wound cells were used to evaluate initial design options for aerospace prismatic cell designs. Early in 1991, the first aerospace prismatic cell designs were built in a 6 Ah cell configuration. These cells were used to initially characterize performance in prismatic configurations and begin early life cycle testing. Soon after the 6 Ah cells were on test, several 22 Ah cells were built to test other options. The results of testing of these cells were used to identify potential problem areas for long lived cells and develop solutions to those problems. Following these two cell builds, a set of 7 Ah cells was built to evaluate improvements to the technology. To date results from these tests are very promising. Cycle lives in excess of 2,200 LEO cycles at 50 percent DoD were achieved with cells continuing on test. Results from these cell tests are discussed and data presented to demonstrate feasibility of this technology for aerospace programs.

Tinker, Lawrence↗
NASA NTRS1976

Air-bearing spin facility for measuring energy dissipation

The air-bearing spin facility was developed to determine experimentally the effect of energy dissipation upon the motion of spinning spacecraft. The facility consists of an air-bearing spin table, a telemetry system, a command system, and a ground control station. The air-bearing spin table was designed to operate in a vacuum chamber. Tests were run on spacecraft components such as fuel tanks, nutation dampers, reaction wheels, and active nutation damper systems. Each of these items affected the attitude of a spinning spacecraft. An experimental approach to determine these effects was required because the dissipation of these components could not be adequately analyzed. The results of these experiments have been used, with excellent results, to predict spacecraft motion.

Peterson, R. L.↗
NASA NTRS1995

Surface conversion techniques for low energy neutral atom imagers

This investigation has focused on development of key technology elements for low energy neutral atom imaging. More specifically, we have investigated the conversion of low energy neutral atoms to negatively charged ions upon reflection from specially prepared surfaces. This 'surface conversion' technique appears to offer a unique capability of detecting, and thus imaging, neutral atoms at energies of 0.01 - 1 keV with high enough efficiencies to make practical its application to low energy neutral atom imaging in space. Such imaging offers the opportunity to obtain the first instantaneous global maps of macroscopic plasma features and their temporal variation. Through previous in situ plasma measurements, we have a statistical picture of large scale morphology and local measurements of dynamic processes. However, with in situ techniques it is impossible to characterize or understand many of the global plasma transport and energization processes. A series of global plasma images would greatly advance our understanding of these processes and would provide the context for interpreting previous and future in situ measurements. Fast neutral atoms, created from ions that are neutralized in collisions with exospheric neutrals, offer the means for remotely imaging plasma populations. Energy and mass analysis of these neutrals provides critical information about the source plasma distribution. The flux of neutral atoms available for imaging depends upon a convolution of the ambient plasma distribution with the charge exchange cross section for the background neutral population. Some of the highest signals are at relatively low energies (well below 1 keV). This energy range also includes some of the most important plasma populations to be imaged, for example the base of the cleft ion fountain.

Quinn, J. M.↗
NASA NTRS2010

In the Beginning...

Having just emerged from the warmest decade on record and watching as the oceans acidify and sea level rises, global resources peak, the world's population continues to climb, and nearly half of all known species face extinction by the end of the century. We stand on the threshold of one of the most important transition in human history-the transition from hunting-and-gathering our energy to cultivating sustainable, carbon-neutral, environmentally-friendly energy supplies. Can we develop an alternative to fossil fuels in time to make a difference for our children and the "children" of all species? NASA puts people into outer space, where all resources (food, water, air, pressure, gravity, energy) are limited and far away and where conditions (temperature, radiation, vacuum) are problematic and dangerous-the life expectancy of an unprotected astronaut (physically exposed to the space environment) is 15 seconds. Therefore, by necessity, NASA has explored and developed "life-support systems" that optimize the use of resources, minimize the use of energy, and recycle, refurbish, re-use everything that on earth would be considered a waste material. Emerging from the legacy of life-support systems, the NASA OMEGA project uses microalgae, municipal wastewater, and the encroaching oceans to address our global needs for a sustainable, carbon-neutral, environmentally friendly energy supply that does not compete with agriculture. The OMEGA project is focused on producing aviation fuel, treating municipal wastewater, and sequestering carbon dioxide. More generally, however, OMEGA is an example of an "ecology of technologies" in which all processes are integrated and inter-dependent and wastes become resources. From a NASA perspective, the OMEGA project is also a reminder that "we are not passengers on Spaceship Earth, we are the crew."

Trent, Jonathan↗
NASA NTRS1982

Energy Efficient Engine (E3) controls and accessories detail design report

An Energy Efficient Engine program has been established by NASA to develop technology for improving the energy efficiency of future commercial transport aircraft engines. As part of this program, a new turbofan engine was designed. This report describes the fuel and control system for this engine. The system design is based on many of the proven concepts and component designs used on the General Electric CF6 family of engines. One significant difference is the incorporation of digital electronic computation in place of the hydromechanical computation currently used.

Beitler, R. S.↗
NASA NTRS1986

Generalization and extension of the law of acoustic energy conservation in a nonuniform flow

An exact conservation equation is derived which generalizes the familiar acoustic energy equations. The new relation is valid for arbitrary disturbances to a viscous, compressible flow. It is suggested by a development of the acoustic energy equation by means of a regular perturbation expansion of the general energy equation of fluid mechanics. A perturbation energy density and flux are defined and identified as the exact physical quantities whose leading order perturbation representations are the usual acoustic energy density and flux. The conservation equation governing the perturbation energy quantities is shown to yield previously known results for several special cases.

Myers, M. K.↗
NASA NTRS1990

Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields

The primary tasks during January 1990 to June 1990 have been the development and evaluation of various electron and electron-electronic energy equation models, the continued development of improved nonequilibrium radiation models for molecules and atoms, and the continued development and investigation of precursor models and their effects. In addition, work was initiated to develop a vibrational model for the viscous shock layer (VSL) nonequilibrium chemistry blunt body engineering code. Also, an effort was started associated with the effects of including carbon species, say from an ablator, in the flowfield.

Carlson, Leland A.↗
NASA NTRS2005

Optimal Sampling of a Reaction Coordinate in Molecular Dynamics

Estimating how free energy changes with the state of a system is a central goal in applications of statistical mechanics to problems of chemical or biological interest. From these free energy changes it is possible, for example, to establish which states of the system are stable, what are their probabilities and how the equilibria between these states are influenced by external conditions. Free energies are also of great utility in determining kinetics of transitions between different states. A variety of methods have been developed to compute free energies of condensed phase systems. Here, I will focus on one class of methods - those that allow for calculating free energy changes along one or several generalized coordinates in the system, often called reaction coordinates or order parameters . Considering that in almost all cases of practical interest a significant computational effort is required to determine free energy changes along such coordinates it is hardly surprising that efficiencies of different methods are of great concern. In most cases, the main difficulty is associated with its shape along the reaction coordinate. If the free energy changes markedly along this coordinate Boltzmann sampling of its different values becomes highly non-uniform. This, in turn, may have considerable, detrimental effect on the performance of many methods for calculating free energies.

Pohorille, Andrew↗
NASA NTRS2009

Synthetic and Biomass Alternate Fueling in Aviation

Must use earth's most abundant natural resources - Biomass, Solar, Arid land (43%), Seawater (97%) with nutrients (80%) plus brackish waters and nutrients resolve environmental triangle of conflicts energy-food-freshwater and ultrafine particulate hazards. Requires Paradigm Shift - Develop and Use Solar* for energy; Biomass for aviation and hybrid-electric-compressed air mobility fueling with transition to hydrogen long term.

Hendricks, Robert C.↗