SEARCH · Engineering Papers

Results for “Component sizing”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17

All sources NASA NTRS DOE OSTI

NASA NTRS1985

Fabrication of ceramic components for advanced gas turbine engines

The AGT101 ceramic gas turbine engine feasibility study has made use of the slip casting of silicon or silicon nitride powders to produce either reaction-bonded or sintered components such as turbine rotors, turbine shrouds, and inner and outer diffusers. Attention is given to the effects of processing parameters on the microstructure and properties of the finished components; the parameters encompass powder particle size distribution, casting slip viscosity, pH, and solid content fraction. The green slip cast components were consolidated by nitriding, sintering, or sinter/HIPping.

Liu, F.↗

NASA NTRS2010

Florida Tech CubeSat Experiment Feasibility Study

CubeSats are a relatively new type of satellite. Smaller than long-term (5+ year life expectancy) satellites, these pico-satellites are comparatively cheap, small (10x10x10 cm), and are very versatile. Universities world-wide are using CubeSats to conduct a variety of experiments in space without the need for a large experimental platform. Today CubeSats are considered to be one of the most effective ways to send a small payload into space and has attracted the attention of many educational and non-profit organizations. As this pico-satellite model continues to gain penetration into the satellite build and launch industry, it is expected that more governmental, educational, and commercial interests will emerge. As an example, more of the space-related items of high interest to the National Science Foundation may be tackled with a CubeSat platform resulting in lower life cycle costs than traditional satellite options. NASA LSP, in cooperation with the Florida Institute of Technology, has initiated a feasibility study to investigate the technical aspects of measuring and transferring vibration, acceleration, temperature, and video data from a CubeSat to NASA Hanger AE on Cape Canaveral Air Force Station (CCAFS) a.k.a. Kennedy Space Center (KSC). This report provides a technical feasibility analysis to determine whether-or-not a specific set of NASA/LSP requirements can be accomplished. Our approach has been to provide a "notional" component layout to determine the feasibility of the NASA/LSP stakeholder requirements. The notional layout is used to consider component level technical issues such as size, weight, & power (SWaP), bandwidth, and other critical technical parameters. Even though the notional components may satisfy the stated requirements and thereby demonstrate feasibility, the notional layout is NOT considered a design since no component optimization and design trade-off analysis has taken place. This activity should be accomplished in an appropriate design phase that is outside of the scope of this effort.

Arrasmith, William W.↗

NASA NTRS1988

Moisture adsorption in optical coatings

The thin film filter is a very large aperture component which is exceedingly useful because of its small size, flexibility and ease of mounting. Thin film components, however, do have defects of performance and especially of stability which can cause problems in systems, particularly where long-term measurements are being made. Of all of the problems, those associated with moisture absorption are the most serious. Moisture absorption occurs in the pore-shaped voids inherent in the columnar structure of the layers. Ion-assisted deposition is a promising technique for substantially reducing moisture adsorption effects in thin film structures.

Macleod, H. Angus↗

NASA NTRS1993

The mid-infrared reflectance of mineral mixtures (7-14 microns)

Mid-infrared reflectance spectra were measured (using an interferometer spectrometer with a 4/cm resolution) of a number of mineral mixtures (including quartz-microcline, quartz-hornblende, microcline-albite, microcline-hornblende, albite-hornblende, and albite-augite mixtures containing different proportions of the components, each in the 75-250 micron size range), and the spectra were compared with those of single components. It is shown that the mid-infrared reflectance spectra of particulate mixtures of these minerals combine linearly by volume within a very small error, as long as particles are much larger than the wavelength.

Thomson, Janice L.↗

NASA NTRS1980

Status of nickel-hydrogen cell technology

Nickel hydrogen cell technology has been developed which solves the problems of thermal management, oxygen management, electrolyte management, and electrical and mechanical design peculiar to this new type of battery. This technology was weight optimized for low orbit operation using computer modeling programs but is near optimum for other orbits. Cells ranging in capacity up to about 70 ampere-hours can be made from components of a single standard size and are available from two manufacturers. The knowledge gained is now being applied to the development of two extensions to the basic design: a second set of larger standard components that will cover the capacity range up to 150 ampere-hours; and the development of multicell common pressure vessel modules to reduce volume, cost and weight. A manufacturing technology program is planned to optimize the producibility of the cell design and reduce cost. The most important areas for further improvement are life and reliability which are governed by electrode and separator technology.

Warnock, D. R.↗

NASA NTRS2003

Toroidal-Core Microinductors Biased by Permanent Magnets

The designs of microscopic toroidal-core inductors in integrated circuits of DC-to-DC voltage converters would be modified, according to a proposal, by filling the gaps in the cores with permanent magnets that would apply bias fluxes (see figure). The magnitudes and polarities of the bias fluxes would be tailored to counteract the DC fluxes generated by the DC components of the currents in the inductor windings, such that it would be possible to either reduce the sizes of the cores or increase the AC components of the currents in the cores without incurring adverse effects. Reducing the sizes of the cores could save significant amounts of space on integrated circuits because relative to other integrated-circuit components, microinductors occupy large areas - of the order of a square millimeter each. An important consideration in the design of such an inductor is preventing magnetic saturation of the core at current levels up to the maximum anticipated operating current. The requirement to prevent saturation, as well as other requirements and constraints upon the design of the core are expressed by several equations based on the traditional magnetic-circuit approximation. The equations involve the core and gap dimensions and the magnetic-property parameters of the core and magnet materials. The equations show that, other things remaining equal, as the maximum current is increased, one must increase the size of the core to prevent the flux density from rising to the saturation level. By using a permanent bias flux to oppose the flux generated by the DC component of the current, one would reduce the net DC component of flux in the core, making it possible to reduce the core size needed to prevent the total flux density (sum of DC and AC components) from rising to the saturation level. Alternatively, one could take advantage of the reduction of the net DC component of flux by increasing the allowable AC component of flux and the corresponding AC component of current. In either case, permanent-magnet material and the slant (if any) and thickness of the gap must be chosen according to the equations to obtain the required bias flux. In modifying the design of the inductor, one must ensure that the inductance is not altered. The simplest way to preserve the original value of inductance would be to leave the gap dimensions unchanged and fill the gap with a permanent- magnet material that, fortuitously, would produce just the required bias flux. A more generally applicable alternative would be to partly fill either the original gap or a slightly enlarged gap with a suitable permanent-magnet material (thereby leaving a small residual gap) so that the reluctance of the resulting magnetic circuit would yield the desired inductance.

Lieneweg, Udo↗

NASA NTRS1975

Diffraction analysis of Doppler signal characteristics for a cross-beam laser Doppler velocimeter

Based on scalar diffraction theory, single particle scattering characteristics for a cross-beam laser Doppler velocimeter (LDV) have been computed for different particle sizes under varied instrumentation configurations. The modulating component of the scattered signal has been shown to depend upon particle size, shape, and collecting aperture for a given probe volume fringe spacing. Experimental verifications of some of the predictions are presented, and some of the limitations using an LDV as a particle sizing instrument are discussed.

Robinson, D. M.↗

NASA NTRSDate not supplied

Computationally Guided Development of Components for High Energy Density Solid-State Lithium-Sulfur Batteries

All electric vertical take-off and landing vehicles (eVTOL) for urban air mobility (UAM) concepts face numerous challenging technical barriers before their introduction into the consumer marketplace. The most challenging of these technical barriers to overcome is developing an energy storage system capable of meeting the rigorous aerospace safety and performance criteria1. The performance metrics for eVTOL craft, such as specific energy, specific power, and safety, exceed those of electric automobiles by a factor of two to four. Current state-of-the-art (SOA) lithium-ion batteries are incapable of meeting the key performance criteria of energy and safety for eVTOL. Therefore, next generation advanced chemistries and designs must be developed to meet required performance metrics for electric aviation2. Beyond lithium-ion chemistries, such as lithium-sulfur, show promise in their high energy, while limitations exist in their power and cyclability due to low electrical conductivity and high intermediate solubility in organic liquid electrolytes. Several strategies to overcome the low electrical conductivity involve the use of selenium as a dopant in the active sulfur material, along with the incorporation of 2-dimensional electron-conducting holey-graphene to improve the composite cathodes electronic conductivity. Furthermore, combining this chemistry with a solid-electrolyte avoids the components’ dissolution issues3. However, the development of composite solid-state cathodes is non-trivial as several components must be intimately mixed so that the active component has sufficient access to both electrons and lithium ions to undergo full electrochemical conversion. Mathematical modeling of battery components can assist experimental design through a robust and rigorous combination of computational modeling techniques covering multiple length scales. The objective is to leverage modern computational materials methods combined with battery multiphysics tools to develop radically advanced compatible cathode and electrolyte materials, build and test solid state lithium-sulfur cells and packs. A NASA-based cross-organizational team of high-powered experts combined integrated computational predictive modeling, fundamental chemistry analysis, advanced material science, and battery cell development to tackle this very challenging, multidisciplinary problem. This presentation will show a multiscale computational modeling approach that has produced a novel particle dynamics method called Solid Electrolyte Sphere Approximation Model (SESAM). SESAM modeling targets the 1-10 µm scale structures and provides electromechanical and grain interactions for predictive design guidelines for the manufacturing of solid-state components. Parameters such as particle size and volume fraction of the constituent materials were modeled and experimentally fabricated to optimize electrochemical performance through improved microstructure design. Experimental feedback was provided through ionic and electronic conductivity assessment and structural analysis of developed materials and cell components.

battery↗

NASA NTRS1993

Effect of particle size in composite materials on radiative properties

A numerical model for the radiative properties of a composite material composed of ceramic oxide fibers and particles was developed and used to determine the effect of the size parameters of the two components. Results include the computed phase functions for the zirconia and silica composite materials, showing the location and strength of the strong forward-scattering peak. The phase function and the optical properties of the composite are strongly influenced by the particle size parameter through the fiber or particle diameter and the wavelength, the material, and the mixture fraction.

Lee, Siu-Chun↗

NASA NTRS2015

Early Size Distributions of Chondrule Subgroups Overprinted by the Final Accumulation Process of Particle Components in Allende

Populations of compositionally distinct particles are fundamental components of undifferentiated chondritic meteorites. Many theories explain the formation of chondrites, one class of which includes mechanisms for sorting the component particles in the solar nebula prior to their accretion. Mechanisms include sorting by mass, turbulent concentration, X-winds, and photophoresis, which will produce characteristic distributions of observable properties such as particle size. Distinguishing processes that occur in specific astrophysical environments requires characterization of particle types, which include refractory Ca-Al-rich Inclusions (CAIs) and less-refractory chondrules. Previous investigations of modal abundances of CAIs and chondrules exist, but differences within and between these two groups, both of which are made up of diverse subgroups with different thermal histories and chemical compositions, remain mostly unstudied. The presence of rims, a significant event occurring after the formation of at least some chondrules, have also yet to be considered with respect to sorting. Here we present the sizes of CAIs and chondrules in Allende with attention to the smallest sizes, subgroups, and particle rims.

McCain, K. A.↗

NASA NTRS1996

The Size Distribution of Stardust Injected into the ISM

A multi-component method for the description of the evolution of the grain size distribution in consideration of a size dependent grain drift and growth rate is applied in order to model dust driven winds around cool C-stars. Grain drift introduces several modifications concerning dust growth: on one hand the residence time in the region of efficient growth is reduced, on the other hand the growth efficiency is higher due to an increased collisional rate. For carbon grains the surface density of radical sites is increased, but on the other hand there is a reduction of the sticking efficiency of the growth species for drift velocities larger than a few km/s. It is found that the consideration of drift results in a considerable distortion of the size distribution as compared to the case of zero drift velocity. Generally, there are less, but larger grains if drift is included.

Krueger, D.↗

NASA NTRS2016

NDARC NASA Design and Analysis of Rotorcraft - Input, Appendix 4

The NDARC code performs design and analysis tasks. The design task involves sizing the rotorcraft to satisfy specified design conditions and missions. The analysis tasks can include off-design mission performance analysis, flight performance calculation for point operating conditions, and generation of subsystem or component performance maps. The principal tasks (sizing, mission analysis, flight performance analysis) are shown in the figure as boxes with heavy borders. Heavy arrows show control of subordinate tasks. The aircraft description consists of all the information, input and derived, that denes the aircraft. The aircraft consists of a set of components, including fuselage, rotors, wings, tails, and propulsion. This information can be the result of the sizing task; can come entirely from input, for a fixed model; or can come from the sizing task in a previous case or previous job. The aircraft description information is available to all tasks and all solutions. The sizing task determines the dimensions, power, and weight of a rotorcraft that can perform a specified set of design conditions and missions. The aircraft size is characterized by parameters such as design gross weight, weight empty, rotor radius, and engine power available. The relations between dimensions, power, and weight generally require an iterative solution. From the design flight conditions and missions, the task can determine the total engine power or the rotor radius (or both power and radius can be fixed), as well as the design gross weight, maximum takeoff weight, drive system torque limit, and fuel tank capacity. For each propulsion group, the engine power or the rotor radius can be sized. Missions are defined for the sizing task, and for the mission performance analysis. A mission consists of a number of mission segments, for which time, distance, and fuel burn are evaluated. For the sizing task, certain missions are designated to be used for design gross weight calculations; for transmission sizing; and for fuel tank sizing. The mission parameters include mission takeoff gross weight and useful load. For specified takeoff fuel weight with adjustable segments, the mission time or distance is adjusted so the fuel required for the mission equals the takeoff fuel weight. The mission iteration is on fuel weight or energy. Flight conditions are specified for the sizing task, and for the flight performance analysis. For the sizing task, certain flight conditions are designated to be used for design gross weight calculations; for transmission sizing; for maximum takeoff weight calculations; and for anti-torque or auxiliary thrust rotor sizing. The flight condition parameters include gross weight and useful load. For flight conditions and mission takeoff, the gross weight can be maximized, such that the power required equals the power available. A flight state is defined for each mission segment and each flight condition. The aircraft performance can be analyzed for the specified state, or a maximum effort performance can be identified. The maximum effort is specified in terms of a quantity such as best endurance or best range, and a variable such as speed, rate of climb, or altitude.

Rotorcraft Input↗

NASA NTRS2011

Spacecraft Environment Interactions

As electronic components have grown smaller in size and power and have increased in complexity, their enhanced sensitivity to the space radiation environment and its effects has become a major source of concern for the spacecraft engineer. As a result, the description of the sources of space radiation, the determination of how that radiation propagates through material, and, ultimately, how radiation affects specific circuit components are primary considerations in the design of modern spacecraft. The objective of this paper will be to address the first 2 aspects of the radiation problem. This will be accomplished by first reviewing the natural and man-made space radiation environments. These environments include both the particulate and, where applicable, the electromagnetic (i.e., photon) environment. As the "ambient" environment is typically only relevant to the outer surface of a space vehicle, it will be necessary to treat the propagation of the external environment through the complex surrounding structures to the point inside the spacecraft where knowledge of the internal radiation environment is required. While it will not be possible to treat in detail all aspects of the problem of the radiation environment within a spacecraft, by dividing the problem into these parts-external environment, propagation, and internal environment-a basis for understanding the practical process of protecting a spacecraft from radiation will be established. The consequences of this environment will be discussed by the other presenters at this seminar.

radiation↗

NASA NTRS1980

Flexible materials technology

A survey of all presently defined or proposed large space systems indicated an ever increasing demand for flexible components and materials, primarily as a result of the widening disparity between the stowage space of launch vehicles and the size of advanced systems. Typical flexible components and material requirements were identified on the basis of recurrence and/or functional commonality. This was followed by the evaluation of candidate materials and the search for material capabilities which promise to satisfy the postulated requirements. Particular attention was placed on thin films, and on the requirements of deployable antennas. The assessment of the performance of specific materials was based primarily on the failure mode, derived from a detailed failure analysis. In view of extensive on going work on thermal and environmental degradation effects, prime emphasis was placed on the assessment of the performance loss by meteoroid damage. Quantitative data were generated for tension members and antenna reflector materials. A methodology was developed for the representation of the overall materials performance as related to systems service life. A number of promising new concepts for flexible materials were identified.

Steurer, W. H.↗

NASA NTRS1988

Fuel-injector/air-swirl characterization

Experimental data on the characteristics of the spray produced by a gas-turbine engine airblast fuel injector are reported. The data acquired include the mass-flux distribution measured by use of a high-resolution spray patternator; the gas-phase velocity field measured by use of a two-component laser Doppler velocimeter, and the liquid droplet size and velocity distributions measured by use of a single-component phase-Doppler anemometer. The data are intended for use in assessments of two-phase flow computational methods as applied to combustor design procedures.

Mcvey, J. B.↗

NASA NTRS1988

Application of advanced diagnostics to airblast injector flows

Experimental data on the characteristics of the spray produced by a gas-turbine engine airblast fuel injector are reported. The data acquired include the mass-flux distribution, measured by use of a high-resolution spray patternator; the gas-phase velocity field, measured by use of a two-component laser Doppler velocimeter, and the liquid droplet size and velocity distribution, measured by use of a single-component phase-Doppler anemometer. The data are intended for use in assessments of two-phase flow computational methods as applied to combustor design procedures.

Mcvey, John B.↗

NASA NTRS1994

Effect of power system technology and mission requirements on high altitude long endurance aircraft

An analysis was performed to determine how various power system components and mission requirements affect the sizing of a solar powered long endurance aircraft. The aircraft power system consists of photovoltaic cells and a regenerative fuel cell. Various characteristics of these components, such as PV cell type, PV cell mass, PV cell efficiency, fuel cell efficiency, and fuel cell specific mass, were varied to determine what effect they had on the aircraft sizing for a given mission. Mission parameters, such as time of year, flight altitude, flight latitude, and payload mass and power, were also altered to determine how mission constraints affect the aircraft sizing. An aircraft analysis method which determines the aircraft configuration, aspect ratio, wing area, and total mass, for maximum endurance or minimum required power based on the stated power system and mission parameters is presented. The results indicate that, for the power system, the greatest benefit can be gained by increasing the fuel cell specific energy. Mission requirements also substantially affect the aircraft size. By limiting the time of year the aircraft is required to fly at high northern or southern latitudes, a significant reduction in aircraft size or increase in payload capacity can be achieved.

Colozza, Anthony J.↗

NASA NTRS1973

Aerosol physical properties from satellite horizon inversion

The feasibility is investigated of determining the physical properties of aerosols globally in the altitude region of 10 to 100 km from a satellite horizon scanning experiment. The investigation utilizes a horizon inversion technique previously developed and extended. Aerosol physical properties such as number density, size distribution, and the real and imaginary components of the index of refraction are demonstrated to be invertible in the aerosol size ranges (0.01-0.1 microns), (0.1-1.0 microns), (1.0-10 microns). Extensions of previously developed radiative transfer models and recursive inversion algorithms are displayed.

Gray, C. R.↗