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Results for “Power modeling”

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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Synchronous orbit power technology needs

An attempt is made to define the needs for future geosynchronous spacecraft power subsystem components, including power generation, energy storage, and power processing. Three projected models (a mission model, an orbit transfer vehicle model, and a mass model) for power subsystem components are used to define power requirements and mass limitations for future spacecraft. Based upon these models, the power subsystems for a 10-kW, 10-year-life, dedicated spacecraft and for a 20-kW, 20-year-life multimission platform are analyzed to establish power density requirements for orbit transfer vehicles. Comparison of these requirements to state-of-the-art (Intelsat 5) design values shows that major improvements, by a factor of 2 or more, are needed to accomplish the near term missions.

Slifer, L. W., Jr.↗
NASA NTRS1993

Computational flowfields for static testing of powered hypersonic aftbody models

Two-dimensional CFD analyses are presented related to the ground testing of hypersonic, air-breathing models which feature scramjet exhaust flow simulation. CFD analysis indicates that it is possible to test aftbody powered hypersonic airbreather configurations in a static, pumped-down environment to obtain aftbody aerodynamic performance data.

Huebner, Lawrence D.↗
NASA NTRS2011

Electromagnetic Launch Vehicle Fairing and Acoustic Blanket Model of Received Power Using FEKO

Evaluating the impact of radio frequency transmission in vehicle fairings is important to sensitive spacecraft. This paper employees the Multilevel Fast Multipole Method (MLFMM) feature of a commercial electromagnetic tool to model the fairing electromagnetic environment in the presence of an internal transmitter. This work is an extension of the perfect electric conductor model that was used to represent the bare aluminum internal fairing cavity. This fairing model includes typical acoustic blanketing commonly used in vehicle fairings. Representative material models within FEKO were successfully used to simulate the test case.

Trout, Dawn H.↗
NASA NTRS2011

Electromagnetic Launch Vehicle Fairing and Acoustic Blanket Model of Received Power Using FEKO

Evaluating the impact of radio frequency transmission in vehicle fairings is important to electromagnetically sensitive spacecraft. This study employs the multilevel fast multipole method (MLFMM) from a commercial electromagnetic tool, FEKO, to model the fairing electromagnetic environment in the presence of an internal transmitter with improved accuracy over industry applied techniques. This fairing model includes material properties representative of acoustic blanketing commonly used in vehicles. Equivalent surface material models within FEKO were successfully applied to simulate the test case. Finally, a simplified model is presented using Nicholson Ross Weir derived blanket material properties. These properties are implemented with the coated metal option to reduce the model to one layer within the accuracy of the original three layer simulation.

Trout, Dawn H.↗
NASA NTRSDate not supplied

Mass Modeling of NEP Power Conversion Concepts for Human Mars Exploration

The specific mass (mass per unit of electric power output) of an NEP power conversion system is an important metric for the performance and feasibility of a crewed NEP vehicle. This work explores a component level buildup of the specific mass for a crewed NEP vehicle. The buildup is highly parametric and avoids being tied to specific technologies where practical. This allows the specific mass to be calculated for a variety of assumptions and operating conditions and be used to optimize particular design variables or compare different system configurations. The values of specific mass are dependent on assumptions with significant uncertainty; comparison between cases and trends observed in the models are the main goal of the work presented here. To demonstrate the level of insight this type of modeling can provide, the impacts of compressor inlet temperature, turbine inlet temperature, and radiator pressure drop on specific mass are explored. In addition, the specific mass can be used to assess the benefit of separating the radiator and reactor loop from the power conversion cycle.

nep↗
NASA NTRSDate not supplied

Mass Modeling of NEP Power Conversion Concepts for Human Mars Exploration

The specific mass (mass per unit of electric power output) of an NEP power conversion system is an important metric for the performance and feasibility of a crewed NEP vehicle. This work explores a component level buildup of the specific mass for a crewed NEP vehicle. The buildup is highly parametric and avoids being tied to specific technologies where practical. This allows the specific mass to be calculated for a variety of assumptions and operating conditions and be used to optimize particular design variables or compare different system configurations. The values of specific mass are dependent on assumptions with significant uncertainty; comparison between cases and trends observed in the models are the main goal of the work presented here. To demonstrate the level of insight this type of modeling can provide, the impacts of compressor inlet temperature, turbine inlet temperature, and radiator pressure drop on specific mass are explored. In addition, the specific mass can be used to assess the benefit of separating the radiator and reactor loop from the power conversion cycle.

NEP↗
NASA NTRS1947

Flight Tests of Rocket-Powered "Tin-Can" Models of AAF Project MX-800

Flight tests were made of six noninstrumented rocket-powered "Tin Can" models of AAF Project MX-800. Velocity and drag data were obtained by use of CU Doppler radar. The existence of stability and adequate structural strength for flight near zero lift was checked by visual and photographic observation. Drag data obtained during the tests agreed reasonably well with estimates based on experimental data from NACA RM-2 rocket-powered drag research models.

Purser, Paul E.↗
NASA NTRS2001

Electrical Power Distribution and Control Modeling and Analysis

This slide presentation reviews the use of Electrical Power Distribution and Control (EPD&C) Modeling and how modeling can support analysis. The presentation discusses using the EASY5 model to simulate and analyze the Space Shuttle Electric Auxiliary Power Unit. Diagrams of the model schematics are included, as well as graphs of the battery cell impedance, hydraulic load dynamics, and EPD&C response to hydraulic load variations.

Fu, Johnny S.↗
NASA NTRS1978

Scintillation observations near the sun

Results on the electron density spectrum, the random velocity and the mean velocity of the solar wind in the region from 5 to 100 solar radii are presented. Results are based on intensity scintillations of incoherent radio sources at different locations and different radio frequencies. The shape of the electron density irregularity spectrum is shown to be well modeled by a power law in wavenumber with a slope that abruptly steepens at higher wavenumbers. This two slope power law model is shown to have a break (defined as the wavenumber of the change of slope) that increases with decreasing distance from the Sun. The fractional random velocity is shown to be insignificant at distances of greater than 40 solar radii, but shows a steady increase with decreasing solar distance inside of 40 solar radii.

Coles, W. A.↗
NASA NTRS1984

Analytical Modeling of Spacecraft Power Systems

During the 25 years of space flight with unmanned Earth orbiting satellites, there has been an evolution of power systems in three general areas. The size of power system in terms of power demand at the bus has increased frorm a few watts in the early 1960s to a few hundred watts during the 1970s. Today, the bus power requirements are typically in the .5 to 1 kw range with some mission requirements exceeding the 1 kw size. Power grounding and user isolation are major design considerations when high fidelity power is required by a user.

Ford, F. E.↗
NASA NTRS1986

X-ray spectroscopy of five BL Lacertae objects

Five X-ray bright BL Lacertae objects were observed in the energy range 0.6-4.5 keV with the solid state spectrometer (SSS) of the Einstein Observatory. The 14 SSS spectra obtained represent most of the X-ray spectra of BL Lac objects with resolution better than approximately 3. These data do not reveal the presence of large amounts of thermal gas, with upper limits for the equivalent width of individual spectral features typically less that about 100 eV. However, the SSS spectra are the first set of X-ray data to indicate low-energy absorption in excess of that caused by the cold interstellar matter in the Galaxy. Comparison with contemporaneous, lower energy X-ray data implies that this absorption does not arise in cold neutral material, but in hotter, highly ionized material, probably intrinsic to the source. All five BL Lac objects have X-ray continua that are well fitted by power-law models, with power-law energy indices usually greater than about 1. In a few cases, a flattening at higher energies is observed; these and other data suggest that two-component X-ray spectra, steep at low energies and flat at high energies, are a common feature of BL Lac objects. Three of the five sources clearly vary between SSS observations, with time scales ranging from days to years. A historical synopsis of the X-ray spectral data confirms the tendency for BL Lacertae objects to be highly variable in the X-ray band but reveals no correlation between spectral and intensity changes.

Urry, C. M.↗
NASA NTRS1986

Space power system scheduling using an expert system

A most pressing problem in space exploration is timely spacecraft power system sequence generation, which requires the scheduling of a set of loads given a set of resource constraints. This is particularly important after an anomaly or failure. This paper discusses the power scheduling problem and how the software program, Plan-It, can be used as a consultant for scheduling power system activities. Modeling of power activities, human interface, and two of the many strategies used by Plan-It are discussed. Preliminary results showing the development of a conflict-free sequence from an initial sequence with conflicts is presented. It shows that a 4-day schedule can be generated in a matter of a few minutes, which provides sufficient time in many cases to aid the crew in the replanning of loads and generation use following a failure or anomaly.

Bahrami, K. A.↗
NASA NTRS1998

Variable-Frequency QPOs from the Galactic Microquasar GRS 1915+105

We show that the galactic microquasar GRS 1915+105 exhibits quasi-periodic oscillations (QPOS) whose frequency varies continuously from 1-15 Hz, during spectrally hard dips when the source is in a flaring state. NN'e report here analyses of simultaneous energy spectra and power density spectra at 4 s intervals. The energy spectrum is well fit at each time step by an optically thick accretion disk plus power law model, while the power density spectrum consists of a varying red noise component plus the variable frequency QPO. The features of both spectra are strongly correlated with one another. The 1-15 Hz QPOs appear when the power law component becomes hard and intense, and themselves have an energy spectrum consistent with the power law component (with root mean square amplitudes as high as 10%). The frequency of the oscillations, however, is most strikingly correlated with the parameters of the thermal disk component. The tightest correlation is between QPO frequency and the disk X-ray flux. This fact indicates that the properties of the QPO are not determined by solely a disk or solely a corona.

Markwardt, Craig B.↗
NASA NTRS2001

Mathematical Modeling of Ni/H2 and Li-Ion Batteries

The modelling effort outlined in this viewgraph presentation encompasses the following topics: 1) Electrochemical Deposition of Nickel Hydroxide; 2) Deposition rates of thin films; 3) Impregnation of porous electrodes; 4) Experimental Characterization of Nickel Hydroxide; 5) Diffusion coefficients of protons; 6) Self-discharge rates (i.e., oxygen-evolution kinetics); 7) Hysteresis between charge and discharge; 8) Capacity loss on cycling; 9) Experimental Verification of the Ni/H2 Battery Model; 10) Mathematical Modeling Li-Ion Batteries; 11) Experimental Verification of the Li-Ion Battery Model; 11) Integrated Power System Models for Satellites; and 12) Experimental Verification of Integrated-Systems Model.

Weidner, John W.↗
NASA NTRS2003

A Chandra X-Ray Study of NGC 1068 IL the Luminous X-Ray Source Population

We present an analysis of the compact X-ray source population in the Seyfert 2 galaxy NGC 1068, imaged with a approx. 50 ks Chandra observation. We find a total of 84 compact sources on the S3 chip, of which 66 are located within the 25.0 B-mag/arcsec isophote of the galactic disk of NGC 1068. Spectra have been obtained for the 21 sources with at least 50 counts and modeled with both multicolor disk blackbody and power-law models. The power-law model provides the better description of the spectrum for 18 of these sources. For fainter sources, the spectral index has been estimated from the hardness ratio. Five sources have 0.4 - 8 keV intrinsic luminosities greater than 10(exp 39)ergs/ s, assuming that their emission is isotropic and that they are associated with NGC 1068. We refer to these sources as intermediate-luminosity X-ray objects (ISOs). If these five sources are X-ray binaries accreting with luminosities that are both sub-Eddington and isotropic, then the implied source masses are approx greater than 7 solar mass, and so they are inferred to be black holes. Most of the spectrally modeled sources have spectral shapes similar to Galactic black hole candidates. However, the brightest compact source in NGC 1068 has a spectrum that is much harder than that found in Galactic black hole candidates and other ISOs. The brightest source also shows large amplitude variability on both short-term and long-term timescales, with the count rate possibly decreasing by a factor of 2 in approx. 2 ks during our Chundra observation, and the source flux decreasing by a factor of 5 between our observation and the grating observations taken just over 9 months later. The ratio of the number of sources with luminosities greater than 2.1 x 10(exp 38) ergs/s in the 0.4 - 8 keV band to the rate of massive (greater than 5 solar mass) star formation is the same, to within a factor of 2, for NGC 1068, the Antennae, NGC 5194 (the main galaxy in M51), and the Circinus galaxy. This suggests that the rate of production of X-ray binaries per massive star is approximately the same for galaxies with currently active star formation, including "starbursts."

Smith, David A.↗