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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 NTRS1991

Adsorbent testing and mathematical modeling of a solid amine regenerative CO2 and H2O removal system

The paper examines the design and the construction details of the test bed built for testing a solid-amine-based Regenerable CO2 Removal System (RCRS) built at the NASA/Johnson Space Center for the extended Orbiter missions. The results of tests are presented, including those for the adsorption breakthrough and the adsorption and desorption of CO2 and H2O vapor. A model for predicting the performance of regenerative CO2 and H2O vapor adsorption of the solid amine system under various operating conditions was developed in parallel with the testing of the test stand, using the coefficient of mass transfer calculated from test results. The results of simulations are shown to predict the adsorption performance of the Extended Duration Orbiter test bed fairly well. For the application to the RCRS at various operating conditions the model has to be modified.

Jeng, F. F.↗
NASA NTRS2010

Predicting the Dynamic Crushing Response of a Composite Honeycomb Energy Absorber Using Solid-Element-Based Models in LS-DYNA

This paper describes an analytical study that was performed as part of the development of an externally deployable energy absorber (DEA) concept. The concept consists of a composite honeycomb structure that can be stowed until needed to provide energy attenuation during a crash event, much like an external airbag system. One goal of the DEA development project was to generate a robust and reliable Finite Element Model (FEM) of the DEA that could be used to accurately predict its crush response under dynamic loading. The results of dynamic crush tests of 50-, 104-, and 68-cell DEA components are presented, and compared with simulation results from a solid-element FEM. Simulations of the FEM were performed in LS-DYNA(Registered TradeMark) to compare the capabilities of three different material models: MAT 63 (crushable foam), MAT 26 (honeycomb), and MAT 126 (modified honeycomb). These material models are evaluated to determine if they can be used to accurately predict both the uniform crushing and final compaction phases of the DEA for normal and off-axis loading conditions

Jackson, Karen E.↗
NASA NTRS1987

Shape design sensitivity analysis and optimization of three dimensional elastic solids using geometric modeling and automatic regridding

An automatic regridding method and a three dimensional shape design parameterization technique were constructed and integrated into a unified theory of shape design sensitivity analysis. An algorithm was developed for general shape design sensitivity analysis of three dimensional eleastic solids. Numerical implementation of this shape design sensitivity analysis method was carried out using the finite element code ANSYS. The unified theory of shape design sensitivity analysis uses the material derivative of continuum mechanics with a design velocity field that represents shape change effects over the structural design. Automatic regridding methods were developed by generating a domain velocity field with boundary displacement method. Shape design parameterization for three dimensional surface design problems was illustrated using a Bezier surface with boundary perturbations that depend linearly on the perturbation of design parameters. A linearization method of optimization, LINRM, was used to obtain optimum shapes. Three examples from different engineering disciplines were investigated to demonstrate the accuracy and versatility of this shape design sensitivity analysis method.

Yao, Tse-Min↗
NASA NTRS2017

Intermediate Fidelity Solid State Recorder Modeling for NISAR

At 26Tb/day return average, NISAR (National Aero- nautics and Space Administration (NASA) and the In- dian Space Research Organization (ISRO) Synthetic Aperture Radar) will stress ground station facilities with a variable cadence of data generation observing nearly all of earth's land and ice to produce global time- series maps of cryospheric, solid-Earth and ecosystem phenomena. Between the instrument data generation source and downlink sink lies the primary science data bu er, the SSR (Solid State Recorder). The SSR has deferred, discrete le deletion events that occur only after a le is played back to all required ground segments (sometimes both NASA and ISRO). A forward dispatch, advancing frontier repropagation playback scheduler is proposed as a model of the SSR's greedy playback scheduling behavior. Schedules based on the existing low delity model and new intermediate delity model are compared to assess the impact of deferred, discrete deletion on planning. The low delity model is found to produce unfeasible schedules that exceed SSR capacity, causing 3.87% of all observations in a 12 day simulation to be removed by repair actions.

Doubleday, Joshua R.↗
NASA NTRS1975

Solid state convection models of lunar internal temperature

Thermal models of the Moon were made which include cooling by subsolidus creep and consideration of the creep behavior of geologic material. Measurements from the Apollo program on seismic velocities, electrical conductivity of the Moon's interior, and heat flux at two locations were used in the calculations. Estimates of 1500 to 1600 K were calculated for the temperature, and one sextillion to ten sextillion sq cm/sec were calcualted for the viscosity of the deep lunar interior.

Schubert, G.↗
NASA NTRS1980

Solid-state switch modeling

A model for predicting voltages and currents of passive loads during turn on and turn off of remote power controllers is presented. The model is concerned with two devices, a five ampere device and a twenty ampere device. The model is presented as a general circuit diagram. The load current is determined by the load parameters and the conditions at switching and the steady state conditions are reached according to time constants determined by the load. The model is used to analyze the turn on and turn off conditions of certain loads including a R-C load and a R-L load.

Raburn, W. D.↗
NASA NTRS1980

An idealized model of homogeneous solid propellant combustion

The idealization of solid propellant combustion which consists of a single condensed-phase reaction and a single gas-phase reaction is discussed. A limiting-case solution to the gas-phase conservation equations is developed and tested by comparison with transformed thermocouple data. Closed-form expressions are derived for the burning rate and temperature sensitivity. Both quantities are linked explicitly to the solid and gas activation energies. It is concluded that the combustion phenomenology associated with the above idealization is still not fully understood. It is suggested that a careful study of the various limiting-case solutions tempered by a small set of numerical benchmark calculations might further such understanding.

Miller, M. S.↗
NASA NTRS1988

Analysis and test of a space truss foldable hinge

The Mini-Mast is a 20-meter long deployable, three-longeron, truss-beam being used to develop analytical and experimental methods for predicting the physical behavior of large space structures. With 57 corner-body hinges and 54 mid-body hinges, the Mini-Mast is highly joint-dominated, necessitating inclusion of the compliance of the joints in analytical models. This study demonstrates an approach for calculating the stiffness properties of a complicated hinge called the mid-body hinge. The process includes detailed modeling with solid-body modeling software and the use of finite element analysis. Load-deflection tests were conducted to determine the axial stiffness of the mid-body hinge. This is compared to the axial stiffness value determined from a finite element analysis.

Nimmo, N. A.↗
NASA NTRS1976

Force test of a 0.88 percent scale 142-inch diameter solid rocket booster (MSFC model number 461) in the NASA/MSFC high Reynolds number wind tunnel (SA13F)

The results are presented of a force test of a .88 percent scale model of the 142 inch solid rocket booster without protuberances, conducted in the MSFC high Reynolds number wind tunnel. The objective of this test was to obtain aerodynamic force data over a large range of Reynolds numbers. The test was conducted over a Mach number range from 0.4 to 3.5. Reynolds numbers based on model diameter (1.25 inches) ranged from .75 million to 13.5 million. The angle of attack range was from 35 to 145 degrees.

Johnson, J. D.↗
NASA NTRS1976

Development of a solid propellant viscoelastic dynamic model

The results of a one year study to develop a dynamic response model for the Space Shuttle Solid Rocket Motor (SRM) propellant are presented. An extensive literature survey was conducted, from which it was concluded that the only significant variables affecting the dynamic response of the SRM propellant are temperature and frequency. Based on this study, and experimental data on propellants related to the SRM propellant, a dynamic constitutive model was developed in the form of a simple power law with temperature incorporated in the form of a modified power law. A computer program was generated which performs a least-squares curve-fit of laboratory data to determine the model parameters and it calculates dynamic moduli at any desired temperature and frequency. Additional studies investigated dynamic scaling laws and the extent of coupling between the SRM propellant and motor cases. It was found, in agreement with other investigations, that the propellant provides all of the mass and damping characteristics whereas the case provides all of the stiffness.

Hufferd, W. L.↗
NASA NTRS1979

Landsat test of diffuse reflectance models for aquatic suspended solids measurement

Landsat radiance data were used to test mathematical models relating diffuse reflectance to aquatic suspended solids concentration. Digital CCT data for Landsat passes over the Bay of Fundy, Nova Scotia were analyzed on a General Electric Co. Image 100 multispectral analysis system. Three data sets were studied separately and together in all combinations with and without solar angle correction. Statistical analysis and chromaticity analysis show that a nonlinear relationship between Landsat radiance and suspended solids concentration is better at curve-fitting than a linear relationship. In particular, the quasi-single-scattering diffuse reflectance model developed by Gordon and coworkers is corroborated. The Gordon model applied to 33 points of MSS 5 data combined from three dates produced r = 0.98.

Munday, J. C., Jr.↗