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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 1,009 records · Page 56
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

Towards a Decision Support System for Space Flight Operations

The Mission Operations Directorate (MOD) at the Johnson Space Center (JSC) has put in place a Model Based Systems Engineering (MBSE) technological framework for the development and execution of the Flight Production Process (FPP). This framework has provided much added value and return on investment to date. This paper describes a vision for a model based Decision Support System (DSS) for the development and execution of the FPP and its design and development process. The envisioned system extends the existing MBSE methodology and technological framework which is currently in use. The MBSE technological framework currently in place enables the systematic collection and integration of data required for building an FPP model for a diverse set of missions. This framework includes the technology, people and processes required for rapid development of architectural artifacts. It is used to build a feasible FPP model for the first flight of spacecraft and for recurrent flights throughout the life of the program. This model greatly enhances our ability to effectively engage with a new customer. It provides a preliminary work breakdown structure, data flow information and a master schedule based on its existing knowledge base. These artifacts are then refined and iterated upon with the customer for the development of a robust end-to-end, high-level integrated master schedule and its associated dependencies. The vision is to enhance this framework to enable its application for uncertainty management, decision support and optimization of the design and execution of the FPP by the program. Furthermore, this enhanced framework will enable the agile response and redesign of the FPP based on observed system behavior. The discrepancy of the anticipated system behavior and the observed behavior may be due to the processing of tasks internally, or due to external factors such as changes in program requirements or conditions associated with other organizations that are outside of MOD. The paper provides a roadmap for the three increments of this vision. These increments include (1) hardware and software system components and interfaces with the NASA ground system, (2) uncertainty management and (3) re-planning and automated execution. Each of these increments provide value independently; but some may also enable building of a subsequent increment.

Meshkat, Leila↗
NASA NTRS2013

Towards a decision support system for space flight operations

The Mission Operations Directorate (MOD) at the Johnson Space Center (JSC) has put in place a Model Based Systems Engineering (MBSE) technological framework for the development and execution of the Flight Production Process (FPP). This framework has provided much added value and return on investment to date. This paper describes a vision for a model based Decision Support System (DSS) for the development and execution of the FPP and its design and development process. The envisioned system extends the existing MBSE methodology and technological framework which is currently in use. The MBSE technological framework currently in place enables the systematic collection and integration of data required for building an FPP model for a diverse set of missions. This framework includes the technology, people and processes required for rapid development of architectural artifacts. It is used to build a feasible FPP model for the first flight of spacecraft and for recurrent flights throughout the life of the program. This model greatly enhances our ability to effectively engage with a new customer. It provides a preliminary work breakdown structure, data flow information and a master schedule based on its existing knowledge base. These artifacts are then refined and iterated upon with the customer for the development of a robust end-to-end, high-level integrated master schedule and its associated dependencies. The vision is to enhance this framework to enable its application for uncertainty management, decision support and optimization of the design and execution of the FPP by the program. Furthermore, this enhanced framework will enable the agile response and redesign of the FPP based on observed system behavior. The differences between the anticipated system behavior and the observed behavior may be due to the processing of tasks internally, or due to external factors such as changes in program requirements or conditions associated with other organizations that are outside of MOD. The paper provides a roadmap for the four increments of this vision. These increments include (1) the existing capabilities (2) hardware and software system components and interfaces with the NASA ground system, (3) uncertainty management and (4) re-planning and automated execution. Each of these increments provides value independently; but some may also enable building of a subsequent increment.

Ruszkowski, James↗
NASA NTRS1977

Rocket exhaust effluent modeling for tropospheric air quality and environmental assessments

The various techniques for diffusion predictions to support air quality predictions and environmental assessments for aerospace applications are discussed in terms of limitations imposed by atmospheric data. This affords an introduction to the rationale behind the selection of the National Aeronautics and Space Administration (NASA)/Marshall Space Flight Center (MSFC) Rocket Exhaust Effluent Diffusion (REED) program. The models utilized in the NASA/MSFC REED program are explained. This program is then evaluated in terms of some results from a joint MSFC/Langley Research Center/Kennedy Space Center Titan Exhaust Effluent Prediction and Monitoring Program.

Stephens, J. B.↗
NASA NTRS1992

Systems level polarization modeling of multispectral space sensors

The 2-percent polarization sensitivity specification in many of NASA's Earth Observing System sensors has motivated Santa Barbara Research Center (SBRC) to develop computer programs that model the polarization characteristics of optical systems. In support of the Moderate Resolution Imaging Spectroradiometer program, SBRC has developed an analytical tool which unites the completed 3D lens design and coating designs to accurately predict an optical system's polarization characterization compensators, nonnormal incidence reflection and transmission from dichroic beam splitters and protected silver mirrors are analyzed without the need for proprietary coating prescriptions. The phenomenon of diattenuation and phase change are treated using the Jones matrix formalism.

Wells, Conrad↗
NASA NTRS1976

Investigation of aeroelastic stability phenomena of a helicopter by in-flight shake test

The analytical capability of the helicopter stability program is discussed. The parameters which are found to be critical to the air resonance characteristics of the soft in-plane hingeless rotor systems are detailed. A summary of two model test programs, a 1/13.8 Froude-scaled BO-105 model and a 1.67 meter (5.5 foot) diameter Froude-scaled YUH-61A model, are presented with emphasis on the selection of the final parameters which were incorporated in the full scale YUH-61A helicopter. Model test data for this configuration are shown. The actual test results of the YUH-61A air resonance in-flight shake test stability are presented. Included are a concise description of the test setup, which employs the Grumman Automated Telemetry System (ATS), the test technique for recording in-flight stability, and the test procedure used to demonstrate favorable stability characteristics with no in-plane damping augmentation (lag damper removed). The data illustrating the stability trend of air resonance with forward speed and the stability trend of ground resonance for percent airborne are presented.

Miao, W. L.↗
NASA NTRS1994

Ten-year ground exposure of composite materials used on the Bell Model 206L helicopter flight service program

Residual strength results are presented for four composite material systems that have been exposed for up to 10 years to the environment at five different locations on the North American continent. The exposure locations are near where the Bell Model 206L helicopters, which participated in a flight service program sponsored by NASA Langley Research Center and the U.S. Army, were flying in daily commercial service. The composite material systems are (1) Kevlar-49 fabric/F-185 epoxy; (2) Kevlar-49 fabric/LRF-277 epoxy; (3) Kevlar-49 fabric/CE-306 epoxy; and (4) T-300 graphite/E-788 epoxy. Six replicates of each material were removed and tested after 1, 3, 5, 7, and 10 years of exposure. The average baseline strength was determined from testing six as-fabricated specimens. More than 1700 specimens have been tested. All specimens that were tested to determine their strength were painted with a polyurethane paint. Each set of specimens also included an unpainted panel for observing the weathering effects on the composite materials. A statistically based procedure has been used to determine the strength value above which at least 90 percent of the population is expected to fall with a 95-percent confidence level. The computed compression strengths are 80 to 90 percent of the baseline (no-exposure) strengths. The resulting compression strengths are approximately 8 percent below the population mean strengths. The computed short-beam-shear strengths are 83 to 92 percent of the baseline (no-exposure) strengths. The computed tension strength of all materials is 93 to 97 percent of the baseline (no-exposure) strengths.

Baker, Donald J.↗
DOE OSTI2022

HOMP (Hybrid Operation and Maintenance Platform) [SWR-22-81]

The HOMP software module is contained within NREL's Hybrid Optimization and Performance Platform (HOPP) at this URL: https://github.com/NREL/HOPP/tree/feature/HOMP. HOMP is a python-based software module which can be used concurrently with the Hybrid Optimization and Performance Platform (HOPP) to model, simulate, and optimize degradation, reliability, and operations and maintenance of hybrid power plant components. The program currently models lithium ion battery, PEM electrolyzer, wind turbine, and solar PV array components, which enables users to understand the design and operation tradeoffs of hybrid power plants. For instance, HOMP enables users to answer questions like: how large does a battery bank need to be to achieve optimal charge/discharge rates for performance and reliability? How does plant design change for different objectives (e.g., profit versus resilience)? Under what conditions is it better to produce electricity versus hydrogen? How do we optimally control hybrid power plants to reduce downtime and increase performance?

Clark, Caitlyn↗
NASA NTRS1979

Performance characteristics of a wedge nozzle installed on an F-18 propulsion wind tunnel model

The results of two-dimensional wedge non-axisymmetric nozzle (2D-AIN) tests to determine its performance relative to the baseline axisymmetric nozzle using an F-18 jet effects wind tunnel model are presented. Configurations and test conditions simulated forward thrust-minus drag, thrust vectoring/induced lift, and thrust reversing flight conditions from Mach .6 to 1.20 and attack angles up to 10 degrees. Results of the model test program indicate that non-axisymmetric nozzles can be installed on a twin engine fighter aircraft model with equivalent thrust minus drag performance as the baseline axisymmetric nozzles. Thrust vectoring capability of the non-axisymmetric nozzles provided significant jet-induced lift on the nozzle/aftbody and horizontal tail surfaces. Thrust reversing panels deployed from the 2D-AIN centerbody wedge were very effective for static and inflight operation

Petit, J. E.↗
NASA NTRS1981

Computerized symbolic manipulation in nonlinear finite element analysis

The potential of using computerized symbolic manipulation in the development of nonlinear finite elements is discussed. Three tasks which can be efficiently performed using computerized symbolic manipulation are identified: (1) generation of algebraic expressions for the stiffness coefficients of nonlinear finite elements, (2) generation of FORTRAN source code for numerical evaluation of stiffness coefficients, and (3) checking the correctness of the FORTRAN statements for the arrays of coefficients. The symbolic and algebraic manipulation system MACSYMA is used in the present study. Two sample MACSYMA programs are presented for the development of the nonlinear stiffness coefficients of two-dimensional, shear-flexible, doubly-curved deep shell elements. The first program is for displacement models and the second program is for mixed models with discontinuous stress-resultant fields at interelement boundaries.

Noor, A. K.↗
NASA NTRS2003

Foam on Tile Impact Modeling for the Space Shuttle Program

Following the breakup of the Space Shuttle Columbia during reentry a NASA-wide investigation team was formed to examine the probable damage inflicted on Orbiter Thermal Protection System (TPS) elements by impact of External Tank insulating foam projectiles. Our team was to apply rigorous, physics-based analysis techniques to help determine parameters of interest for an experimental test program, utilize validated codes to investigate the full range of impact scenarios, and use analysis derived models to predict aero-thermal-structural responses to entry conditions. We were to operate on a non-interference basis with the j Team, and were to supply significant findings to that team and to the Orbiter Vehicle Engineering Working Group, being responsive to any solicitations for support from these entities. The authors formed a working sub-group within the larger team to apply the Smooth Particle Hydrodynamics code SPHC to the damage estimation problem. Numerical models of the LI-900 TPS tiles and of the BX-250 foam were constructed and used as inputs into the code. Material properties needed to properly model the tiles and foam were obtained from other working sub-groups who performed tests on these items for this purpose. Two- and three- dimensional models of the tiles were constructed, including the glass outer layer, the densified lower layer of LI-900 insulation, the Nomex felt Strain Isolation Pad (SIP) mounting layer, and the underlying aluminum 2024 vehicle skin. A model for the BX-250 foam including porous compression, elastic rebound, and surface erosion was developed. Code results for the tile damage and foam behavior were extensively validated through comparison with the Southwest Research Institute (SwRI) foam-on-tile impact experiments carried out in 1999. These tests involved small projectiles striking individual tiles and small tile arrays. Following code and model validation we simulated impacts of larger ET foam projectiles on the TPS tile systems used on the wings of the orbiter. Tiles used on the Wing Acreage, the Main Landing Gear Door, and the Carrier Panels near the front edge of the wing were modeled. Foam impacts shot for the CAB investigation were modeled, as well as impacts at larger angles, including rapid rotation of the projectile, and with varying foam properties. General results suggest that foam impacts on tiles at about 500 mph could cause appreciable damage if the impact angle is greater than about 20 degrees. Some variations of the foam properties, such as increased brittleness or increased density could increase damage in some cases. Rapid (17 rps) rotation failed to increase the damage for the two cases considered. This does not rule out other cases in which the rotational energy might lead to an increase in tile damage, but suggests that in most cases rotation will not be an important factor. Similar models will be applied for other impacting materials, other velocities, and other geometries as part of the Return to Flight process.

Stellingwerf, R. F.↗
NASA NTRS1978

JPL Energy Consumption Program (ECP) documentation: A computer model simulating heating, cooling and energy loads in buildings

The engineering manual provides a complete companion documentation about the structure of the main program and subroutines, the preparation of input data, the interpretation of output results, access and use of the program, and the detailed description of all the analytic, logical expressions and flow charts used in computations and program structure. A numerical example is provided and solved completely to show the sequence of computations followed. The program is carefully structured to reduce both user's time and costs without sacrificing accuracy. The user would expect a cost of CPU time of approximately $5.00 per building zone excluding printing costs. The accuracy, on the other hand, measured by deviation of simulated consumption from watt-hour meter readings, was found by many simulation tests not to exceed + or - 10 percent margin.

Lansing, F. L.↗
NASA NTRS1986

Thermal barrier coating life-prediction model development

The program focuses on predicting the lives of two types of strain-tolerant and oxidation-resistant thermal barrier coating (TBC) systems that are produced by commercial coating suppliers to the gas turbine industry. The plasma-sprayed TBC system, composed of a low-pressure plasma-spray (LPPS) or an argon shrouded plasma-spray (ASPS) applied oxidation resistant NiCrAlY or (CoNiCrAlY) bond coating and an air-plasma-sprayed yttria partially stabilized zirconia insulative layer, is applied by both Chromalloy, Klock, and Union Carbide. The second type of TBS is applied by the electron beam-physical vapor deposition (EB-PVD) process by Temescal. The second year of the program was focused on specimen procurement, TMC system characterization, nondestructive evaluation methods, life prediction model development, and TFE731 engine testing of thermal barrier coated blades. Materials testing is approaching completion. Thermomechanical characterization of the TBC systems, with toughness, and spalling strain tests, was completed. Thermochemical testing is approximately two-thirds complete. Preliminary materials life models for the bond coating oxidation and zirconia sintering failure modes were developed. Integration of these life models with airfoil component analysis methods is in progress. Testing of high pressure turbine blades coated with the program TBS systems is in progress in a TFE731 turbofan engine. Eddy current technology feasibility was established with respect to nondestructively measuring zirconia layer thickness of a TBC system.

Strangman, T. E.↗
NASA NTRS1984

Global Scale Atmospheric Processes Research Program Review

Global modeling; satellite data assimilation and initialization; simulation of future observing systems; model and observed energetics; dynamics of planetary waves; First Global Atmospheric Research Program Global Experiment (FGGE) diagnosis studies; and National Research Council Research Associateship Program are discussed.

Worley, B. A.↗
DOE OSTI2022

Fuel Performance Modeling Plan to Support the Advance Gas Reactor Program

This report documents the current status of the fuel performance modeling initiative to support the Advanced Gas Reactor (AGR) program in the development of tristructural isotropic (TRISO) coated fuel particles. A brief summary of the modeling codes that have been developed to support TRISO modeling is included along with a summary of the behavior of fuel particles during irradiation and the modeling used to capture these effects. In addition, this report identifies further modeling and material property needs that have been identified for further development based on experience from previously performed AGR experiments. In general, the remaining activities to support fuel performance modeling for the AGR program include continued AGR experiment support for AGR-3/4 and AGR-5/6/7 as well as modeling improvements identified throughout the course of the program. These modeling improvements can be summarized as the following: Fission product transport Thermomechanical particle behavior Additional modeling needs may be identified during the processing the data collected during the AGR post-irradiation examination (PIE) campaign and may lead to further modeling improvements that are not included in this report.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS1975

Importance of helicopter dynamics to the mathematical model of the helicopter

A mathematical model of the helicopter requires appropriate representation of the constituent elements of rotor dynamics. General-purpose programs that model a variety of configurations for a broad range of operating conditions result in varying and incompatible levels of sophistication. Analysis of specific dynamic problems facilitates the identification of configuration parameters which determine system behavior. For the present analysis, the nonlinear equations of a torsionally rigid hingeless rotor are linearized about an equilibrium condition to determine flap-lag stability characteristics in hover. A collocation method was used to obtain the coupled natural frequencies and modes. These modes allow exact treatment of the effect of elastic coupling which more than compensates for the destabilizing inertial coupling. The sensitivity of damping to the number of modes was found to be small, and reasonable accuracy was obtained the first flapwise and edgewise coupled modes. The range of destabilizing precone was found to be small.

White, W. F., Jr.↗
NASA NTRS1983

NASTRAN Structural Model for the Large 64-meter Antenna Pedestal, Part 1

Static analysis and a computer structural model for the large 64-m antenna pedestal are developed using the MSC version of the NASTRAN program. This model was necessary to conduct a variety of hydrostatic bearing rehabilitation studies. The results obtained from the model show that the top surface deflections due to pad loads are in good agreement with the results previously obtained from a simplified "shortcut' analytical model, and also in agreement with field measurements. In addition, the displacement and force distributions as well as the state of stress and strain are obtained.

Chian, C. T.↗
NASA NTRS2008

Toward a Formal Evaluation of Refactorings

Refactoring is a software development strategy that characteristically alters the syntactic structure of a program without changing its external behavior [2]. In this talk we present a methodology for extracting formal models from programs in order to evaluate how incremental refactorings affect the verifiability of their structural specifications. We envision that this same technique may be applicable to other types of properties such as those that concern the design and maintenance of safety-critical systems.

Paul, John↗
NASA NTRS2001

A Wind-Tunnel Parametric Investigation of Tiltrotor Whirl-Flutter Stability Boundaries

A wind-tunnel investigation of tiltrotor whirl-flutter stability boundaries has been conducted on a 1/5-size semispan tiltrotor model known as the Wing and Rotor Aeroelastic Test System (WRATS) in the NASA-Langley Transonic Dynamics Tunnel as part of a joint NASA/Army/Bell Helicopter Textron, Inc. (BHTI) research program. The model was first developed by BHTI as part of the JVX (V-22) research and development program in the 1980's and was recently modified to incorporate a hydraulically-actuated swashplate control system for use in active controls research. The modifications have changed the model's pylon mass properties sufficiently to warrant testing to re-establish its baseline stability boundaries. A parametric investigation of the effect of rotor design variables on stability was also conducted. The model was tested in both the on-downstop and off-downstop configurations, at cruise flight and hover rotor rotational speeds, and in both air and heavy gas (R-134a) test mediums. Heavy gas testing was conducted to quantify Mach number compressibility effects on tiltrotor stability. Experimental baseline stability boundaries in air are presented with comparisons to results from parametric variations of rotor pitch-flap coupling and control system stiffness. Increasing the rotor pitch-flap coupling (delta(sub 3) more negative) was found to have a destabilizing effect on stability, while a reduction in control system stiffness was found to have little effect on whirl-flutter stability. Results indicate that testing in R-134a, and thus matching full-scale tip Mach number, has a destabilizing effect, which demonstrates that whirl-flutter stability boundaries in air are unconservative.

Piatak, David J.↗