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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 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Influence of aluminum source and Ni/Al ratio in a batch stirred tank reactor on the structure, morphology, and electrochemical performance of Ni-rich NMA cathodes

Here, the structural, morphological, and electrochemical performance of Ni-rich LiNi 0.9 Mn 0.05 Al 0.05 O 2 (955NMA) and LiNi 0.85 Mn 0.05 Al 0.1 O 2 (85,510) cathodes strongly depends on the properties of their hydroxide precursors. Ni-Mn-Al hydroxide precursors were synthesized through controlled co-precipitation in a batch stirred tank reactor, where pH, reaction time, metal-ion feed rate, aluminum source, and aluminum concentration were systematically varied to tailor particle morphology, phase composition, and dopant distribution. Two aluminum sources, aluminum nitrate and sodium aluminate produced two distinct hydroxide precursors NMA(OH) 2 -1 and NMA(OH) 2 -2, which were lithiated to form LiNMA1 (Li 0.992 [Ni 0.905 Mn 0.049 Al 0.046 ]O 2 ) and LiNMA2 (Li 0.990 [Ni 0.850 Mn 0.047 Al 0.103 ]O 2 ). Structural and compositional analyses revealed that aluminum incorporation and phase formation in Ni–Mn–Al hydroxides are governed by local supersaturation and interfacial growth kinetics. Rapid dilute aluminum addition produced aluminum-free β-phase hydroxides, intermediate conditions generated mixed α/β phases, whereas slow concentrated dosing enabled uniform aluminum incorporation and stabilization of the β-phase structure. LiNMA1 delivers a high initial discharge capacity of 223 mAhg −1 but significant capacity fading with 67% retention after 100 cycles, associated with structural instability. In contrast, LiNMA2 delivers a lower initial capacity 172 mAhg −1 yet excellent cycling stability 91% retention, attributed to improved TM–O framework stability and reduced cation disorder.

Capacity↗
NASA NTRS1973

Effect of exhaust nozzle configuration on aerodynamic and acoustic performance of an externally blown flap system with a quiet 6:1 bypass ratio engine

A highly suppressed TF-34 engine was used to investigate engine and flap interaction noise associated with an externally blown flap STOL powered lift system. Noise, efficiency, and velocity decay characteristics of mixed and separate flow exhaust systems including convergent, co-annular, and lobed designs were determined with the engine operating alone. Noise data were then obtained for several of the exhaust configurations with the engine blowing a wing-flap segment. Noise for both the engine alone and the engine with blown flaps showed substantial differences for the various exhaust configurations tested. The differences in observed noise are related primarily to nozzle effective exhaust velocity, flap impingement velocity, and noise spectral shape.

Samanich, N. E.↗
NASA NTRS1973

Effect of exhaust nozzle configuration on aerodynamic and acoustic performance of an externally blown flap system with a quiet 6:1 bypass ratio engine

A highly suppressed TF-34 engine was used to investigate engine and flap interaction noise associated with an externally blown flap STOL powered lift system. Noise, efficiency, and velocity decay characteristics of mixed and separate flow exhaust systems including convergent, co-annular, and lobed designs were determined with the engine operating alone. Noise data were then obtained for several of the exhaust configurations with the engine blowing a wing-flap segment. Noise for both the engine alone and the engine with blown flaps showed substantial differences for the various exhaust configurations tested. The differences in observed noise are related primarily to nozzle effective exhaust velocity, flap impingement velocity, and noise spectral shape.

Samanich, N. E.↗
NASA NTRS2022

Design Optimization of Energized Composite Using Simulation and Experimental Methods

As electric vehicles (EVs) are evolving, innovative technologies like “energized composite” that can store energy in the car's body helps extend its range per charge. The composite's unique ability to function as both structural body panel and charge storage medium stems from its unique pattern design between “electrochemical areas (EcA)” and “epoxy area (EpA)”. Herein, a design optimization study is presented to obtain a balanced ratio between EcA versus EpA to maximize the charge storage ability of the composite while maintaining a decent tensile and bending strength. Simulations using ANSYS software and experimental confirmation using universal testing machines and electrochemical analyzers are used to derive optimum ratios between EcA and EpA. Uniaxial tension test and 3-point bend test have been performed to optimize the tensile and bend strengths, whereas cyclic voltammetry, galvanic charge–discharge, and electrochemical impedance spectroscopy are used to determine the electrochemical performance of various design configurations by modulating the ratios of EcA versus EpA. Overall, the highest achieved energy storage per lamina is 2531 mWh m−2 for a maximum of 81.6% EcA with a tensile strength of 417.73 MPa and bending strength of 263.13 MPa. This study is highly beneficial for EVs and aerospace applications.

energy storage↗
DOE OSTI2020

FRaZ: A Generic High-Fidelity Fixed-Ratio Lossy Compression Framework for Scientific Floating-point Data

With ever-increasing volumes of scientific floating-point data being produced by high-performance computing applications, significantly reducing scientific floating-point data size is critical, and error-controlled lossy compressors have been developed for years. None of the existing scientific floating-point lossy data compressors, however, support effective fixed-ratio lossy compression. Yet fixed-ratio lossy compression for scientific floating-point data not only compresses to the requested ratio but also respects a user-specified error bound with higher fidelity. In this paper, we present FRaZ: a generic fixed-ratio lossy compression framework respecting user-specified error constraints. The contribution is twofold. (1) We develop an efficient iterative approach to accurately determine the appropriate error settings for different lossy compressors based on target compression ratios. (2) We perform a thorough performance and accuracy evaluation for our proposed fixed-ratio compression framework with multiple state-of-the-art error-controlled lossy compressors, using several real-world scientific floating-point datasets from different domains. Experiments show that FRaZ effectively identifies the optimum error setting in the entire error setting space of any given lossy compressor. While fixed-ratio lossy compression is slower than fixed-error compression, it provides an important new lossy compression technique for users of very large scientific floating-point datasets.

Underwood, Robert↗
NASA NTRS1988

Proceedings of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) Performance Evaluation Workshop

The focus of the workshop was the assessment of data quality by the AVIRIS project. Summaries of 16 of the presentations are published. The AVIRIS performance evaluation period began in June 87 with flight data collection in the eastern U.S., and continued in the west until Oct. 87, after which the instrument was returned for post flight calibration. At the beginning, the sensor met all of the spatial, spectral and radiometric performance requirements except in spectrometer D, where the signal to noise ratio was below the required value. By the end, sensor performance had deteriorated due to failure of 2 critical parts and to some design deficiences. The independent assessment by the NASA investigators confirmed the assessment by the AVIRIS project. Some scientific results were derived and are presented. These include the mapping of the spatial variation of atmospheric precipitable water, detection of shift in chlorophyll red, and mineral identification.

Vane, Gregg↗
NASA NTRS1978

A critical examination of expansion tunnel performance

An experimental study of the performance of the expansion tunnel for various test gases and range of quiescent acceleration section and nozzle pressure, nozzle geometric area ratio, and nozzle axial station has been performed. Flow diagnostics used to examine expansion tunnel flow characteristics were time histories and profiles of pitot pressure and axial component of flow velocity. The purpose of this study was to determine experimentally what limitations might restrict predicted operational flexibility and the advantages and disadvantages of this mode of operation as compared to the expansion tube. Results are presented which demonstrate the expansion tunnel offers several advantages over the expansion tube, but the severity of the disadvantages of the tunnel makes the expansion tube mode of operation the more desirable for performing hypersonic-hypervelocity aerothermodynamic studies of proposed entry configurations.

Miller, C. G.↗
DOE OSTI2022

Sensitivity Study of Mini-Batch Size on a Long Short-Term Memory Network for In-situ Sensing of Core-to-shell Ratio of Microencapsulated Phase Change Materials

Microencapsulated phase change materials are being studied for applications for thermal energy storage in concentrated solar fields. During fabrication, the thickness of the encapsulation cannot be readily measured for real-time control. Therefore, a machine learning network, specifically a Long Short-Term Memory network, is being developed to estimate the ratio of the shell radius to core radius based on a one second temperature history. The mini-batch size determines how often the algorithm weights are updated during network training, and shuffle indicates whether the training data is shuffled during training. A general factorial design is used to analyze the effects of varying mini-batch size and shuffle, along with the core-to-shell ratio, on the RMSE of the response from the Long Short-Term Memory network. It was found that the network performed better for smaller core to shell ratios (less than 0.6) and had the lowest RMSE when the minibatch size was 128. The minimum RMSE found was 0.00501.

Shannon, Rebecca↗
NASA NTRS1994

Test results for rotordynamic coefficients of anti-swirl self-injection seals

Test results are presented for rotordynamic coefficients and leakage for three annular seals which use anti-swirl self-injection concept to yield significant improvement in whirl frequency ratios as compared to smooth and damper seals. A new anti-swirl self-inection mechanism is achieved by deliberately machining self-injection holes inside the seal stator mechanism which is used to achieve effective reduction of the tangential flow which is considered as a prime cause of rotor instability in high performance turbomachinery. Test results show that the self-injection mechanism significantly improves whirl frequency ratios; however, the leakage performance degrades due to the introduction of the self-injection mechanism. Through a series of the test program, an optimum anti-swirl self-injection seal which uses a labyrinth stator surface with anti-axial flow injections is selected to obtain a significant improvement in the whirl frequency ratio as compared to a damper seal, while showing moderate leakage performance. Best whirl frequency ratio is achieved by an anti-swirl self-injection seal of 12 holes anti-swirl and 6 degree anti-leakage injection with a labyrinth surface configuration. When compared to a damper seal, the optimum configuration outperforms the whirl frequency ratio by a factor of 2.

Kim, C. H.↗
DOE OSTI2017

CO 2 Capture by Cold Membrane Operation with Actual Power Plant Flue Gas

The main objective of the project was to develop a post-combustion CO 2 capture process based on the hybrid cold temperature membrane operation. The CO 2 in the flue gas from coal fired power plant is pre-concentrated to >60% CO 2 in the first stage membrane operation followed by further liquefaction of permeate stream to achieve >99% CO 2 purity. The aim of the project was based on DOE program goal of 90% CO 2 capture with >95% CO 2 purity from Pulverized Coal (PC) fired power plants with $40/tonne of carbon capture cost by 2025. The project moves the technology from TRL 4 to TRL 5. The project involved optimization of Air Liquide commercial 12” PI-1 bundle to improve the bundle productivity by >30% compared to the previous baseline (DE-FE0004278) using computational fluid dynamics (CFD) modeling and bundle testing with synthetic flue gas at 0.1 MWe bench scale skid located at Delaware Research and Technology Center (DRTC). In parallel, the next generation polyimide based novel PI-2 membrane was developed with 10 times CO 2 permeance compared to the commercial PI-1 membrane. The novel PI-2 membrane was scaled from mini-permeator to 1” permeator and 1” bundle for testing. Bundle development was conducted with a Development Spin Unit (DSU) installed at MEDAL. Air Liquide’s cold membrane technology was demonstrated with real coal fired flue gas at the National Carbon Capture Center (NCCC) with a 0.3 MWe field-test unit (FTU). The FTU was designed to incorporate testing of two PI-1 commercial membrane bundles (12” or 6” diameter) in parallel or series. A slip stream was sent to the next generation PI-2 membrane for testing with real flue gas. The system exceeded performance targets with stable PI-1 membrane operation for over 500 hours of single bundle, steady state testing. The 12” PI-1 bundle exceeded the productivity target by achieving ~600 Nm3/hr, where the target was set at ~455 Nm3/hr at 90% capture rate. The cost of 90% CO 2 capture from a 550 MWe net coal power plant was estimated between 40 and $45/tonne. A 6” PI-1 bundle exhibited superior bundle performance compared to the 12” PI-1 bundle. However, the carbon capture cost was not lower with the 6” PI-1 bundle due to the higher bundle installed cost. A 1” PI-1 bundle was tested to compare bundles with different length / diameter ratios. This bundle exhibited the lowest performance due to the different fiber winding pattern and increased bundle non-ideality. Several long-term and parametric tests were conducted with 3,200 hours of total run-time at NCCC. Finally, the new PI-2 membrane fiber was tested at a small scale (1” modules) in real flue gas and exhibited up to 10 times the CO 2 permeance and slightly lower CO 2 /N 2 selectivity as the commercial PI-1 fiber. This corresponded to a projected 4 - 5 times increase in the productivity per bundle and a potential cost reduction of $3/tonne for CO2 capture, as compared with PI-1. An analytical campaign was conducted to trace different impurities such as NOx, mercury, Arsenic, Selenium in gas and liquid samples through the carbon capture system. An Environmental, Health and Safety (EH&S) analysis was completed to estimate emissions from a 550 MWe net power plant with carbon capture using cold membrane. A preliminary design and cost analysis was completed for 550 tpd (~25 MWe) plant to assess the capital investment and carbon capture cost for PI-1 and PI-2 membrane solutions from coal fired flue gas. A comparison was made with an amine based solution with significant cost advantage for the membrane at this scale. Additional preliminary design and cost analysis was completed between coal, natural gas and SMR flue gas for carbon capture at 550 tpd (~25 MWe) plant.

01 COAL, LIGNITE, AND PEAT↗
NASA NTRS2004

Experimental and Computational Study of Trapped Vortex Combustor Sector Rig With Tri-Pass Diffuser

The Trapped Vortex Combustor (TVC) potentially offers numerous operational advantages over current production gas turbine engine combustors. These include lower weight, lower pollutant emissions, effective flame stabilization, high combustion efficiency, excellent high altitude relight capability, and operation in the lean burn or RQL modes of combustion. The present work describes the operational principles of the TVC, and extends diffuser velocities toward choked flow and provides system performance data. Performance data include EINOx results for various fuel-air ratios and combustor residence times, combustion efficiency as a function of combustor residence time, and combustor lean blow-out (LBO) performance. Computational fluid dynamics (CFD) simulations using liquid spray droplet evaporation and combustion modeling are performed and related to flow structures observed in photographs of the combustor. The CFD results are used to understand the aerodynamics and combustion features under different fueling conditions. Performance data acquired to date are favorable compared to conventional gas turbine combustors. Further testing over a wider range of fuel-air ratios, fuel flow splits, and pressure ratios is in progress to explore the TVC performance. In addition, alternate configurations for the upstream pressure feed, including bi-pass diffusion schemes, as well as variations on the fuel injection patterns, are currently in test and evaluation phases.

Hendricks, R. C.↗
NASA NTRS1974

Single-stage experimental evaluation of tandem-airfoil rotor and stator blading for compressors. Part 7: Data and performance for stage E

An axial flow compressor stage, having tandem airfoil blading, was designed for zero rotor prewhirl, constant rotor work across the span, and axial discharge flow. The stage was designed to produce a pressure ratio of 1.265 at a rotor tip velocity of 757 ft/sec. The rotor has an inlet hub/tip ratio of 0.8. The design procedure accounted for the rotor inlet boundary layer and included the effects of axial velocity ratio and secondary flow on blade row performance. The objectives of this experimental program were (1) to obtain performance with uniform and distorted inlet flow for comparison with the performance of a stage consisting of single-airfoil blading designed for the same vector diagrams and (2) to evaluate the effectiveness of accounting for the inlet boundary layer, axial velocity ratio, and secondary flows in the stage design.

Cheatham, J. G.↗
NASA NTRS1989

Space Station Technology Summary

The completion of the Space Station Propulsion Advanced Technology Programs established an in-depth data base for the baseline gaseous oxygen/gaseous hydrogen thruster, the waste gas resistojet, and the associated system operations. These efforts included testing of a full end-to-end system at National Aeronautics and Space Administration (NASA)-Marshall Space Flight Center (MSFC) in which oxygen and hydrogen were generated from water by electrolysis at 6.89 MPa (1,000 psia), stored and fired through the prototype thruster. Recent end-to-end system tests which generate the oxygen/hydrogen propellants by electrolysis of water at 20.67 MPa (3,000 psia) were completed on the Integrated Propulsion Test Article (IPTA) at NASA-Johnson Space Center (JSC). Resistojet testing has included 10,000 hours of life testing, plume characterization, and electromagnetic interference (EMI) testing. Extensive 25-lbf thruster testing was performed defining operating performance characteristics across the required mixture ratio and thrust level ranges. Life testing has accumulated 27 hours of operation on the prototype thruster. A total of seven injectors and five thrust chambers were fabricated to the same basic design. Five injectors and three thrust chambers designed to incorporate improved life, performance, and producibility characteristics are ready for testing. Five resistojets were fabricated and tested, with modifications made to improve producibility. The lessons learned in the area of producibility for both the O2/H2 thrusters and for the resistojet have resolved critical fabrication issues. The test results indicate that all major technology issues for long life and reliability for space station application were resolved.

Iacabucci, R.↗
NASA NTRS1973

Single-stage experimental evaluation of tandem-airfoil rotor stator blading for compressors. Part 6: Data and performance for stage D

An axial flow compressor stage, having single-airfoil blading, was designed for zero rotor prewhirl, constant rotor work across the span, and axial discharge flow. The stage was designed to produce a pressure ratio of 1.265 at a rotor tip velocity of 757 ft/sec. The rotor had an inlet hub/tip ratio of 0.8. The design procedure accounted for the rotor inlet boundary layer and included the effects of axial velocity ratio and secondary flow on blade row performance. The objectives of this experimental program were: (1) to obtain performance with uniform and distorted inlet flow for comparison with the performance of a stage consisting of tandem-airfoil blading designed for the same vector diagrams; and (2) to evaluate the effectiveness of accounting for the inlet boundary layer, axial velocity ratio, and secondary flows in the stage design. With uniform inlet flow, the rotor achieved a maximum adiabatic efficiency of 90.1% at design equivalent rotor speed and a pressure ratio of 1.281. The stage maximum adiabatic efficiency at design equivalent rotor speed with uniform inlet flow was 86.1% at a pressure ratio of 1.266. Hub radial, tip radial, and circumferential distortion of the inlet flow caused reductions in surge pressure ratio of approximately 2, 10 and 5%, respectively, at design rotor speed.

Clemmons, D. R.↗
NASA NTRS1988

Vectoring Single Expansion Ramp Nozzle (VSERN) static model test program

A variable throat-area, side-vectoring single expansion ramp nozzle (VSERN) concept's internal performance characteristics are studied with a view to controlling the bypass flow of an unmixed turbofan engine. Static tests have been conducted on VSERN at NASA-Langley using a variety of parametric models giving attention to the effects of upstream bend angle, ramp geometry, area ratio, and nozzle pressure ratio on static thrust and flow performance. Advantages of VSERN over the conventional vectoring axisymmetric convergent side-nozzles typified by those of the Harrier's Pegasus engine.

Eames, D. J. H.↗
DOE OSTI2017

Collisionality dependence and ion species effects on heat transport in He and H plasma, and the role of ion scale turbulence in LHD

Here, surveys of the ion and electron heat transports of neutral beam (NB) heating plasma were carried out by power balance analysis in He and H rich plasma at LHD. Collisionality was scanned by changing density and heating power. The characteristics of the transport vary depending on collisionality. In low collisionality, with low density and high heating power, an ion internal transport barrier (ITB) was formed. The ion heat conductivity (χ i ) is lower than electron heat conductivity (χ e ) in the core region at ρ < 0.7. On the other hand, in high collisionality, with high density and low heating power, χ i is higher than χ e across the entire range of plasma. These different confinement regimes are associated with different fluctuation characteristics. In ion ITB, fluctuation has a peak at ρ = 0.7, and in normal confinement, fluctuation has a peak at ρ = 1.0. The two confinement modes change gradually depending on the collisionality. Scans of concentration ratio between He and H were also performed. The ion confinement improvements were investigated using gyro-Bohm normalization, taking account of the effective mass and charge. The concentration ratio affected the normalized χ i only in the edge region (ρ ~ 1.0). This indicates ion species effects vary depending on collisionality. Turbulence was modulated by the fast ion loss instability. The modulation of turbulence is higher in H rich than in He rich plasma.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
NASA NTRS1978

Effects of data asymmetry on Shuttle Ku-band communications link performance

This paper systematically analyzes the signal-to-noise ratio degradations which can potentially occur due to data asymmetry in digital transmission systems. Suitable asymmetry models are developed and error probability performance for various types of data detectors (integrate-and-dump filter, filter-sample detector, and gated-integrate-and-dump filter) is derived. Although this work was done to resolve problems being encountered in the Shuttle Ku-band return link design, specifically for the 50 Mbit/s convolutionally encoded channel (NRZ format), generalizations are made which provide results for other cases of interest (other Ku-band return link channels, or other systems entirely). This paper therefore considers Manchester data formats (in addition to NRZ) and uncoded transmission (in addition to convolutionally coded transmission). The effects of bandlimiting are also considered.

Simon, M. K.↗