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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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

10-kHz PLIF Thermometry for a Turbulent Jet Flame using Single Burst-mode OPO

Two-color Planar laser-induced fluorescence (TC-PLIF) thermometry techniques that employ two laser systems and two cameras face challenges when implemented in practical combustion facilities because of experimental complexity and multiple laser and camera requirements, particularly for high-speed TC-PLIF. To circumvent those problems, we developed a fast, dual-wavelength switching, burst-mode OPO technology to significantly reduce the experimental complexity of high-speed TC-PLIF thermometry and simplify its implementation in harsh combustion and flow test facilities. A fast, dual-wavelength switched seed laser enabled a high-energy, high-repetition-rate burst-mode laser to generate two 10-kHz pulse trains at wavelengths of ~354.8 nm. The injection-seeded OPO efficiently converts the burst-mode laser output to285.62 nm and 285.67 nm to excite the Q2(12) and P1(8) OH transitions. PLIF images were collected from each of the two excitation transitions with a single camera and an UV intensifier, and intensity ratios from the images were used to determine local temperatures. Ten kHz hydroxyl radical (OH) TC-PLIF for premixedCH4/Air/H2 jet flame was demonstrated.

thermometry↗
NASA NTRSDate not supplied

10-kHz PLIF Thermometry for Turbulent Jet Flame using Single Burst-mode OPO

Two-color Planar Laser-Induced Fluorescence (TC-PLIF) thermometry techniques that employ two laser systems and two cameras face challenges when implemented in practical combustion facilities because of experimental complexity and multiple laser and camera requirements, particularly for high-speed TC-PLIF. To circumvent those problems, we developed a fast, dual-wavelength switching, burst-mode OPO technology to significantly reduce the experimental complexity of high-speed TC-PLIF thermometry and simplify its implementation in harsh combustion and flow test facilities. A fast, dual-wavelength switched seed laser enabled a high-energy, high-repetition-rate burst-mode laser to generate two 10-kHz pulse trains at wavelengths of ~354.8 nm. The injection-seeded OPO efficiently converts the burst-mode laser output to 285.62 nm and 285.67 nm to excite the Q2(12) andP1(8) OH transitions. PLIF images were collected from each of the two excitation transitions with a single camera and an UV intensifier, and intensity ratios from the images were used to determine local temperatures. Ten kHz hydroxyl radical (OH) TC-PLIF for premixedCH4/Air/H2 jet flame was demonstrated.

thermometry↗
NASA NTRS2021

Evolution of Tropical Cyclone Properties Across the Development Cycle of the GISS-E3 Global Climate Model

The next-generation global climate model from the NASA Goddard Institute for Space Studies, GISS-E3, contains many improvements to resolution and physics that allow for improved representation of tropical cyclones (TCs) in the model. This study examines the properties of TCs in two different versions of E3 at different points in its development cycle, run for 20 years at 0.5 degree resolution, and compares these TCs with observations, the previous generation GISS model, E2, and other climate models. E3 shares many TC biases common to global climate models, such as having too few tropical cyclones, but is much improved from E2. E3 produces strong enough TCs that observation-based wind speed thresholds can now be used to detect and track them, and some storms now reach hurricane intensity; neither of these was true of E2. Model development between the first and second versions of E3 further increased the number and intensity of TCs and reduced TC count biases globally and in most regions. One-year sensitivity tests to changes in various microphysical and dynamical tuning parameters are also examined. Increasing the entrainment rate for the more strongly-entraining plume in the convection scheme increases the number of TCs (though also affecting other climate variables, and in some cases increasing biases). Variations in divergence damping did not have a strong effect on simulated TC properties, contrary to expectations based on previous studies. Overall, the improvements in E3 make it more credible for studies of TC activity and its relationship to climate.

Tropical Cyclones↗
NASA NTRS2024

Convective Characteristics and GOES GLM Optical Energy in Hurricane Ian (2022)

Tropical cyclone (TC) track forecasts have improved greatly in recent decades, while intensity forecasts have struggled to improve at the same rate. As a result, there has been a focus in literature to attempt to better understand the processes that lead to TC intensification and especially TC rapid intensification (RI). Lightning has been studied as a tool to determine changes in TC intensity, but studied thus far have had conflicting results.

Hurricane↗
NASA NTRSDate not supplied

Relating Lightning Flash Characteristics to Convective Structure in Tropical Cyclones

For decades, lightning has been used with some success as an indicator of tropical cyclone (TC) intensity change. An increase in inner-core lightning is usually associated with TC intensification, but this is not always the case. Significant lightning outbreaks have been observed in weakening storms, and hurricanes can rapidly intensify in the total absence of inner-core lightning. These conflicting results arise because lightning production depends on convective and microphysical characteristics that can arise during both intensification and weakening phases in TCs. Recent work using flash size and energy metrics provided by the Geostationary Lightning Mapper (GLM) aboard the GOES-R series of satellites shows some promise in distinguishing between lightning outbreaks that correspond to intensification and those that correspond to weakening. If a hurricane is rapidly intensifying in the presence of inner-core lightning, the size and optical energy of the flashes generally increases as intensification proceeds. It is hypothesized that this relationship is governed by changes in the TC-scale circulation that produce enhanced upper-level outflow and large, strongly helical convective updrafts in the inner core. These changes increase the quantity and spatial extent of charged upper-level ice, which allows large intracloud flashes to occur when electric field breakdown occurs. This presentation will present objective diagnostics of convective asymmetry using azimuthal wavenumber decomposition of GOES-R Advanced Baseline Imager brightness temperatures. The degree of symmetry will be related to GLM flash characteristics to better understand how changes in the symmetry of TC inner-core convection relates to flash rate, size, and energy. It will also show how the evolution of inner-core asymmetries relates to the spatial distribution and characteristics of lightning flashes in the inner core.

Patrick Duran↗
NASA NTRSDate not supplied

NASA’s Efficient Quiet Integrated Propulsors (Equip) Technical Challenge

Advances in aircraft propulsor technology - ducted and unducted - are key elements to developing a sustainable aviation future. Increasing propulsive efficiency comes with significant challenges. The long-term trend in aircraft engine design has been towards higher bypass ratios to increase efficiency and decrease noise. Current designs are pushing against limits on engine size; the engine must fit under the wing and overcome the nacelle weight, aerodynamic drag, and airframe integration penalties associated with an ultra-high bypass ratio. The next-generation ducted engines will have shorter inlets and smaller rotor-stator spacing to minimize nacelle area. This increases the potential for non-uniform flow at the fan face and less area for acoustic liners. Unducted engines eliminate the nacelle penalty while presenting challenges to noise and operability in distorted flow environments. The overall diameter in both cases raises questions about engine-airframe integration to maximize efficiency gains and minimize installation penalties. The National Aeronautics and Space Administration (NASA) Advanced Air Vehicles Program (AAVP) approved the Efficient Quiet Integrated Propulsor (EQuIP) Technical Challenge (TC) under the Advanced Air Transport Technology (AATT) Project to work on next-generation propulsor technologies in collaboration with NASA’s government and industry partners in the Sustainable Flight National Partnership. The EQuIP TC leverages NASA resources with Federal Aviation Administration (FAA) and industry investments under the FAA’s Continuous Lower Energy Emissions and Noise (CLEEN) program to address technical challenges on the propulsor subject to the flow field imposed by the engine-airframe-flight environment. The EQuIP TC complements NASA Aeronautics Research Mission Directorate’s (ARMD) existing investments in sustainable aviation for the next-generation of commercial aircraft and contributes to meeting the noise and efficiency goals set by the Sustainable Flight National Partnership and U.S. Aviation Climate Action Plan. This paper introduces the EQuIP TC, describes key parts of its development, and presents the background research used to scope its impact.

Propulsion↗
NASA NTRSDate not supplied

Observation of Deep Convective Cloud-Top Height and Vertical Temperature Structure of Hurricane Using Hyperspectral Infrared Sounder and its Single-Field-View Retrieval Products

A new method utilizing hyperspectral infrared sounders is developed to estimate cloud top height (CTH) for deep convective clouds from hurricane, or tropical cyclone (TC). By analyzing measurements from the Cross-track Infrared Sounder (CrIS), and further validating with radiative transfer simulations, we identified an inverted-V spectral feature in the ozone (O3) band near 9.6 μm, which correlates with deep convective clouds. The depth of this feature can be used to estimate the CTH of a TC's eyewall and surrounding rain bands. This approach effectively captures the cloud structure of the TC. Additionally, a new single Field of View sounder products (SiFSAP), derived from CrIS and the Advanced Technology Microwave Sounder (ATMS), will be used to analyze the vertical temperature and water vapor structure, offering more insights into TC dynamics.

Single-field-view retrieval↗
NASA NTRSDate not supplied

Results of the NASA Prediction Uncertainty Reduction Tech Challenge

In January 2021 the Advanced Air Vehicles Program approved a new Tech Challenge (TC) to be run out of the Commercial Supersonic Technology (CST) Project. The objective of the TC was to bring uncertainties in the empirical noise modeling for civilian supersonic aircraft into the same range as that of conventional aircraft. The TC goal statement was to “Produce data and demonstrate tools that reduce the uncertainty in predicting Landing & Takeoff Noise levels of supersonic-relevant designs by 5 EPNdB and are ready for use in studies to inform FAA rule-making.” To make the required improvements in noise prediction methods for supersonic aircraft, NASA decided to validate and use high-fidelity numerical simulations to acquire the needed noise data on supersonic propulsion configurations. High-fidelity component designs were developed, such as a two-stage propulsor behind a supersonic inlet designed by General Electric Aviation and variable area exhaust systems using input from recent contracts with GE and Rolls Royce. A noise database was generated as a function of geometric and flow parameters, providing corrections to the empirical noise models and added new input variables to describe the complexities created by the supersonic-specific design features. Statistically, the new models were able to predict the acoustic impact of supersonic-specific features, the reduction in uncertainty being reduced from the baseline 7.8 EPNdB at the beginning of the TC to 2.0 EPNdB at the end.

noise prediction↗
DOE OSTI2023

Open Source High Fidelity Modeling of a Type-5 Wind Turbine Drivetrain

The increasing integration of renewable energy resources in evolving bulk power system (BPS) is impacting the system inertia. Type-5 wind turbine generation has the potential to behave like a traditional synchronous generator and can help mitigate the impact on system inertia. A hydraulic torque converter (TC) and gearbox with torque limiting feature are integral parts of a Type-5 wind turbine unit. A high fidelity model of Type-5 wind turbine drivetrain is not openly and widely available for grid integration and transient stability studies. This hinders appropriate assessment of Type-5 wind power plant’s contribution to bulk grid resilience. This work develops and validates a TC model based on those generally used in automobile’s transmission system. Moreover, the concept of torsional coupling is leveraged to integrate the TC and gearbox system dynamics. The entire integrated model will be open sourced and publicly available for grid integration studies.

17 WIND ENERGY↗
DOE OSTI2021

INGENIOUS Thermal Conductivity Measurement Source Categorization

Thermal conductivity (TC) data taken for different wells at a specified drill depth. This is an abridged version of the complete SMU heat flow database, downloaded from the SMU node of the NGDS at the beginning of INGENIOUS (approximately April 2021), and filtered to the INGENIOUS study area. This National Geothermal Data System (NGDS) project aggregates geothermal data collected and curated by the SMU Geothermal Laboratory and its partner organizations. All columns in this database are the same as the SMU database, except for 2 additions associated with this project. Repeated columns are for data correlation purposes. Column descriptions and data types are the same as previous iterations of the SMU database. The new values that are the addition are two new columns developed as part of the INGENIOUS project: INGENIOUS TC Value | INGENIOUS notes INGENIOUS notes are individual notes that were written for specific data points during the analysis process. There are not always notes associated with each input value. INGENIOUS TC Value includes 4 values: 1. Assumed Measured These are values that are assumed to be measured thermal conductivity values, either within a specific well or within the same study region. Many of these have either a published reference, a reported standard deviation, or a unique thermal conductivity value. 2. Data release - assumed measured These are values in the SMU database that are from proprietary data that were added to the SMU database and are labeled as data release for their reference. These values were searched for in person at the SMU Geothermal Laboratory as well as virtual examination of data available on the NGDS. For many of these, there are reported thermal conductivity values associated with the heat flow data in the database, but no specific table or reference to measurements in the original data release files. 3. Known measured These are values that have a reported measurement, either as an original file in the SMU data files on the NGDS or a reported table in a publication. In the rare circumstances, Maria Richards or David Blackwell confirmed measurement. Confirmation of measurement would be written in the INGENIOUS notes column. 4. Unmeasured Unmeasured values are those that are known to be unmeasured, either estimated from another report or no information given. In the SMU database, there are wells that have a heat flow but no thermal conductivity. These are categorized as unmeasured. There are also heat flow values that are stated to have estimated or generalized average thermal conductivity values for the region and rock type. Because these are known to be unmeasured, they are categorized as such. 5. Blank Blank values are either A quality or X quality. These quality values are stated in the INGENIOUS notes. These values were not going to change associated with the heat flow analysis, so these were not examined.

15 GEOTHERMAL ENERGY↗
DOE OSTI2020

Materials Data on HfTc by Materials Project

HfTc is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Hf is bonded in a body-centered cubic geometry to eight equivalent Tc atoms. All Hf–Tc bond lengths are 2.83 Å. Tc is bonded in a body-centered cubic geometry to eight equivalent Hf atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al12Tc by Materials Project

TcAl12 crystallizes in the cubic Im-3 space group. The structure is three-dimensional. Tc is bonded in a cuboctahedral geometry to twelve equivalent Al atoms. All Tc–Al bond lengths are 2.72 Å. Al is bonded in a 1-coordinate geometry to one Tc and ten equivalent Al atoms. There are a spread of Al–Al bond distances ranging from 2.76–2.89 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pu2Si4Tc3 by Materials Project

Pu2Tc3Si4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Pu+4.50+ is bonded in a 1-coordinate geometry to four Tc3- atoms. There are a spread of Pu–Tc bond distances ranging from 2.84–3.20 Å. There are two inequivalent Tc3- sites. In the first Tc3- site, Tc3- is bonded in a 12-coordinate geometry to four equivalent Pu+4.50+ and six Si atoms. There are a spread of Tc–Si bond distances ranging from 2.50–2.52 Å. In the second Tc3- site, Tc3- is bonded in a 7-coordinate geometry to two equivalent Pu+4.50+ and five Si atoms. There are a spread of Tc–Si bond distances ranging from 2.42–2.50 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded in a 6-coordinate geometry to four Tc3- atoms. In the second Si site, Si is bonded in a 4-coordinate geometry to four Tc3- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti2ReTc by Materials Project

Ti2ReTc is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Ti is bonded in a body-centered cubic geometry to four equivalent Re and four equivalent Tc atoms. All Ti–Re bond lengths are 2.70 Å. All Ti–Tc bond lengths are 2.70 Å. Re is bonded in a body-centered cubic geometry to eight equivalent Ti atoms. Tc is bonded in a body-centered cubic geometry to eight equivalent Ti atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsTcNClO4 by Materials Project

CsTcNO4Cl crystallizes in the orthorhombic P2_12_12_1 space group. The structure is three-dimensional. Cs1+ is bonded in a 9-coordinate geometry to six O2- and three equivalent Cl1- atoms. There are a spread of Cs–O bond distances ranging from 3.21–3.64 Å. There are a spread of Cs–Cl bond distances ranging from 3.57–3.65 Å. Tc3+ is bonded in a 6-coordinate geometry to one N5+, four O2-, and one Cl1- atom. The Tc–N bond length is 1.65 Å. There is three shorter (1.97 Å) and one longer (1.98 Å) Tc–O bond length. The Tc–Cl bond length is 2.38 Å. N5+ is bonded in a single-bond geometry to one Tc3+ atom. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Cs1+, one Tc3+, and one O2- atom. The O–O bond length is 1.45 Å. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one Tc3+ and one O2- atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Cs1+, one Tc3+, and one O2- atom. The O–O bond length is 1.44 Å. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Cs1+, one Tc3+, and one O2- atom. Cl1- is bonded in a distorted single-bond geometry to three equivalent Cs1+ and one Tc3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TlTcIr2 by Materials Project

TcIr2Tl is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Tc is bonded in a distorted body-centered cubic geometry to eight equivalent Ir atoms. All Tc–Ir bond lengths are 2.80 Å. Ir is bonded in a body-centered cubic geometry to four equivalent Tc and four equivalent Tl atoms. All Ir–Tl bond lengths are 2.80 Å. Tl is bonded in a body-centered cubic geometry to eight equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2FeTc by Materials Project

Hf2TcFe is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Hf is bonded in a body-centered cubic geometry to four equivalent Tc and four equivalent Fe atoms. All Hf–Tc bond lengths are 2.78 Å. All Hf–Fe bond lengths are 2.78 Å. Tc is bonded in a body-centered cubic geometry to eight equivalent Hf atoms. Fe is bonded in a body-centered cubic geometry to eight equivalent Hf atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TcPbO3 by Materials Project

TcPbO3 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are three inequivalent Tc4+ sites. In the first Tc4+ site, Tc4+ is bonded to six O2- atoms to form corner-sharing TcO6 octahedra. The corner-sharing octahedral tilt angles are 43°. There is two shorter (1.98 Å) and four longer (1.99 Å) Tc–O bond length. In the second Tc4+ site, Tc4+ is bonded to six O2- atoms to form corner-sharing TcO6 octahedra. The corner-sharing octahedral tilt angles are 43°. There is two shorter (1.98 Å) and four longer (1.99 Å) Tc–O bond length. In the third Tc4+ site, Tc4+ is bonded to six O2- atoms to form corner-sharing TcO6 octahedra. The corner-sharing octahedral tilt angles are 43°. All Tc–O bond lengths are 1.99 Å. There are three inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded in a hexagonal planar geometry to six O2- atoms. There are four shorter (2.64 Å) and two longer (2.65 Å) Pb–O bond lengths. In the second Pb2+ site, Pb2+ is bonded in a hexagonal planar geometry to six O2- atoms. There are four shorter (2.64 Å) and two longer (2.65 Å) Pb–O bond lengths. In the third Pb2+ site, Pb2+ is bonded in a hexagonal planar geometry to six O2- atoms. There are two shorter (2.64 Å) and four longer (2.65 Å) Pb–O bond lengths. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two Tc4+ and two Pb2+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two Tc4+ and two Pb2+ atoms. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two Tc4+ and two Pb2+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Tc4+ and two Pb2+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two Tc4+ and two Pb2+ atoms. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to two Tc4+ and two equivalent Pb2+ atoms.

36 MATERIALS SCIENCE↗