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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Numerical Simulation of a Simplified High-Lift CRM Configuration Embedded with Fluidic Actuators

Numerical simulations have been performed for a simplified high-lift configuration that is representative of a modern transport airplane. This configuration includes a leading-edge slat, fuselage, wing, nacelle-pylon and a simple hinged flap. The suction surface of the flap is embedded with multiple rows of fluidic actuators to reduce the extent of reversed flow regions and improve the aerodynamic performance of the configuration with flap in a deployed state. In the current paper, a Lattice Boltzmann Method based high-fidelity computational fluid dynamics (CFD) code, known as PowerFLOW® is used to simulate the entire flow field associated with this configuration, including the flow inside the actuators. A fully compressible version of the PowerFLOW® code that has been validated for high speed flows is used for the present simulations to accurately represent the transonic flow regimes that are encountered in the flow field generated by the actuators operating at higher mass flow (momentum) rates required to mitigate reverse flow regions on the suction surfaces of the main wing and the flap. The numerical solutions predict the expected trends in aerodynamic forces as the actuation levels are increased. More efficient active flow control (AFC) systems and actuator arrangement for lift augmentation are emerging based on the parametric studies conducted here prior to wind tunnel tests. These numerical solutions will be compared with experimental data, once such data becomes available.

Vatsa, Veer N.↗
NASA NTRS2019

Agile Approach to Assuring the Safety-Critical Embedded Software for NASA's Orion Spacecraft

Human-rated missions like those in NASA's Orion Program continue to grow in complexity. The role of software in achieving ambitious mission objectives has expanded dramatically in the last few decades. Assuring the safety and performance of the embedded flight software is quickly growing beyond the reach of traditional methods and resource levels. The methods used to build these software-dominant systems evolve in an on-going attempt to keep pace with the scope of our ambitions. Agile software development is now commonplace. The long timelines and large batches of work associated with traditional methods are being replaced by rapid delivery of small increments _ as system capabilities are realized in waves. Assurance of these critical software capabilities must therefore conquer an ever-expanding frontier of challenges, and do so with an approach matched to the evolving development methods. This paper recounts the journey of the Orion Independent Verification and Validation (IV&V) team as we addressed this dynamic environment. Widening our aperture to encompass a dramatically larger mission scope, while adjusting our cadence to synchronize with the rapid pace of agile software development, a new approach to IV&V is emerging. This approach is characterized by a sharper focus on mission capabilities, matched with a method to dynamically _follow the risk' as the IV&V team delivers more compelling assurance data in waves. Traditional methods prevalent in IV&V tend to scope the work using artifacts of the development process as they evolve from preliminary to final versions, and the pace of delivery was synchronized with the development timelines prevalent in the waterfall lifecycle. That more static approach is out of phase with the demands of the new environment. Scoping work according to the critical capabilities of the system (rather than artifacts of development) and synchronizing with the rapid pace of agile development, we are moving toward more effective parity with the demands of the environment. We explain the concrete steps we took, the principles that motivated our choices, and the results we have achieved to date.

Capability based assurance↗
NASA NTRS2018

The Effects of Fiber Orientation and Adhesives on Tensile Properties of Carbon Fiber Reinforced Polymer Matrix Composite with Embedded Nickel-Titanium Shape Memory Alloys

Tensile tests of Nickel-titanium (NiTi) shape memory alloys (SMA) embedded within carbon fiber reinforced polymer matrix composite (CFRP/PMC) laminates were evaluated with simultaneous monitoring of modal acoustic emissions (MAE). Three different layup configurations utilizing two different thin film adhesives were applied to bond the materials. Ultimate tensile strengths, strains, and moduli were obtained along with cumulative AE energy of events and specimen failure location. Scanning electron microscopy was used to examine the break areas of the specimens post-test. Microscopy was used to validate failure locations revealed from MAE analysis. A unique finding within this research showed that 90° plies in the outer ply gave the strongest acoustic signals as well as the cleanest fracture of the specimens tested. Overlapping 0° ply layers surrounding the SMA was found to be the best scenario to prevent failure of the specimen itself.

Derek Quade↗
NASA NTRSDate not supplied

Enhancing Fault Isolation for Health Monitoring of Electric Aircraft Propulsion by Embedding Failure Mode and Effect Analysis into Bayesian Networks

This paper describes a fault isolation approach for electric powertrains of unmanned aerial vehicles. The approach leverages the combination of failure mode and effect analysis (FMEA) and Bayesian networks, thus introducing depend-ability structures into a diagnostic framework. Faults and failure events from the FMEA are mapped within a Bayesian network, where network edges replicate the links embedded within FMEAs. This framework helps the fault isolation process by identifying the probability of occurrence of specific faults or root causes given evidence observed through sensor signals. The framework is applied to an electric power-train system of a small, rotary-wing unmanned aerial vehicle, demonstrating how a Bayesian network enhanced by FMEA helps disambiguate between root causes of incipient failures, which would otherwise be considered as equally probable.

Fault Isolation↗
NASA NTRS1993

Toward an Embedded Training Tool for Deep Space Network Operations

There are three issues to consider when building an embedded training system for a task domain involving the operation of complex equipment: (1) how skill is acquired in the task domain; (2) how the training system should be designed to assist in the acquisition of the skill, and more specifically, how an intelligent tutor could aid in learning; and (3) whether it is feasible to incorporate the resulting training system into the operational environment. This paper describes how these issues have been addressed in a prototype training system that was developed for operations in NASA's Deep Space Network (DSN). The first two issues were addressed by building an executable cognitive model of problem solving and skill acquisition of the task domain and then using the model to design an intelligent tutor.

Johnson, W. Lewis↗
NASA NTRS2019

UAVSAR real-time embedded GPU processor

Synthetic aperture radar (SAR) can provide high-resolution imagery regardless of cloud cover or lighting conditions. These qualities make SAR potentially well-suited for informing response efforts to natural and man-made disasters, but such applications require data products with minimal latency. To meet this challenge, we implemented a real-time SAR processor capable of producing 10 m imagery using an NVIDIA Jetson TX2 embedded GPU module. With its low mass (87 g module) and power consumption under 8 W, the system also holds promise for spaceborne applications.

Tung, Wayne↗
NASA NTRS2021

Chandra Grating Spectroscopy of Embedded Wind Shock X-ray Emission from O Stars Shows Low Plasma Temperatures and Significant Wind Absorption

We present a uniform analysis of six examples of embedded wind shock (EWS) O star X-ray sources observed at high resolution with the Chandra grating spectrometers. By modeling both the hot plasma emission and the continuum absorption of the soft X-rays by the cool, partially ionized bulk of the wind we derive the temperature distribution of the shock-heated plasma and the wind mass-loss rate of each star. We find a similar temperature distribution for each star’s hot wind plasma, consistent with a power-law differential emission measure, dlogEMdlogT, with a slope a little steeper than -2, up to temperatures of only about107K. The wind mass-loss rates, which are derived from the broadband X-ray absorption signatures in the spectra, are consistent with those found from other diagnostics. The most notable conclusion of this study is that wind absorption is a very important effect, especially at longer wavelengths. More than 90 per cent of the X-rays between 18 and 25 ̊A produced by shocks in the wind of ζPup are absorbed, for example. It appears that the empirical trend of X-ray hardness with spectral subtype among O stars is primarily an absorption effect.

David H Cohen↗
NASA NTRS2020

An embedded planar-foil capacitor material, FPGA based interposer, aimed at improving system performance and reduced board size for space based electronics

This paper presents work to date in developing, and testing an embedded planar-foil capacitor based interposer intended to be integrated together with high-density components such as Field Programmable Gate Arrays (FPGAs), and Application Specific Integrated Circuits (ASIC). FPGA devices typically have a large number of I/O and power pins. The high speed enabled by these devices requires a large number of discrete bypass capacitors as close as possible to the power pins. These capacitors take up a considerable amount of the board area on the application circuit board. The developed interposer replaces these components freeing up space of traditional bypass capacitors for other circuitry.

Cheng, Ben↗
NASA NTRS2022

Radiation-induced D/H Exchange Rate Constants in Aliphatics Embedded in Water Ice

Gas-phase and solid-state chemistry in low-temperature interstellar clouds and cores leads to a D/H enhancement in interstellar ices, which is eventually inherited by comets, meteorites, and even planetary satellites. Hence, the D/H ratio has been widely used as a tracer for the origins of extraterrestrial chemistry. However, the D/H ratio can also be influenced by cosmic rays, which are ubiquitous and can penetrate even dense interstellar molecular cores. The effects of such high-energy radiation on deuterium fractionation have not been studied in a quantitative manner. In this study, we present rate constants for radiation-induced D-to-H exchange for fully deuterated small (1–2 C) hydrocarbons embedded in H2O ice at 20 K and H-to-D exchange for the protiated forms of these molecules in D2O ice at 20 K. We observed larger rate constants for H-to-D exchange in the D2O ice versus D-to-H exchange in H2O ice, which we have attributed to the greater bond strength of C–D versus C–H. We find that the H-to-D exchange rate constants are smaller for protiated methane than ethane, in agreement with bond energies from the literature. We are unable to obtain rate constants for the unsaturated and reactive hydrocarbons ethylene and acetylene. Interpretation of the rate constants suggest that D/H exchange products are formed in abundance alongside radiolysis products. We discuss how our quantitative and qualitative data can be used to interpret the D/H ratios of aliphatic compounds observed throughout space.

Ice destruction↗
NASA NTRSDate not supplied

Hypersonic Fluid-Thermal-Structural Interactions on a Compression Ramp with an Embedded Compliant Panel

The fluid-thermal-structural interactions of a compliant panel embedded in a compression ramp are explored experimentally at Mach 6. The panel structural response is investigated for turbulent and transitional shock-wave/boundary-layer interactions at five distinct interaction strengths and up to four different pressure differentials. Upstream of the compression corner, fast-response piezoresistive pressure transducers show the feedback of the panel vibrations and static deflection on the upstream pressure fluctuations. The magnitude of the pressure fluctuation rms shows a reduction in the upstream disturbances when a pressure differential is applied across the compliant panel. Photogrammetry and IR thermography are used simultaneously to measure the panel deformations and surface temperature. Panel deformation, frequency shifting, and frequency bifurcation are consistent with post-thermal-buckling behavior.

hypersonic↗
NASA NTRSDate not supplied

Extending Acoustic Liner Bandwidth with Simple Embedded Septa

An acoustic liner design incorporating single-hole perforate septa was evaluated by the NASA Langley Liner Physics Team. The design, termed the ‘Simplified Septa’ concept, incorporates embedded septa as found in traditional, multidegree-of-freedom liners. Generally, such septa are composed of multihole perforates or porous mesh, whereas this concept uses septa with one hole per cell. An optimization scheme was employed to determine septa placement and hole diameters based on a target impedance cost function. Versions of the concept are tested in the NASA Langley Normal Incidence Tube (NIT) to determine impedance and absorption spectra for swept tonal excitation at 120 and 140 dB. Experimental results are compared to predictions from a liner model based on the Zwikker-Kosten Transmission Line (ZKTL) code and show good agreement for no-flow conditions.

acoustics↗
NASA NTRSDate not supplied

Extending Acoustic Liner Bandwidth with Simple Embedded Septa

An acoustic liner design incorporating single-hole perforate septa was evaluated by the NASA Langley Liner Physics Team. The design, termed the ‘Simplified Septa’ concept, incorporates embedded septa as found in traditional, multidegree-of-freedom liners. Generally, such septa are composed of multihole perforates or porous mesh, whereas this concept uses septa with one hole per cell. An optimization scheme was employed to determine septa placement and hole diameters based on a target impedance cost function. Versions of the concept are tested in the NASA Langley Normal Incidence Tube (NIT) to determine impedance and absorption spectra for swept tonal excitation at 120 and 140 dB. Experimental results are compared to predictions from a liner model based on the Zwikker-Kosten Transmission Line (ZKTL) code and show good agreement for no-flow conditions.

acoustics↗
NASA NTRS2024

Multiple Subscale Magnetic Reconnection Embedded inside a Heliospheric Current Sheet Reconnection Exhaust: Evidence for Flux Rope Merging

We report observations of multiple subscale reconnecting current sheets embedded inside a large-scale heliospheric current sheet (HCS) reconnection exhaust. The discovery was made possible by the unusual skimming trajectory of Parker Solar Probe through a sunward-directed HCS exhaust, sampling structures convecting with the exhaust outflows for more than 3 hr during Encounter 14, at a radial distance of ∼17 solar radii. A large number of subscale current sheets (SCSs) were detected inside the HCS exhaust. Remarkably, five SCSs showed direct evidence for reconnection, displaying near-Alfvénic outflow jets and bifurcated current sheets. The reconnecting SCSs all had small magnetic shears (27°–81°), i.e., strong guide fields. The thickness of the subscale reconnecting current sheets ranged from ∼60 km to ∼5000 km (∼20–2000 ion inertial lengths). The SCS exhausts were directed predominantly in the normal or out-of-plane direction of the HCS, i.e., nearly orthogonal to the HCS exhaust direction. The presence of multiple low-magnetic-shear reconnecting current sheets inside a large-scale exhaust could be associated with coalescence of multiple large flux ropes inside the HCS exhaust. The orientation of some SCS exhausts was partly in the ecliptic plane of the HCS, which may indicate that the coalescence process is highly three-dimensional. Since the coalescence process is likely short-lived, the detection of five such events inside a single HCS crossing could imply the common occurrence of flux rope coalescence in large-scale HCS reconnection exhausts.

T D Phan↗
DOE OSTI2024

Development & Experimental Validation of a Generalized Resistance-Capacitance Model for Numerical Simulation of Phase-Change Material Embedded Heat Exchangers

Latent heat thermal energy storage (LHTES) using phase change material (PCM) has attracted increased attention as a viable solution for overcoming the mismatch between energy supply and demand for renewable energy-based systems. PCM-embedded heat exchangers (PCM-HX) have the potential to significantly improve thermal performance due to high storage capacity and low temperature variation during the phase change process. Most models for simulating LHTES heat transfer use Computational Fluid Dynamics (CFD) simulations, which have high computational costs resulting from considering the complex and time-dependent physics relevant to PCM-HXs. In this paper, a Generalized Resistance Capacitance-based Model (GRCM) was developed to predict the thermal performance of arbitrary PCM-HXs in a computationally efficient manner without compromising modeling accuracy. The GRCM is exercised for three case studies: (i) verification for a single-slabbed finned PCM-HX, (ii) verification and validation for a copper foam/paraffin composite PCM-HX, and (iii) validation for a straight tube annular finned PCM-HX. The copper foam PCM-HX uses an electric heater at the top of HX, while the other two configurations utilize water as heat transfer fluid. For the single-slabbed finned PCM-HX melting case, the mean deviation in average PCM temperature predicted by the GRCM compared to the CFD model was between 0.56 – 0.73 K, with maximum temperature deviation of 2.68 K. For the HTF outlet temperature, the validation results showed that GRCM prediction matches very well with experimental data, with mean temperature deviation of 0.24 K during melting case, while for solidification case was 0.34 K. These results showcase the GRCM’s capability for accurately reproducing the thermal characteristics of PCM-HXs with considerably lower computational effort.

42 ENGINEERING↗
DOE OSTI2024

Glassy embedded solid-state electrode assemblies, solid-state batteries and methods of making electrode assemblies and solid-state batteries

Batteries, component structures and manufacturing methods, in particular including a glassy embedded battery electrode assembly having a composite material structure composed of interpenetrating material components including a porous electroactive network including a solid electroactive material, and a continuous glassy medium including a Li ion conducting sulfide glass, can achieve enhanced power output, reduced charging time and/or improved cycle life.

Visco, Steven J.↗
DOE OSTI2024

Three-dimensional airgap electric machines employing winding embedded liquid cooling

Various examples are provided related to 3D airgap electric machines and winding embedded liquid cooling. In one example, an electric machine includes a stator assembly with stator windings supported by a stator core and an outer rotor assembly includes a radial plate surrounding the stator assembly and an endplate at a first end of the radial plate adjacent to the first end of the stator core. The stator windings can include a first portion extending along an axial length of the stator core and a second portion at a first end of the stator core that extends radially inward towards a shaft of the electric machine. The radial plate can include magnets distributed about the radial plate. In another example, a stator assembly includes stator windings supported by a stator core with a winding support including cooling channels distributed between the stator windings. The winding support can be nonmagnetic.

Islam, Md Sariful↗
DOE OSTI2025

Frequency Control and Disturbance Containment Using Grid-Forming Embedded Storage Networks

The paper presents a distributed approach for operating a network of inverter-based energy storage resources embedded in a bulk power system. Departing from their traditional role of steady-state reserves, the storage assets in the network are utilized as frequency-responsive resources shaping system dynamics. The power electronics converter systems interfacing the storage resources are equipped with local controllers designed to respond under transient disturbances. To this end, a safety-constrained distributed control strategy is explored. The paper compares the performance of converter-interfaced grid-forming and grid-following storage networks for fast frequency control and disturbance containment/localization. Sensitivity studies are performed to study the impact of storage size, steady-state dispatch, and controller design on dynamic performance. The findings are presented through case studies with results from the IEEE test systems.

Chatterjee, Kaustav (ORCID:0000000153273860)↗