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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 1,639 records · Page 91
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NASA NTRS2014

Mars Entry Atmospheric Data System Modeling, Calibration, and Error Analysis

The Mars Science Laboratory (MSL) Entry, Descent, and Landing Instrumentation (MEDLI)/Mars Entry Atmospheric Data System (MEADS) project installed seven pressure ports through the MSL Phenolic Impregnated Carbon Ablator (PICA) heatshield to measure heatshield surface pressures during entry. These measured surface pressures are used to generate estimates of atmospheric quantities based on modeled surface pressure distributions. In particular, the quantities to be estimated from the MEADS pressure measurements include the dynamic pressure, angle of attack, and angle of sideslip. This report describes the calibration of the pressure transducers utilized to reconstruct the atmospheric data and associated uncertainty models, pressure modeling and uncertainty analysis, and system performance results. The results indicate that the MEADS pressure measurement system hardware meets the project requirements.

Karlgaard, Christopher D.↗
NASA NTRS2011

Supersonic Retropropulsion Flight Test Concepts

NASA's Exploration Technology Development and Demonstration Program has proposed plans for a series of three sub-scale flight tests at Earth for supersonic retropropulsion, a candidate decelerator technology for future, high-mass Mars missions. The first flight test in this series is intended to be a proof-of-concept test, demonstrating successful initiation and operation of supersonic retropropulsion at conditions that replicate the relevant physics of the aerodynamic-propulsive interactions expected in flight. Five sub-scale flight test article concepts, each designed for launch on sounding rockets, have been developed in consideration of this proof-of-concept flight test. Commercial, off-the-shelf components are utilized as much as possible in each concept. The design merits of the concepts are compared along with their predicted performance for a baseline trajectory. The results of a packaging study and performance-based trade studies indicate that a sounding rocket is a viable launch platform for this proof-of-concept test of supersonic retropropulsion.

Exploration Technology Development and Demonstrati↗
NASA NTRS2015

[Fall 2015 Abstract by Stephanie Scharf]

This Fall I worked on two different projects that culminated into a redesign of the spacesuit LLB (long life battery). I also did some work on the PLSS (personal life support system) battery with EC. My first project was redlining the work instruction for completing DPAs (destructive physical analysis) on battery cells in the Branch. The purpose of this document is to create a standard process and ensure that the data is collected in the same way, no matter who carries out the analysis. I observed three DPAs, conducted one with help, and conducted two on my own, all while taking notes on the procedure. These notes were used to write the final work instruction, which will become the Branch standard. My second project continued the work of the Summer co-op before me. I tested aluminum heat sinks for their ability to provide good thermal conduction and structural support during a thermal runaway event. The heat sinks had been designed by the previous Summer co-op, but there was not much time for testing before he left. We thus ran tests with a heater on the bottom of a trigger cell to try to drive thermal runaway and ensure that it will not propagate to adjacent cells. We also ran heat-to-vent tests in an oven to see if the assembly provided structural support and prevented sidewall rupture during thermal runaway. These tests were carried out at ESTA (Energy Systems Test Area) and are providing very promising results, indicating that safe, high performing (>180 Wh/kg) designs are possible. My main project was a redesign of the LLB (Lightweight Lithium Battery). Another summer intern had done some testing and concluded that there was no simple fix to mitigate thermal runaway propagation hazards in the existing design. The only option was a clean sheet redesign of the battery. I was given a volume and ideal energy density, and the rest of the design was up to me. First, I created new heat sink banks in CREO, using the information gathered in the metal heat sink tests from the summer intern. After this, I made capture plates to hold the cells in place, and I worked on nickel bussings for the electrical connections between the cells. Finally, I designed the test box enclosure that included sections for flame arresting materials. The battery brick design, which is the heart of the battery, promises to become the first for a manned spacecraft application to achieve > 180 Wh/kg. My work in redlining the DPA work instructions will also be used in selecting the cells for the battery. We had a few options for cells that would provide the necessary power output and needed to make a choice. We repeatedly charged and discharged cells for around a month until they went through 100 lifecycles. The plan was to compare the DPA results on fresh and cycled cells from each manufacturer to see if cycling introduces any differences. After the complete LLB design was approved, the parts were ordered and testing should begin the first week of December. Cutting open a cell for DPA After photo from oven heat-to-vent test

Scharf, Stephanie↗
NASA NTRS2015

Flight Tests of a Supersonic Natural Laminar Flow Airfoil

A flight-test campaign of a supersonic natural laminar flow airfoil has been recently completed. The test surface was an 80-inch (203 cm) chord and 40-inch (102 cm) span article mounted on the centerline store location of an F-15B airplane (McDonnell Douglas Corporation, now The Boeing Company, Chicago, Illinois). The test article was designed with a leading edge sweep of effectively 0 deg to minimize boundary layer crossflow. The test article surface was coated with an insulating material to avoid significant heat transfer to and from the test article structure to maintain a quasi-adiabatic wall. An aircraft-mounted infrared camera system was used to determine boundary layer transition and the extent of laminar flow. The tests were flown up to Mach 2.0 and chord Reynolds numbers in excess of 30 million. The objectives of the tests were to determine the extent of laminar flow at high Reynolds numbers and to determine the sensitivity of the flow to disturbances. Both discrete (trip dots) and 2-D disturbances (forward-facing steps) were tested. A series of oblique shocks, of yet unknown origin, appeared on the surface, which generated sufficient crossflow to affect transition. Despite the unwanted crossflow, the airfoil performed well. The results indicate the sensitivity of the flow to the disturbances, which can translate into manufacturing tolerances, were similar to that of subsonic natural laminar flow wings.

supersonic boundary layer↗
NASA NTRS2016

Crew Exploration Vehicle (CEV) (Orion) Occupant Protection

The purpose of this study was to determine the similarity between the response of the THUMS model and the Hybrid III Anthropometric Test Device (ATD) given existing Wright-Patterson (WP) sled tests. There were four tests selected for this comparison with frontal, spinal, rear, and lateral loading. The THUMS was placed in a sled configuration that replicated the WP configuration and the recorded seat acceleration for each test was applied to model seat. Once the modeling simulations were complete, they were compared to the WP results using two methods. The first was a visual inspection of the sled test videos compared to the THUMS d3plot files. This comparison resulted in an assessment of the overall kinematics of the two results. The other comparison was a comparison of the plotted data recorded for both tests. The metrics selected for comparison were seat acceleration, belt forces, head acceleration and chest acceleration. These metrics were recorded in all WP tests and were outputs of the THUMS model. Once the comparison of the THUMS to the WP tests was complete, the THUMS model output was also examined for possible injuries in these scenarios. These outputs included metrics for injury risk to the head, neck, thorax, lumbar spine and lower extremities. The metrics to evaluate head response were peak head acceleration, HIC15, and HIC36. For the neck, N (sub ij) was calculated. The thorax response was evaluated with peak chest acceleration, the Combined Thoracic Index (CTI), sternal deflection, chest deflection, and chest acceleration- 3 ms clip. The lumbar spine response was evaluated with lumbar spine force. Finally the lower extremity response was evaluated by femur and tibia force. The results of the simulation comparisons indicate the THUMS model had a similar response to the Hybrid III dummy given the same input. The primary difference seen between the two was a more flexible response of the THUMS compared to the Hybrid III. This flexibility was most pronounced in the neck flexion, shoulder deflection and chest deflection. Due to the flexibility of the THUMS, the resulting head and chest accelerations tended to lag the Hybrid III acceleration trace and have a lower peak value. The results of the injury metric comparison identified possible injury trends between simulations. Risk of head injury was highest for the lateral simulations. The risk of chest injury was highest for the rear impact. However, neck injury risk was approximately the same for all simulations. The injury metric value for lumbar spine force was highest for the spinal impact. The leg forces were highest for the rear and lateral impacts. The results of this comparison indicate the THUMS model performs in a similar manner as the Hybrid III ATD. The differences in the responses of model and the ATD are primarily due to the flexibility of the THUMS. This flexibility of the THUMS would be a more human like response. Based on the similarity between the two models, the THUMS should be used in further testing to assess risk of injury to the occupant.

Currie-Gregg, Nancy J.↗
NASA NTRS2017

Numerical and Analytical Assessment of a Coupled Rotating Detonation Engine and Turbine Experiment

An analysis is presented of an experimental rig comprising a rotating detonation engine (RDE) with bypass ejector flow coupled to a downstream turbine. The analysis used a validated computational fluid dynamics RDE simulation combined with straightforward algebraic mixing equations for the bypass flow. The objectives of the analysis were to supplement and interpret the necessarily sparse measurements from the rig, and to assess the performance of the RDE itself, which was not instrumented in this installation. The analysis is seen to agree reasonably well with available data. It shows that the RDE is operating in an unusual fashion, with subsonic flow throughout the exhaust plane. The detonation event itself is producing a total pressure rise relative to the pre-detonative pressure; however, the length of the device and the substantial flow restriction at the inlet yield an overall pressure loss. This is not surprising since the objective of the rig test was primarily aimed at investigating RDE/turbine interactions, and not on performance optimization. Furthermore, the RDE was designed for fundamental detonation studies and not performance. Nevertheless, the analysis indicates that with some small alterations to the design, an RDE with an overall pressure rise is possible.

detonation↗
NASA NTRS2017

Numerical and Analytical Assessment of a Coupled Rotating Detonation Engine and Turbine Experiment

An analysis is presented of an experimental rig comprising a rotating detonation engine (RDE) with bypass ejector flow coupled to a downstream turbine. The analysis used a validated computational fluid dynamics RDE simulation combined with straightforward algebraic mixing equations for the bypass flow. The objectives of the analysis were to supplement and interpret the necessarily sparse measurements from the rig, and to assess the performance of the RDE itself, which was not instrumented in this installation. The analysis is seen to agree reasonably well with available data. It shows that the RDE is operating in an unusual fashion, with subsonic flow throughout the exhaust plane. The detonation event itself is producing a total pressure rise relative to the pre-detonative pressure; however, the length of the device and the substantial flow restriction at the inlet yield an overall pressure loss. This is not surprising since the objective of the rig test was primarily aimed at investigating RDE turbine interactions, and not on performance optimization. Furthermore, the RDE was designed for fundamental detonation studies and not performance. Nevertheless, the analysis indicates that with some small alterations to the design, an RDE with an overall pressure rise is possible.

propulsion↗
NASA NTRS2017

Numerical and Analytical Assessment of a Coupled Rotating Detonation Engine and Turbine Experiment

An analysis is presented of an experimental rig comprising a rotating detonation engine (RDE) with bypass flow coupled to a downstream turbine. The analysis used a validated computational fluid dynamics RDE simulation combined with straightforward algebraic mixing equations for the bypass flow. The objectives of the analysis were to supplement and interpret the necessarily sparse measurements from the rig, and to assess the performance of the RDE itself (which was not instrumented in this installation). The analysis is seen to agree reasonably well with available data. It shows that the RDE is operating in an unusual fashion, with subsonic flow throughout the exhaust plane. The detonation event itself is producing a total pressure rise relative to the pre-detonative pressure; however, the length of the device and the substantial flow restriction at the inlet yield an overall pressure loss. This is not surprising since the objective of the rig test was primarily aimed at investigating RDEturbine interactions, and not on performance optimization. Furthermore, the RDE was designed for fundamental detonation studies and not performance. Nevertheless, the analysis indicates that with some small alterations to the design, an RDE with an overall pressure rise is possible.

detonation↗
NASA NTRS2017

Giovanni in the Cloud: Earth Science Data Exploration in Amazon Web Services

Giovanni is an exploration tool at the NASA Goddard Earth Sciences Data Information Services Center (GES DISC), providing 22 analysis and visualization services for over 1600 Earth Science data variables. Owing to its popularity, Giovanni has experienced a consistent growth in overall demand, with periodic usage spikes attributed to trainings by education organizations, extensive data analysis in response to natural disasters, preparations for science meetings, etc. Furthermore, the new generation of spaceborne sensors and high resolution models have resulted in an exponential growth in data volume with data distributed across the traditional boundaries of data centers. Seamless exploration of data (without users having to worry about data center boundaries) has been a key recommendation of the GES DISC User Working Group. These factors have required new strategies for delivering acceptable performance. The cloud-based Giovanni, built on Amazon Web Services (AWS), evaluates (1) AWS native solutions to provide a scalable, serverless architecture; (2) open standards for data storage in the Cloud; (3) a cost model for operations; and (4) end-user performance. Our preliminary findings indicate that the use of serverless architecture has a potential to significantly reduce development and operational cost of Giovanni. The combination of using AWS managed services, storage of data in open standards, and schema-on-read data access strategy simplifies data access and analytics, in addition to making data more accessible to the end users of Giovanni through popular programming languages.

Giovanni↗
NASA NTRS2014

Predicting Ground Delay Program at an Airport Based on Meteorological Conditions

In this paper, we present two supervised-learning models, logistic regression and decision tree, to predict occurrence of ground delay program at an airport based on meteorological conditions and scheduled traffic demand. Such predictive capabilities can help the Federal Aviation Administration traffic managers and airline dispatchers to prepare mitigation strategies to reduce the impact of adverse weather. The models are applied to predict ground delay program occurrence at two major U.S. airports: Newark Liberty Intl. and San Francisco Intl. airports. The logistic regression model estimates the probability that a ground delay program will occur during a given hour. Decision tree, on the other hand, classifies an hour as a ground delay program or not based on the input variables. Results indicate that both models perform significantly better than a purely random prediction of ground delay program occurrence at the two airports. The logistic regression model performs better than the decision tree model. The degree to which various input variables impact the probability of ground delay program vary between the two airports. While the enroute convective weather is a dominant factor causing ground delay programs at New York airports, poor visibility and low cloud ceiling caused by marine stratus are major drivers of ground delay programs at San Francisco Intl. airport.

traffic flow management↗
NASA NTRS2018

Frequency-Domain Deconvolution for Flight Dynamics Applications

A deconvolution method is presented for estimating input data from measured output data and a model of the dynamic process involved. The method uses an optimal Wiener filter for separating the measured data into signal and noise components, and a high-accuracy Fourier transform for inverting the model dynamics in the frequency domain. The method is an extension of optimal Fourier smoothing, and uses a technique to enhance the contrast between the signal and noise spectra in designing the Wiener filter. The deconvolution method was applied to simulation and flight test data for the purposes of removing unwanted distortions introduced by signal-conditioning filters and sensor dynamics, and for reconstructing turbulence inputs from measured sensor data. Results indicated hat the method performs well given good signal-to-noise levels and accurate models of the dynamic process.

Grauer, Jared A.↗
NASA NTRSDate not supplied

TPSAS-NF1676L-18030-DND

This study investigated the relative acceptance of different avionics implementations that present Flightdeck Interval Management (FIM) speeds and speed deviations to commercial pilots, and for indications of conditions that require action. Each crew evaluated four Avionics conditions: (1) Integrated in which the FIM target speed was presented in the upper left corner of the primary flight display (PFD) and speed profile deviation information was implicitly indicated as the deviation between current speed and an instantaneous speed profile bug on the PFD speed tape. In this Avionics condition, clearance information would have been entered, and could be referenced, on the FIM page in the MCDU. This page also gave a digital readout of speed profile deviation. Significant deviations from the speed profile triggered a message on the EICAS system. (2) EFB-Aft in which an aft-mounted EFB was used as the device housing the FIM algorithm and presented all the relevant information for the operation, including speed targets, speed deviation information, and all elements of the IM clearance. Significant deviations from the speed profile triggered messages on the same EFB display. (3) EFB-Fore in which the same information was presented as in the EFB-Aft condition, but the display was mounted in a more forward location, just under the outboard window. (4) EFB-Aft-AGD in which the EFB-Aft condition was augmented with the ADS-B Guidance Display (AGD). The AGD repeats the same FIM target speed and speed deviation information provided on the EFB. This study compares the efficacy of these Avionics Conditions as well as three methods of annunciating FIM events (a new speed, a reminder that a new speed occurred, and a deviation from the FIM speed profile), using only visual indications, visual indications and an aural for all events, or visual indications for all events plus an aural for speed deviations only. Results show clear preference for the Integrated condition and the use of aural indications. Other metrics of performance using these conditions and methods are mixed.

Kara Latorella↗
NASA NTRS2020

Drop Size Distribution Measurements in Outer Rainbands of Hurricane Dorian at the NASA Wallops Precipitation-Research Facility

Hurricane rainbands are very efficient rain producers, but details on drop size distributions are still lacking. This study focuses on the rainbands of hurricane Dorian as they traversed the densely instrumented NASA precipitation-research facility at Wallops Island, VA, over a period of 8 h. Drop size distribution (DSD) was measured using a high-resolution meteorological particle spectrometer (MPS) and 2D video disdrometer, both located inside a double-fence wind shield. The shape of the DSD was examined using double-moment normalization, and compared with similar shapes from semiarid and subtropical sites. Dorian rainbands had a superexponential shape at small normalized diameter values similar to those of the other sites. NASA’s S-band polarimetric radar performed range height-indicator (RHI) scans over the disdrometer site, showing some remarkable signatures in the melting layer (bright-band reflectivity peaks of 55 dBZ, a dip in the copolar correlation to 0.85 indicative of 12–15 mm wet snow, and a staggering reflectivity gradient above the 0 °C level of −10 dB/km, indicative of heavy aggregation). In the rain layer at heights < 2.5 km, polarimetric signatures indicated drop break-up as the dominant process, but drops as large as 5 mm were detected during the intense bright-band period.

Merhala Thurai↗
NASA NTRS2021

Improved Estimates of Pentad Precipitation through the Merging of Independent Precipitation Datasets

Three independent, quasi-global, gridded datasets of precipitation (a rain gauge-based dataset, the satellite-only component of the NASA Integrated Multi-satellitE Retrievals for Global Precipitation Measurement mission [IMERG] Final Run precipitation product, and precipitation estimates derived from NASA Soil Moisture Active Passive [SMAP] soil moisture retrievals), are objectively combined into a single pentad precipitation dataset at 36-km resolution using a unique approach based on extended triple collocation. The quality of each of the four datasets is then evaluated against independent observations. When a global land surface model at 36-km resolution is integrated four times, once utilizing the merged precipitation forcing and once with each of the three contributing datasets, the near-surface soil moisture variations produced with the merged forcing validate best against independent satellite-based soil moisture fields. In addition, the merged dataset is found to be more consistent, relative to each contributor, with estimates of air temperature variations across the globe. The merged dataset thus appears to draw successfully on the complementary strengths of each contributor: the particularly high quality of the rain gauge-based dataset in areas of high gauge density, the more uniform accuracy across the globe of the IMERG data, and the moderate accuracy, particularly in semi-arid regions, of the soil moisture retrieval-based data. Plain Language Summary Obtaining measurements of precipitation across the globe can be challenging. Rain gauges in some ways provide the most accurate measurements, but gauges are absent in many parts of the world, and even where they exist, they only measure precipitation at the gauge itself and therefore may not provide an accurate large-scale average. Satellite-based estimates of precipitation largely overcome these problems, but such data have their own issues, notably a “snapshot” (rather than a time-average) character of the measurements and difficulty associated with interpreting the measured radiances in the presence of complex land surfaces. In the present paper, we use a novel approach to generate a “merged” dataset, one that optimally combines the gauge precipitation information and the satellite-based precipitation information with a third set of estimates derived from soil moisture retrievals. The merged precipitation dataset and each of the three contributors (aggregated here to 5-day averages at a spatial resolution of about 36-km) are then evaluated for consistency with independent geophysical fields. The merged dataset is found to perform best, a clear indication that it takes proper advantage of the complementary strengths of each contributor and, accordingly, that the presented approach for merging the different contributors is indeed viable.

Precipitation↗
NASA NTRS2022

Global Gridded Crop Models Underestimate Yield Responses to Droughts and Heatwaves

Extreme events can lead to crop yield declines, resulting in financial losses and threats to food security, and the frequency and intensity of such events is projected to increase. As global gridded crop models (GGCMs) are commonly used to assess climate change impacts on agricultural yields, there is a need to understand whether these models are able to reproduce the observed yield declines. We evaluated 13 GGCMs from the Inter-Sectoral Impact Model Intercomparison Project and compared observed and simulated impact of past droughts and heatwaves on yields for four crops (maize, rice, soy, wheat). We found that most models detect but underestimate the impact of droughts and heatwaves on yield. Specifically, the drought signal was detected by 12 of 13 models for maize and all models for wheat, while the heat signal was detected by eleven models for maize and six models for wheat. To investigate whether the difference between simulated and observed yield declines is due to a misrepresentation of simulated exposure to heat or water scarcity (i.e. misrepresentation of growing season), we analysed the relationship between average discrepancies between observed and simulated yield losses, and average simulated exposure to extreme weather conditions across all crop models. We found a positive correlation between simulated exposure to heat and model performance for heatwaves, but found no correlation for droughts. This suggests that there is a systematic underestimation of yield responses to heat and drought and not only a misrepresentation of exposure. Assuming that performance for the past indicates models' capacity to project future yield impacts, models likely underestimate future yield decline from climate change. High-quality temporally and spatially resolved observational data on growing seasons will be highly valuable to further improve crop models' capacity to adequately respond to extreme weather events.

extreme events↗
NASA NTRSDate not supplied

Challenges in Understanding Radiation Belt Dynamics: Insights from Two Storm Periods

The periods of May 27 - June 5, 2017 and Oct 24 — 29, 2016 are 'unusual' in terms of radiation belt dynamics and their solar wind driving conditions. The first period was under the influence of a slow CME-led major geomagnetic storm with Dstmin = -125 nT and the second period was under high speed solar wind streams. Observations from Van Allen Probes show great variabilities in different electron energy channels for both periods. During the second period of Oct 24 - 29, 2016, electron fluxes are found to be near the highest upper limit among various storms during 2013–2018 (Hua, Bortnik and Ma, 2022). In this paper, we provide solar wind sources and geomagnetic conditions for these two storm periods and point out challenges in understanding, modeling, and forecasting radiation belt dynamics. In-depth analysis of modeling results utilizing radiation belt models available at the Community Coordinated Modeling Center such as VERB and CIMI will be performed. Initial modeling results indicate rather large discrepancies with the observations. Model validation using different metrics introduced in Zheng et al. (2019) will be carried out to gain a deeper understanding of the physical processes involved and to identity potential causes of modeling inadequacies.

Yihua Zheng↗
NASA NTRSDate not supplied

International Space Station Acoustics – A Status Report

It is important to control acoustic noise aboard the International Space Station (ISS) to provide a satisfactory environment for voice communications, alarm audibility, and restful sleep, and to minimize the risk for hearing loss. Acoustic monitoring is an important part of the noise control process on ISS, providing critical data for trend analysis, noise exposure analysis, validation of acoustic analyses and predictions, and to provide strong evidence for ensuring crew health and safety, thus allowing Flight Certification. And since the primary noise sources on ISS include the environmental control and life support system’s air revitalization system (fans and airflow) and active thermal control system (pumps and water flow), acoustic monitoring will indicate changes in hardware noise emissions that may indicate system degradation or performance issues. This paper provides the current acoustic levels in the ISS modules and sleep stations, and is an update to the status presented in 2018. Since this last status report, noise levels have remained consistent, but issues with stalled fan noise and unexplained low frequency spectral peaks have caused some exceedances to requirements. Noise levels in the Russian Segment have either remained consistent or have been reduced slightly, except for the new Multipurpose Laboratory Module, which has some significant noise exceedances.

Christopher S Allen↗
NASA NTRS2024

Herpesviruses in Saliva and Their Clinical Significance

Saliva has been used as a source of biological markers for a wide spectrum of normal and disease states for a long time. It is a non-invasive, easily accessible, and self-collected body fluid that contains a variety of measurable biological substances. While mostly water, saliva also contains ions, carbohydrates, proteins and peptides, exfoliated cells, nucleic acids, and microorganisms. Saliva can reflect tissue levels of some natural substances and a large variety of molecules introduced for therapeutic use, emotional status; hormonal status, immunological status, neurological effects, and nutritional and metabolic status. It can also be used to monitor a variety of drugs including marijuana, cocaine, and alcohol. It is the most cost-effective approach for screening large population in community mass screening programs and for longitudinal sampling of hospitalized individuals aimed at monitoring viral load dynamics and treatment response. During the COVID-19 pandemic, scientific evidence emerged indicating that molecular tests performed on saliva have diagnostic sensitivity and specificity comparable to those observed with nasopharyngeal swabs for SARS-CoV-2 RNA detection. The presence of IgA and IgG antibodies at the mucosal level has been demonstrated to influence the progression of viral infection and the severity of clinical manifestation. As saliva contains both respiratory secretions and immunological components, it has wide applications, ranging from clinical diagnostics to post-vaccine disease burden and immunity surveillance.

Douglass Diak↗