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At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS2010

Personal Aircraft Point to the Future of Transportation

NASA's Small Business Innovation Research (SBIR) and Small Business Technology Transfer (STTR) programs, as well as a number of Agency innovations, have helped Duluth, Minnesota-based Cirrus Design Corporation become one of the world's leading manufacturers of general aviation aircraft. SBIRs with Langley Research Center provided the company with cost-effective composite airframe manufacturing methods, while crashworthiness testing at the Center increased the safety of its airplanes. Other NASA-derived technologies on Cirrus SR20 and SR22 aircraft include synthetic vision systems that help pilots navigate and full-plane parachutes that have saved the lives of more than 30 Cirrus pilots and passengers to date. Today, the SR22 is the world's top-selling Federal Aviation Administration (FAA)-certified single-engine airplane.

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NASA NTRS2011

Thermal Optical Properties of Lunar Dust Simulants and Their Constituents

The total reflectance spectra of lunar simulant dusts (less than 20 micrometer particles) were measured in order to determine their integrated solar absorptance (alpha) and their thermal emittance (e) for the purpose of analyzing the effect of dust on the performance of thermal control surfaces. All of the simulants except one had a wavelength-dependant reflectivity (p(lambda)) near 0.10 over the wavelength range of 8 to 25 micrometers, and so are highly emitting at room temperature and lower. The 300 K emittance (epsilon) of all the lunar simulants except one ranged from 0.78 to 0.92. The exception was Minnesota Lunar Simulant 1 (MLS-1), which has little or no glassy component. In all cases the epsilon was lower for the less 20 micrometer particles than for larger particles reported earlier. There was considerably more variation in the lunar simulant reflectance in the solar spectral range (250 to 2500 nanometers) than in the thermal infrared. As expected, the lunar highlands simulants were more reflective in this wavelength range than the lunar mare simulants. The integrated solar absorptance (alpha) of the simulants ranged from 0.39 to 0.75. This is lower than values reported earlier for larger particles of the same simulants (0.41 to 0.82), and for representative mare and highlands lunar soils (0.74 to 0.91). Since the alpha of some mare simulants more closely matched that of highlands lunar soils, it is recommended that and values be the criteria for choosing a simulant for assessing the effects of dust on thermal control surfaces, rather than whether a simulant has been formulated as a highlands or a mare simulant.

Gaier, James R.↗
NASA NTRS2011

Assessing Uncertainties in Boundary Layer Transition Predictions for HIFiRE-1 at Non-zero Angles of Attack

Boundary layer stability was analyzed for the HIFiRE-1 flight vehicle geometry for ground tests conducted at the CUBRC LENS I hypersonic shock test facility and the Langley Research Center (LaRC) 20- inch Mach 6 Tunnel. Boundary layer stability results were compared to transition onset location obtained from discrete heat transfer measurements from thin film gauges during the CUBRC test and spatially continuous heat transfer measurements from thermal phosphor paint data during the LaRC test. The focus of this analysis was on conditions at non-zero angles of attack as stability analysis has already been performed at zero degrees angle of attack. Also, the transition onset data obtained during flight testing was at nonzero angles of attack, so this analysis could be expanded in the future to include the results of the flight test data. Stability analysis was performed using the 2D parabolized stability software suite STABL (Stability and Transition Analysis for Hypersonic Boundary Layers) developed at the University of Minnesota and the mean flow solutions were computed using the DPLR finite volume Navier-Stokes computational fluid dynamics (CFD) solver. A center line slice of the 3D mean flow solution was used for the stability analysis to incorporate the angle of attack effects while still taking advantage of the 2D STABL software suite. The N-factors at transition onset and the value of Re(sub theta)/M(sub e), commonly used to predict boundary layer transition onset, were compared for all conditions analyzed. Ground test data was analyzed at Mach 7.2 and Mach 6.0 and angles of attack of 1deg, 3deg and 5deg. At these conditions, the flow was found to be second mode dominant for the HIFiRE-1 slender cone geometry. On the leeward side of the vehicle, a strong trend of transition onset location with angle of attack was observed as the boundary layer on the leeward side of the vehicle developed inflection points at streamwise positions on the vehicle that correlated to angle of attack. Inflection points are a strong instability mechanism that lead to rapid breakdown and transition to turbulence. The transition onset location on the windward side of the vehicle displayed no trend with angle of attack or freestream Reynolds number and transition was observed farther down the vehicle than observed on the leeward side of the vehicle. In analysis of both windward and leeward sides of the vehicle, use of the N factor methodology to develop trends to predict boundary layer transition onset showed improvements over the Re(sub theta)/M(sub e) empirical correlation methodology. Stronger correlations and less scatter in the data were observed when using the N factor method for these cases.

Marek, Lindsay C.↗
NASA NTRS2011

Thermal Optical Properties of Lunar Dust Simulants and Their Constituents

The total reflectance spectra of lunar simulant dusts (< 20 mm particles) were measured in order to determine their integrated solar absorptance (alpha) and their thermal emittance (epsilon) for the purpose of analyzing the effect of dust on the performance of thermal control surfaces. All of the simulants except one had a wavelength-dependent reflectivity (p (lambda)) near 0.10 over the wavelength range of 8 to 25 microns and so are highly emitting at room temperature and lower. The 300 K emittance (epsilon) of all the lunar simulants except one ranged from 0.78 to 0.92. The exception was Minnesota Lunar Simulant 1 (MLS-1), which has little or no glassy component. In all cases the epsilon was lower for the < 20 micron particles than for larger particles reported earlier. There was considerably more variation in the lunar simulant reflectance in the solar spectral range (250 to 2500 nm) than in the thermal infrared. As expected, the lunar highlands simulants were more reflective in this wavelength range than the lunar mare simulants. The integrated solar absorptance (alpha) of the simulants ranged from 0.39 to 0.75. This is lower than values reported earlier for larger particles of the same simulants (0.41 to 0.82), and for representative mare and highlands lunar soils (0.74 to 0.91). Since the of some mare simulants more closely matched that of highlands lunar soils, it is recommended that and values be the criteria for choosing a simulant for assessing the effects of dust on thermal control surfaces, rather than whether a simulant has been formulated as a highlands or a mare simulant.

Gaier, James R.↗
NASA NTRS2013

Water Treatment Technologies Inspire Healthy Beverages

Mike Johnson, a former technician at Johnson Space Center, drew on his expertise as a wastewater engineer to create a line of kombucha-based probiotic drinks. Unpeeled Inc., based in Minneapolis-St. Paul, Minnesota, employs 12 people and has sold more than 6 million units of its NASA-inspired beverage.

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NASA NTRS2004

Overview 2003 of NASA Multi-D Stirling Convertor Code Development and DOE and NASA Stirling Regenerator R and D Efforts

This paper win report on continuation through the third year of a NASA grant for multi-dimensional Stirling CFD code development and validation; continuation through the third and final year of a Department of Energy, Golden Field Office (DOE), regenerator research effort and a NASA grant for continuation of the effort through two additional years; and a new NASA Research Award for design, microfabrication and testing of a "Next Generation Stirling Engine Regenerator." Cleveland State University (CSU) is the lead organization for all three efforts, with the University of Minnesota (UMN) and Gedeon Associates as subcontractors. The Stirling Technology Company and Sun power, Inc. acted as unfunded consultants or participants through the third years of both the NASA multi-D code development and DOE regenerator research efforts; they win both be subcontractors on the new regenerator microfabrication contract.

Tew, Roy↗
NASA NTRS2014

Smart Sensors Gather Information for Machine Diagnostics

Stennis Space Center was interested in using smart sensors to monitor components on test stands and avert equipment failures. Partnering with St. Paul, Minnesota-based Lion Precision through a Cooperative Agreement, the team developed a smart sensor and the associated communication protocols. The same sensor is now commercially available for manufacturing.

Source record↗
NASA NTRS2014

An Automated Approach to Map the History of Forest Disturbance from Insect Mortality and Harvest with Landsat Time-Series Data

Forests contain a majority of the aboveground carbon (C) found in ecosystems, and understanding biomass lost from disturbance is essential to improve our C-cycle knowledge. Our study region in the Wisconsin and Minnesota Laurentian Forest had a strong decline in Normalized Difference Vegetation Index (NDVI) from 1982 to 2007, observed with the National Ocean and Atmospheric Administration's (NOAA) series of Advanced Very High Resolution Radiometer (AVHRR). To understand the potential role of disturbances in the terrestrial C-cycle, we developed an algorithm to map forest disturbances from either harvest or insect outbreak for Landsat time-series stacks. We merged two image analysis approaches into one algorithm to monitor forest change that included: (1) multiple disturbance index thresholds to capture clear-cut harvest; and (2) a spectral trajectory-based image analysis with multiple confidence interval thresholds to map insect outbreak. We produced 20 maps and evaluated classification accuracy with air-photos and insect air-survey data to understand the performance of our algorithm. We achieved overall accuracies ranging from 65% to 75%, with an average accuracy of 72%. The producer's and user's accuracy ranged from a maximum of 32% to 70% for insect disturbance, 60% to 76% for insect mortality and 82% to 88% for harvested forest, which was the dominant disturbance agent. Forest disturbances accounted for 22% of total forested area (7349 km2). Our algorithm provides a basic approach to map disturbance history where large impacts to forest stands have occurred and highlights the limited spectral sensitivity of Landsat time-series to outbreaks of defoliating insects. We found that only harvest and insect mortality events can be mapped with adequate accuracy with a non-annual Landsat time-series. This limited our land cover understanding of NDVI decline drivers. We demonstrate that to capture more subtle disturbances with spectral trajectories, future observations must be temporally dense to distinguish between type and frequency in heterogeneous landscapes.

Forest↗
NASA NTRS2015

Flight Controller Software Protects Lightweight Flexible Aircraft

Lightweight flexible aircraft may be the future of aviation, but a major problem is their susceptibility to flutter-uncontrollable vibrations that can destroy wings. Armstrong Flight Research Center awarded SBIR funding to Minneapolis, Minnesota-based MUSYN Inc. to develop software that helps program flight controllers to suppress flutter. The technology is now available for aircraft manufacturers and other industries that use equipment with automated controls.

Source record↗
NASA NTRS2015

ASME Section VIII Recertification of a 33,000 Gallon Vacuum-jacketed LH2 Storage Vessel for Densified Hydrogen Testing at NASA Kennedy Space Center

The Ground Operations Demonstration Unit for Liquid Hydrogen (GODU-LH2) has been developed at NASA Kennedy Space Center in Florida. GODU-LH2 has three main objectives: zero-loss storage and transfer, liquefaction, and densification of liquid hydrogen. A cryogenic refrigerator has been integrated into an existing, previously certified, 33,000 gallon vacuum-jacketed storage vessel built by Minnesota Valley Engineering in 1991 for the Titan program. The dewar has an inner diameter of 9.5 and a length of 71.5; original design temperature and pressure ranges are -423 F to 100 F and 0 to 95 psig respectively. During densification operations the liquid temperature will be decreased below the normal boiling point by the refrigerator, and consequently the pressure inside the inner vessel will be sub-atmospheric. These new operational conditions rendered the original certification invalid, so an effort was undertaken to recertify the tank to the new pressure and temperature requirements (-12.7 to 95 psig and -433 F to 100 F respectively) per ASME Boiler and Pressure Vessel Code, Section VIII, Division 1. This paper will discuss the unique design, analysis and implementation issues encountered during the vessel recertification process.

Liquefaction↗
NASA NTRS2017

Space Plants for Astronaut Consumption

Growing plants in space will be an essential part of sustaining astronauts during long-range missions. During the summer of 2017, three female NASA interns, have been engaged in research relevant to food production in space, and will present their projects to an all female program known as Girls in STEM camp. Ayla Grandpre, a senior from Rocky Mountain College, has performed data mining and analysis of crop growth results gathered through Fairchild Botanical Gardens program, Growing Beyond Earth. Ninety plants were downselected to three for testing in controlled environment chambers at KSC. Ayla has also managed an experiment testing a modified hydroponics known as PONDS, to grow mizuna mustard greens and red robin cherry tomatoes. Emma Boehm, a senior from the University of Minnesota, has investigated methods to sterilize seeds and analyzed the most common microbial communities on seed surfaces. She has tested a bleach fuming method and an ethanol treatment. Emma has also tested Tokyo bekana Chinese cabbage seeds from four commercial seed vendors to identity differences in germination and growth variability. Lastly, Payton Barnwell, a junior from Florida Polytechnic University has shown that light recipes provided by LEDs can alter the growth and nutrition of 'Outredgeous' lettuce, Chinese cabbage, and Mizuna. The results of her light quality experiments will provide light recipe recommendations for space crops that grown in the Advanced Plant Habitat currently aboard the International Space Station.

VEGGIE↗
NASA NTRS2015

Development of the US3D Code for Advanced Compressible and Reacting Flow Simulations

Aerothermodynamics and hypersonic flows involve complex multi-disciplinary physics, including finite-rate gas-phase kinetics, finite-rate internal energy relaxation, gas-surface interactions with finite-rate oxidation and sublimation, transition to turbulence, large-scale unsteadiness, shock-boundary layer interactions, fluid-structure interactions, and thermal protection system ablation and thermal response. Many of the flows have a large range of length and time scales, requiring large computational grids, implicit time integration, and large solution run times. The University of Minnesota NASA US3D code was designed for the simulation of these complex, highly-coupled flows. It has many of the features of the well-established DPLR code, but uses unstructured grids and has many advanced numerical capabilities and physical models for multi-physics problems. The main capabilities of the code are described, the physical modeling approaches are discussed, the different types of numerical flux functions and time integration approaches are outlined, and the parallelization strategy is overviewed. Comparisons between US3D and the NASA DPLR code are presented, and several advanced simulations are presented to illustrate some of novel features of the code.

CFD↗
NASA NTRS2017

Dissociation and Internal Excitation of Molecular Nitrogen Due to N + N2 Collisions Using Direct Molecular Simulation

In this work we present a molecular level study of N2+N collisions, focusing on excitation of internal energy modes and non-equilibrium dissociation. The computation technique used here is the direct molecular simulation (DMS) method and the molecular interactions have been modeled using an ab−initio potential energy surface (PES) developed at NASA's Ames Research Center. We carried out vibrational excitation calculations between 5000K and 30000K and found that the characteristic vibrational excitation time for the N + N2 process was an order of magnitude lower than that predicted by the Millikan and White correlation. It is observed that during vibrational excitation the high energy tail of the vibrational energy distribution gets over populated first and the lower energy levels get populated as the system evolves. It is found that the non-equilibrium dissociation rate coefficients for the N + N2 process are larger than those for the N2 + N2 process. This is attributed to the non-equilibrium vibrational energy distributions for the N + N2 process being less depleted than that for the N2 +N2 process. For an isothermal simulation we find that the probability of dissociation goes as 1/T(sub tr) for molecules with internal energy (epsilon(sub int)) less than approximately 9.9eV, while for molecules with epsilon (sub int) greater than 9.9eV the dissociation probability was weakly dependent on translational temperature of the system. We compared non-equilibrium dissociation rate coefficients and characteristic vibrational excitation times obtained by using the ab-initio PES developed at NASA's Ames Research Center to those obtained by using an ab-initio PES developed at the University of Minnesota. Good agreement was found between the macroscopic properties and molecular level description of the system obtained by using the two PESs.

Grover, Maninder S.↗
NASA NTRS2016

Comparison of Quantum Mechanical and Empirical Potential Energy Surfaces and Computed Rate Coefficients for N2 Dissociation

Comparisons are made between potential energy surfaces (PES) for N2 + N and N2 + N2 collisions and between rate coefficients for N2 dissociation that were computed using the quasiclassical trajectory method (QCT) on these PESs. For N2 + N we compare the Laganas empirical LEPS surface with one from NASA Ames Research Center based on ab initio quantum chemistry calculations. For N2 + N2 we compare two ab initio PESs (from NASA Ames and from the University of Minnesota). These use different methods for computing the ground state electronic energy for N4, but give similar results. Thermal N2 dissociation rate coefficients, for the 10,000K-30,000K temperature range, have been computed using each PES and the results are in excellent agreement. Quasi-stationary state (QSS) rate coefficients using both PESs have been computed at these temperatures using the Direct Molecular Simulation of Schwartentruber and coworkers. The QSS rate coefficients are up to a factor of 5 lower than the thermal ones and the thermal and QSS values bracket the results of shock-tube experiments. We conclude that the combination of ab initio quantum chemistry PESs and QCT calculations provides an attractive approach for the determination of accurate high-temperature rate coefficients for use in aerothermodynamics modeling.

quasiclassical trajectory method↗
NASA NTRS2020

Cold-Flow Model Tests to Determine Static Performance of a NASA One-Sided Ejector Nozzle System

This report presents the results of cold-flow model tests to determine the static performance of multiple configurations of a NASA one-sided ejector nozzle system. The existing ejector nozzle system hardware was provided by NASA and was previously used for acoustic tests. A new facility adapter duct and ejector box support brackets were designed and fabricated by the FluiDyne Aerotest Laboratory of Aero Systems Engineering, Inc. The tests were performed in the Channel 8 static thrust stand at ASE’s FluiDyne Aerotest Laboratory in Plymouth, Minnesota. Facility checkout tests were made using a standard American Society of Mechanical Engineers (ASME) long-radius metering nozzle. These tests demonstrated facility data accuracy at flow conditions similar to the model tests. Channel 8 static tests included 40 ASME nozzle facility checkout tests and 24 model tests (plus an additional 1 at no charge). The model nozzle pressure ratio varied from 1.4 to 3.0. Test results include: thrust coefficients, thrust vector angles and location, nozzle discharge coefficients, charging station total and static pressures, and model static pressure distributions (in the Data Appendix).

McDonald, Timothy J.↗
NASA NTRS2020

Streak Instability Analysis for BOLT Configuration

The BOLT configuration designed for an upcoming flight experiment exemplifies the complexities of hypersonic boundary layer transition in the presence of multiple and potentially interacting instability mechanisms. A numerical study of the boundary layer instabilities over this configuration has been performed with the goal of applying state-of-the-art tools in multidimensional stability analysis that complement the other ongoing research related to the BOLT flight campaign. Specifically, the paper outlines modal instability characteristics of the boundary layer streaks adjacent to the minor-axis symmetry plane of a 1/3 rd scale BOLT configuration that was tested in the low-disturbance hypersonic wind tunnel at Purdue University and both quiet and conventional tunnels at Texas A&M University (TAMU). The basic state computations agree well with the heat flux measurements in the Purdue quiet tunnel as well as with the off-body velocity field described in a previous DNS study at the University of Minnesota. The encouraging agreement between the predicted frequency spectra of the streak instability in the region of increased boundary layer thickness and the surface pressure spectra measured during the TAMU experiments suggests that these streak instabilities may play an important role during the transition process near the symmetry plane. The modest value of the predicted peak N-factor (N max ≈ 5) for the streak instabilities provides a potential explanation for why transition is not observed under quiet flow conditions, but may occur in a noisy wind tunnel. Similar instability analyses are performed for the flight configuration at two selected flow conditions from the ascent portion of the planned flight trajectory. The predicted values of the peak N-factor suggest that transition onset in the vicinity of the center plane is possible at the ascent time of t = 26.98 seconds (N max ≈ 12.5 at X/L = 0.77), but the streak instabilities weaken sufficiently at the later time of t = 28.88 seconds (N max ≈ 11.5 at X/L ≈ 1.00) and are less likely to cause transition at that time.

Laminar turbulent transition↗
NASA NTRS2020

Great Lakes Water Resources II: A Google Earth Engine Tool to Automate Wetland Mapping Using Optical and Radar Satellite Sensors in the Great Lakes Basin for Wetland Management and Monitoring

The Great Lakes Basin is one of the world’s largest freshwater ecosystems. The Basin harbors over 200,000 acres of wetlands. These wetlands provide a variety of environmental, ecological, and recreational functions to over 30 million people in the region. Some of these functions include improving water quality, mitigating flood impacts, providing wildlife habitat, and housing recreational activities. However, due to anthropogenic activities, habitat conversion and degradation threaten to disrupt or destroy remaining wetland ecosystems. Maps of wetland distribution based on ground surveys are costly and labor-intensive, prohibiting timely evaluations of wetland loss and gain. The Great Lakes Water Resources II team at the NASA Jet Propulsion Laboratory developed the Wetlands Extent Tool 2.0 (WET 2.0) in Google Earth Engine to automate mapping of wetland distribution in the Great Lakes Basin. The team partnered with the US Fish and Wildlife Service (USFWS), Environmental Protection Agency (EPA), Minnesota Department of Natural Resources (MDNR), the National Oceanic and Atmospheric Administration (NOAA), and Ducks Unlimited (DU). WET 2.0 incorporates Landsat 8 Operational Land Imager (OLI), Sentinel-1 C-band Synthetic Aperture Radar (C-SAR), and Sentinel-2 Multispectral Instrument (MSI) satellite data. WET 2.0 is trained to classify anywhere in the Great Lakes Basin. Utilizing a Random Forest classifier, WET 2.0 is capable of automatically mapping wetland extent in the entire Great Lakes Basin, achieving a mean overall accuracy of 80.12% when tested in Michigan. Findings and maps produced in WET 2.0 will enable our partners to identify areas of ecosystem degradation and wetland destruction in order to enact environmental practices and policy initiatives to maintain environmental and economic health in the area.

Water Resources↗
NASA NTRS2020

Great Lakes Water Resources II: A Google Earth Engine Tool to Automate Wetland Extent Mapping Using Optical and Radar Satellite Sensors in the Great Lakes Basin for Wetland Management and Monitoring

The Great Lakes Basin is one of the world’s largest freshwater ecosystems. The Basin harbors over 200,000 acres of wetlands that provide a variety of environmental, ecological, and recreational functions to over 30 million people in the region. Some of these functions include improving water quality, mitigating flood impacts, providing wildlife habitat, and housing recreational activities. However, due to anthropogenic activities, habitat conversion and degradation threaten to disrupt or destroy remaining wetland ecosystems. Maps of wetland distribution based on ground surveys are costly and labor-intensive, prohibiting timely evaluations of wetland loss and gain. The Great Lakes Water Resources II team at the NASA Jet Propulsion Laboratory developed the Wetlands Extent Tool 2.0 (WET 2.0) in Google Earth Engine to automate mapping of wetland distribution in the Great Lakes Basin. The team partnered with the US Fish and Wildlife Service, Environmental Protection Agency, Minnesota Department of Natural Resources, the National Oceanic and Atmospheric Administration, and Ducks Unlimited. WET 2.0 incorporates Landsat 8 Operational Land Imager (OLI), Sentinel-1 C-band Synthetic Aperture Radar (C-SAR), and Sentinel-2 Multispectral Instrument (MSI) data. Utilizing a Random Forest classifier, WET 2.0 is capable of automatically mapping wetland extent in the entire Great Lakes Basin, achieving a mean overall accuracy of 80.12% when tested in Michigan.Findings and maps produced by WET 2.0 will enable our partners to identify areas of ecosystem degradation and wetland destruction in order to enact environmental practices and policy initiatives to maintain environmental and economic health in the area.

Water Resources↗