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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

LightMat Seedling Project: Enabling the Development of High Strength Magnesium Alloy Sheet for Light-Weighting Applications

It is well known that a 10% reduction in vehicle weight can result in a 6-8% fuel economy improvement in gasoline/diesel vehicles. Replacing steel and aluminum with magnesium can result in weight savings between 25 and 75% and hence magnesium alloys have been considered for multiple body-in-white components to reduce the weight of the glider. For example, magnesium sheet has been considered for decklid inner panels, rear seatback panels, roof panels, and door inners.

36 MATERIALS SCIENCE↗
NASA NTRS1992

Fiber optic-based laser vapor screen flow visualization systems for aerodynamic research in larger-scale subsonic and transonic wind tunnels

The design, installation, and application of the NASA laser vapor screen (LVS) flow visualization systems developed by 10-foot high speed tunnel and 8-foot transonic pressure tunnel are discussed. Sufficient quantity of water is injected into the wind tunnel diffuser section to increase the relative humidity and promote condensation of the water vapor in the flow field about the model. Vortex-dominated flows are illuminated with an intense sheet of laser light. Fiber optics are used to deliver the laser beam through the plenum shell that surrounds the test section of each facility and to the light sheet-generating optics positioned in the ceiling window of the test section. Operational experience indicates that fiber optic-based systems are safe, reliable, and capable of proving high-quality off-surface flow visualization in larger scale subsonic and transonic wind tunnels.

Erickson, Gary E.↗
NASA NTRS1999

Optical Flow-Field Techniques Used for Measurements in High-Speed Centrifugal Compressors

The overall performance of a centrifugal compressor depends on the performance of the impeller and diffuser as well as on the interactions occurring between these components. Accurate measurements of the flow fields in each component are needed to develop computational models that can be used in compressor design codes. These measurements must be made simultaneously over an area that covers both components so that researchers can understand the interactions occurring between the two components. Optical measurement techniques are being used at the NASA Lewis Research Center to measure the velocity fields present in both the impeller and diffuser of a 4:1 pressure ratio centrifugal compressor operating at several conditions ranging from design flow to surge. Laser Doppler Velocimetry (LDV) was used to measure the intrablade flows present in the impeller, and the results were compared with analyses obtained from two three-dimensional viscous codes. The development of a region of low throughflow velocity fluid within this high-speed impeller was examined and compared with a similar region first observed in a large low-speed centrifugal impeller at Lewis. Particle Image Velocimetry (PIV) is a relatively new technique that has been applied to measuring the diffuser flow fields. PIV can collect data rapidly in the diffuser while avoiding the light-reflection problems that are often encountered when LDV is used. The Particle Image Velocimeter employs a sheet of pulsed laser light that is introduced into the diffuser in a quasi-radial direction through an optical probe inserted near the diffuser discharge. The light sheet is positioned such that its centerline is parallel to the hub and shroud surfaces and such that it is parallel to the diffuser vane, thereby avoiding reflections from the solid surfaces. Seed particles small enough to follow the diffuser flow are introduced into the compressor at an upstream location. A high-speed charge-coupled discharge (CCD) camera is synchronized to the laser pulse rate; this allows it to capture images of seed particle position that are separated by a small increment in time. A crosscorrelation of a particle's position in two consecutive images provides an estimate of flow velocity and direction. Multiple image pairs obtained in rapid succession at a particular flow condition provide enough measurements for statistical significance. PIV provides simultaneous velocity measurements over the entire plane that is illuminated by the light sheet instead of at a single point, as is the case when LDV is used. PIV has a further advantage in that the laser light pulse can be triggered by an external source such as a high-response pressure transducer. This feature will allow PIV to synchronize flow imaging to physical phenomena such as rotating stall or stall precursor waves. We hope that this technique can be used to obtain images of the flow field during and just prior to stall.

Skoch, Gary J.↗
NASA NTRS1991

System for determining position of normal shock in supersonic flow

Light from a plurality of light emitting diodes is transmitted through optical cables (12) to a lens system. The lenses (56, 58) expand and collimate the light and project it in a sheet (16) across the supersonic inlet of an aircraft power plant perpendicular to incoming airflow. A normal shock bends a portion of the sheet of light (16). A linear array of a multiplicity of optical fiber ends collects discrete samples of light. The samples are processed and compared to a predetermined profile to determine the shock location.

Iverson, Jr., Donald G.↗
NASA NTRS1990

Aerodynamics support of research instrument development

A new velocimetry system is currently being developed at NASA LaRC. The device, known as a Doppler global velocimeter (DGV), can record three velocity components within a plane simultaneously and in near real time. To make measurements the DGV, like many other velocimetry systems, relies on the scattering of light from numerous small particles in a flow field. The particles or seeds are illuminated by a sheet of laser light and viewed by two CCD cameras. The scattered light from the particles will have a frequency which is a function of the source laser light frequency, the viewing angle, and most importantly the seed velocities. By determining the scattered light intensity the velocity can be measured at all points within the light sheet simultaneously. Upon completion of DGV component construction and initial check out a series of tests in the Basic Aerodynamic Research (wind) Tunnel (BART) are scheduled to verify instrument operation and accuracy. If the results are satisfactory, application of the DGV to flight measurements on the F-18 High Alpha Research Vehicle (HARV) are planned. The DGV verification test in the BART facility will utilize a 75 degree swept delta wing model. A major task undertaken this summer included evaluation of previous results for this model. A specific series of tests matching exactly the previous tests and exploring new DGV capabilities were developed and suggested. Another task undertaken was to study DGV system installation possibilities in the F-18 HARV aircraft. In addition, a simple seeding system modification was developed and utilized to make Particle Imaging Velocimetry (PIV) measurements in the BART facility.

Miller, L. Scott↗
NASA NTRS2020

Measuring Multiple Cosmogenic Nuclides in Glacial Cobbles Sheds Light on Greenland Ice Sheet Processes

The extent and erosivity of the Greenland Ice Sheet during the Pleistocene remain uncertain due to the paucity of evidence predating the Last Glacial Maximum. Here, we employ a novel approach, cosmogenic nuclide analysis of individual subglacial cobbles, which allows us to infer the behavior of the ice sheet over time and space. From three locations in western Greenland, we collected 86 cobbles from the current ice sheet margin and nine cobbles exposed on the modern proglacial land surface. We measured the concentration of in situ 10Be in all cobbles (n= 95) and 26Al and 14C in a subset (n= 14). Cobbles deposited during Holocene retreat have 10Be exposure ages generally consistent with the timing of ice retreat determined by other means. Conversely, most of the 86 subglacial cobbles contain very low concentrations of 10Be (median 1.0 x 10^3 atoms g-1), although several have ~10^4 and one has ~10^5 atoms g-1. The low concentrations of 10Be in most subglacial cobbles imply that their source areas under the Greenland Ice Sheet are deeply eroded, preserving minimal evidence of surface or near-surface exposure. The presence of measurable 14C in ten of the cobbles requires that they experienced cosmogenic nuclide production within the past ~30 ka; however, 14C/10Be ratios of ~6 suggest that production occurred beneath thin overlying rock, sediment, and/or ice, where the muon component of 14C production dominates. Only two of the 86 subglacial cobbles definitively have cosmogenic nuclide concentrations consistent with prior surface exposure during times of reduced ice extent. Overall, isotopic analysis of subglacial cobbles indicates that western Greenland's subglacial landscape is characterized by deep erosion and minimal subaerial exposure.

Pliocene↗
NASA NTRS2020

Measuring multiple cosmogenic nuclides in glacial cobbles sheds light on Greenland Ice Sheet processes

The behavior of the Greenland Ice Sheet during the Pleistocene remains uncertain due to the paucity of evidence predating the Last Glacial Maximum. Here, we employ a novel approach, cosmogenic nuclide analysis of individual subglacially-derived cobbles, which allows us to make inferences about ice sheet processes and subglacial erosion. From three locations in western Greenland, we collected 86 cobbles from the current ice sheet margin and nine cobbles exposed on the modern proglacial land surface. We measured the concentration of in situ 10Be in all cobbles (n =95) and 26Al and 14C in a subset (n =14). Cobbles deposited during Holocene retreat have 10Be exposure ages generally consistent with the timing of ice retreat determined by other methods. Conversely, most of the 86 subglacial cobbles contain very low concentrations of 10Be (median 1.0×10^3atoms/g), although several have ∼104and one has ∼10^5atoms/g. The low concentrations of 10Be in most subglacial cobbles imply that their source areas under the Greenland Ice Sheet are deeply eroded, preserving minimal evidence of surface or near-surface exposure. The presence of measurable 14C in ten of the cobbles requires that they experienced cosmogenic nuclide production within the past ∼30 ka; however, 14C/10Be ratios of ∼6 suggest that nuclide production occurred during shielding by overlying material. Only two of the 86 subglacial cobbles definitively have cosmogenic nuclide concentrations consistent with prior surface exposure. Overall, isotopic analysis of subglacial cobbles indicates that much of western Greenland’s subglacial landscape is characterized by deep erosion and minimal subaerial exposure.

cosmogenic nuclides↗
NASA NTRS1996

Retroreflection Focusing Schlieren System

A retroreflective type focusing schlieren system which permits the light source to be positioned on the optic side of the system is introduced. The system includes an extended light source, as opposed to a point source, located adjacent to a beam splitter which projects light through the flow field onto a reflecting grating in the form of a grid which generates sheets of light that are directed back through the flow field and the beam splitter onto a primary lens behind which is located a cut-off grid having a grid pattern which corresponds to the grid pattern of the reflecting grating. The cut-off grid is adjustably positioned behind the primary lens and an image plane for imaging the turbulence is adjustably located behind the cut-off grid.

Heineck, James T.↗
NASA NTRS2010

Low Mass Printable Devices for Energy Capture, Storage, and Use

The energy-efficient, environmentally friendly technology that will be presented is the result of a Space Act Agreement between NthDegree Technologies Worldwide, Inc., and the National Aeronautics and Space Administration's (NASA's) Marshall Space Flight Center (MSFC). The work combines semiconductor and printing technologies to advance lightweight electronic and photonic devices having excellent potential for commercial and exploration applications. Device development involves three projects that relate to energy generation and consumption: (1) a low-mass efficient (low power, low heat emission) micro light-emitting diode (LED) area lighting device; (2) a low-mass omni-directional efficient photovoltaic (PV) device with significantly improved energy capture; and (3) a new approach to building super-capacitors. These three technologies, energy capture, storage, and usage (e.g., lighting), represent a systematic approach for building efficient local micro-grids that are commercially feasible; furthermore, these same technologies, appropriately replacing lighting with lightweight power generation, will be useful for enabling inner planetary missions using smaller launch vehicles and to facilitate surface operations during lunar and planetary surface missions. The PV device model is a two sphere, light trapped sheet approximately 2-mm thick. The model suggests a significant improvement over current thin film systems. For lighting applications, all three technology components are printable in-line by printing sequential layers on a standard screen or flexographic direct impact press using the three-dimensional printing technique (3DFM) patented by NthDegree. One primary contribution to this work in the near term by the MSFC is to test the robustness of prototype devices in the harsh environments that prevail in space and on the lunar surface. It is anticipated that this composite device, of which the lighting component has passed off-gassing testing, will function appropriately in such environments consistent with NASA s exploration missions. Advanced technologies such as this show promise for both space flight and terrestrial applications.

Frazier, Donald O.↗
NASA NTRS1982

'Light bar' attitude indicator

The development and evaluation of a light bar attitude indicator to help maintain proper aircraft attitude during high altitude night flying is described. A standard four-inch ADI was modified to project an artificial horizon across the instrument panel for pitch and roll information. A light bulb was put in the center of the ADI and a thin slit cut on the horizon, resulting in a thin horizontal sheet of light projecting from the instrument. The intensity of the projected beam is such that it can only be seen in a darkened room or at night. The beam on the instrument panel of the T-37 jet trainer is shown, depicting various attitudes. The favorable comments of about 50 pilots who evaluated the instrument are summarized, including recommendations for improving the instrument. Possible uses for the instrument to ease the pilot task are listed. Two potential problems in using the device are the development of pilot complacency and an upright-inverted ambiguity in the instrument.

Enevoldson, E. K.↗
NASA NTRS2003

High Resistivity Transparent/Conductive Coatings for Space Applications: Problems and Possible Improvements

We have prepared transparent films with a sheet relativity of 10(exp 1) to 10(exp 12) ohm/square by co-depositing a transparent conducting oxide (TCO) with magnesium fluoride, using two independently controlled RF magnetron sputter guns to facilitate adjustment of the film composition, Co-deposited indium tin oxide (ITO) and MgF2 on quartz and flexible polymeric substrate exhibited reasonably stable sheet resistivity over several months' time, with substantially lower optical reflectance than that of pure ITO. However, exposure to low-intensity blue light reduces sheet resistivity by as much as two orders of magnitude. Our results suggest this photoconductivity effect may be present in all InO(x)-based materials. We find that sheet resistivity can by "tuned" by admitting a small amount of high-purity air during deposition offering the possibility of closed loop process control.

Cashman, Thomas↗
NASA NTRS2010

Low Mass Printable Devices for Energy Capture, Storage, and Use for Space Exploration Missions

The energy-efficient, environmentally friendly technology that will be presented is the result of a Space Act Agreement between -Technologies Worldwide, Inc., and the National Aeronautics and Space Administration s (NASA s) Marshall Space Flight Center (MSFC). This work combines semiconductor and printing technologies to advance lightweight electronic and photonic devices having excellent potential for commercial and exploration applications, and is an example of industry and government cooperation that leads to novel inventions. Device development involves three energy generation and consumption projects: 1) a low mass efficient (low power, low heat emission) micro light-emitting diode (LED) area lighting device; 2) a low-mass omni-directional efficient photovoltaic (PV) device with significantly improved energy capture; and 3) a new approach to building supercapacitors. These three technologies - energy capture, storage, and usage (e.g., lighting) - represent a systematic approach for building efficient local micro-grids that are commercially feasible; furthermore, these same technologies will be useful for lightweight power generation that enables inner planetary missions using smaller launch vehicles and facilitates surface operations. The PV device model is a two-sphere, light-trapped sheet approximately 2-mm thick. The model suggests a significant improvement over current thin film systems. All three components may be printed in line by printing sequential layers on a standard screen or flexographic direct impact press using the threedimensional printing technique (3DFM) patented by NthDegree. MSFC is testing the robustness of prototype devices in the harsh space and lunar surface environments, and available results will be reported. Unlike many traditional light sources, this device does not contain toxic compounds, and the LED component has passed stringent off-gassing tests required for potential manifesting on spacecraft such as the International Space Station. Future exploration missions will benefit from "green" technology lighting devices such as this, which show great promise for both terrestrial use and space missions.

Frazier, Donald O.↗
NASA NTRS1975

Landsat survey of near-shore ice conditions along the Arctic coast of Alaska

The author has identified the following significant results. Comparison of late season U-2 color infrared sea ice photography and early ice season LANDSAT sea ice imagery has made possible the identification of subtle features seen on early season LANDSAT imagery in the near shore areas. The U-2 imagery positively linked these features to ice conditions generally not observable by LANDSAT because of the time of year when they take place. Ice formed in place largely as single sheets appears light while ice deformed by considerable rafting appears darker when viewed on LANDSAT imagery. Because the ice is snow-covered at the time this imagery is obtained, this underlying structure must be revealed by the topography of the snow surface, and the resulting light scattering characteristics.

Stringer, W. J.↗
NASA NTRS1985

Velocity selective flow visualization in a free supersonic nitrogen jet with the resonant Doppler velocimeter

The use of the resonant Doppler velocimeter for flow visualization in a free supersonic nitrogen jet is demonstrated experimentally. In the experiment reported here, room-temperature nitrogen at 12.7 psi expands through a Mach 3.4 converging diverging nozzle into a plenum chamber; small amount of sodium is injected through a heated needle centered 0.5-in. upstream of the nozzle throat. The beam of a single frequency dye laser is expanded into a sheet of light with a cylindrical beam expander and directed counter to the jet to spatially resolve any slice across the core of the flow. By tuning the laser to different frequencies, particular velocity and density fields can be highlighted.

Zimmermann, M.↗
NASA NTRS1986

Quantitative determination of engine water ingestion

This paper describes a novel non-intrusive optical technique for determination of liquid mass flux in a droplet laden airstream. The technique was developed for quantitative determination of engine water ingestion resulting from heavy rain or wheel spray. Independent measurements of the liquid water content (LWC) of the droplet laden aircraft and of the droplet velocities were made at the simulated nacelle inlet plane for the liquid mass flux determination. The liquid water content was measured by illuminating and photographing the droplets contained within a thin slice of the flow field by means of a sheet of light from a pulsed YAG laser. A fluorescent dye introduced in the water greatly improved the droplet image definition. The droplet velocities were determined from double exposed photographs of the moving droplet field. The technique was initially applied to a steady spray generated in a wind tunnel. It was found that although the spray was initially steady, the aerodynamic breakup process was inherently unsteady. This resulted in a wide variation of the instantaneous liquid water content of the droplet laden airstream. The standard deviation of ten separate LWC measurements was 31 percent of the average. However, the liquid mass flux calculated from the average LWC and droplet velocities came within 10 percent of the known water ingestion rate.

Parikh, P.↗
NASA NTRS1986

Quantitative determination of engine water ingestion

A nonintrusive optical technique is described for determination of liquid mass flux in a droplet laden airstream. The techniques were developed for quantitative determination of engine water ingestion resulting from heavy rain or wheel spray. Independent measurements of the liquid water content (LWC) of the droplet laden airstream and of the droplet velocities were made at the stimulated nacelle inlet plane for the liquid mass flux determination. The LWC was measured by illuminating and photographing the droplets contained within a thin slice of the flow field by means of a sheet of light from a pulsed laser. A fluorescent dye introduced in the water enchanced the droplet image definition. The droplet velocities were determined from double exposed photographs of the moving droplet field. The technique was initially applied to a steady spray generated in a wind tunnel. It was found that although the spray was initially steady, the aerodynamic breakup process was inherently unsteady. This resulted in a wide variation of the instantaneous LWC of the droplet laden airstream. The standard deviation of ten separate LWC measurements was 31% of the average. However, the liquid mass flux calculated from the average LWC and droplet velocities came within 10% of the known water ingestion rate.

Parikh, P.↗
NASA NTRS1989

A laser based computer aided non-intrusive technique for full field flow characterization in macroscopic curved channels

This paper presents the application of a laser based, computer aided image processing technique for the nonintrusive evaluation of field velocities and accelerations in a 180 deg curved channel geometry, characteristic of inlet passages of the cowls of airbreathing aircraft engines. The method based on the illumination of the test section with a laser generated planar sheet of light, allows microscopic or macroscopic surveillance of fluid flow across or along large cross sections for relatively long (greater than 1 sec) periods of time. The method is Lagrangian in concept and permits identification and tracking of the same particle, thus facilitating construction of more comprehensive trajectories and the calculation of velocities and accelerations.

Braun, M. J.↗
NASA NTRS1989

A high resolution electro-optical displacement measurement system

An improved electrooptical system has been developed to sense wind tunnel model position. The original system using 25.6 mm, 1024-element linear photodiode arrays (PDAs) is being successfully used at a NASA wind tunnel but has a limited range. A new two-channel system using 61.44 mm, 4096-element PDAs has been developed to double the range of vertical and pitch measurement and increase the resolution by 60 percent. The PDAs are illuminated by expanding the beam of a single low power helium neon laser into a collimated sheet of light. An object placed in front of the two parallel PDAs produces a shadow on the array apertures which determines the object's position or size. The system has an overall precision of 12.7 microns and + or - 0.015 degrees in linear and angular measurements.

Schott, Timothy D.↗