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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

A parametric study of staged fuel injector configurations for scramjet applications

A parametric study of staged (multiple) perpendicular fuel injector configurations has been conducted using a computer code which solves the two-dimensional elliptic Navier-Stokes equations. The program computes the turbulent mixing and reaction of hydrogen fuel and air and allows the study of separated regions of the flow immediately preceding and following the injectors. The validity of the code is demonstrated in a cold flow helium injection study with a single injector. Results are presented that describe the flow field near opposing staged injectors over a range of parameters. Parameters that are varied include injector size, fuel split, and distance between injectors. Comparisons of the configurations are made to assess their mixing and potential flame-holding qualities.

Weidner, E. H.↗
NASA NTRS1989

Vortex/boundary layer interactions

Detailed and high quality measurements with hot-wires and pressure probes are presented for two different interactions between a vortex pair with common flow down and a turbulent boundary layer. The interactions studied have larger values of the vortex circulation parameter than those studied previously. The results indicate that the boundary layer under the vortex pair is thinned by lateral divergence and that boundary layer fluid is entrained into the vortex. The effect of the interaction on the vortex core (other than the inviscid effect of the image vortices behind the surface) is small.

Cutler, A. D.↗
NASA NTRS1991

Polarimetry of extreme ultraviolet lines in solar astronomy

Ways are suggested in which recent advancements in the fabrication of ultrasmooth, low scatter flow-polished mirror substrates and high-quality multilayer and interference film coatings can be used to create novel optical instruments for observing linear-polarization effects in the outer solar atmosphere. Attention is given to the observational parameters of all-reflective FUV/EUV imaging polarimeters; such a coronagraph/polarimeter, operating at Ly-alpha, could yield the first measurements of coronal vector magnetic fields.

Fineschi, Silvano↗
NASA NTRSDate not supplied

Integrated Modeling for Payload Test of the Roman Space Telescope

The Nancy Grace Roman Telescope (RST) is a NASA observatory designed to unravel the secrets of dark energy and dark matter, search for and image exoplanets, and explore many topics in infrared optics. Scheduled to launch in no earlier than October 2026, this 2.4 meter aperture telescope has a field of view 100 times greater than the Hubble Space Telescope. The mission is currently in its construction phase, where integrated modeling between thermal, structural, and optical models of the observatory is necessary to demonstrate science quality images over the range of operational parameters. This presentation discusses the most recent integrated modeling analysis cycle for Roman, including model correlation with our instrument level testing. We include a discussion on improved processes of the handling of the various flows of data between the modeling disciplines and discipline specific monte-carlo analysis predictions. We will finish with the predicted uncertainties and expected performance for our upcoming observatory alignment verification test using machine learning algorithms.

telescope↗
NASA NTRS1974

Retransmission of water resources data using the ERTS-1 data collection system

The Water Survey of Canada operates a network of approximately 2400 gauging stations at which water level data are collected. Nine DCPs were installed in isolated areas of northern and western Canada. It was felt that DCPs in these locations would be exposed to climatic conditions severe enough to provide a check on system reliability. Water level data are transmitted from all sites and, also, some of the DCPs are used to transmit ice break-up, water velocity, precipitation, air temperature, water stage recorder clock operation or DCP battery voltage. Consideration is being given to transmitting other parameters that would be of value in flood or flow forecasting. Results of the project have been excellent. There has been no data loss that can be attributed to failure of a DCP although data were lost because of sensor malfunctions. The quality of data collected compares favourably with that of the hard record obtained at the remote sites. Costs of using the ERTS Data Collection System are reasonable.

Halliday, R. A.↗
NASA NTRS1975

Test evaluation of potential heat shield contamination of an Outer Planet Probe's atmospheric sampling system

An Outer Planets Probe which retains the charred heatshield during atmospheric descent must deploy a sampling tube through the heatshield to extract atmospheric samples for analysis. Once the sampling tube is deployed, the atmospheric samples ingested must be free of contaminant gases generated by the heatshield. Outgassing products such as methane and water vapor are present in planetary atmospheres and hence, ingestion of such species would result in gas analyzer measurement uncertainties. This paper evaluates the potential for, and design impact of, the extracted atmospheric samples being contaminated by heatshield outgassing products. Flight trajectory data for Jupiter, Saturn and Uranus entries are analyzed to define the conditions resulting in the greatest potential for outgassing products being ingested into the probe's sampling system. An experimental program is defined and described which simulates the key flow field features for a planetary flight in a ground-based test facility. The primary parameters varied in the test include: sampling tube length, injectant mass flow rate and angle of attack. Measured contaminant levels predict the critical sampling tube length for contamination avoidance. Thus, the study demonstrates the compatibility of a retained heatshield concept and high quality atmospheric trace species measurements.

Kessler, W. C.↗
NASA NTRSDate not supplied

Unsteady Pressure Measurements on a Simplified High-Lift Configuration of the Common Research Model using Active Flow Control

The High-Lift Common Research Model (CRM-HL) is a product of the NASA Advanced Air Transport Technology (AATT) Project intended to study various high-lift aerodynamic phenomena including enhanced lift, acoustic noise generation, and optimum placement of leading and trailing-edge devices. The current study was conducted in the NASA Langley 14-by 22-Foot Subsonic Tunnel (14x22) for the purpose of evaluating enhanced lift through the use of active flow control (AFC). The current paper documents the effect of sweeping-jet actuation combined with steady blowing on a simplified high-lift configuration using unsteady pressure measurements. The time-series parameters for the measurements are documented as well as the data acquisition system used to acquire the data. An uncertainty analysis will be presented in order to document the system performance and provide an estimate of the data quality. Repeatability of the data will be shown along with trends associated with model angle of attack, and also those associated with changes in the nozzle pressure ratio (NPR) of the AFC system.

Active Flow Control↗
NASA NTRS2008

Spray Chemical Vapor Deposition of Single-Source Precursors for Chalcopyrite I-III-VI2 Thin-Film Materials

Thin-film solar cells on flexible, lightweight, space-qualified substrates provide an attractive approach to fabricating solar arrays with high mass-specific power. A polycrystalline chalcopyrite absorber layer is among the new generation of photovoltaic device technologies for thin film solar cells. At NASA Glenn Research Center we have focused on the development of new single-source precursors (SSPs) for deposition of semiconducting chalcopyrite materials onto lightweight, flexible substrates. We describe the syntheses and thermal modulation of SSPs via molecular engineering. Copper indium disulfide and related thin-film materials were deposited via aerosol-assisted chemical vapor deposition using SSPs. Processing and post-processing parameters were varied in order to modify morphology, stoichiometry, crystallography, electrical properties, and optical properties to optimize device quality. Growth at atmospheric pressure in a horizontal hotwall reactor at 395 C yielded the best device films. Placing the susceptor closer to the evaporation zone and flowing a more precursor-rich carrier gas through the reactor yielded shinier-, smoother-, and denser-looking films. Growth of (112)-oriented films yielded more Cu-rich films with fewer secondary phases than growth of (204)/(220)-oriented films. Post-deposition sulfur-vapor annealing enhanced stoichiometry and crystallinity of the films. Photoluminescence studies revealed four major emission bands and a broad band associated with deep defects. The highest device efficiency for an aerosol-assisted chemical vapor deposited cell was one percent.

Hepp, Aloysius F.↗
NASA NTRS2018

Using Remote Sensing Mapping and Growth Response to Environmental Variability to Aide Aquatic Invasive Plant Management

Management of aquatic weeds in complex watersheds and river systems present many challenges to assessment, planning and implementation of management practices for floating and submerged aquatic invasive plants. The Delta Region Areawide Aquatic Weed Project (DRAAWP), a USDA sponsored area-wide project, is working to enhance planning, decision-making and operational efficiency in the California Sacramento-San Joaquin Delta. Satellite and airborne remote sensing are used map (area coverage and biomass density), direct operations, and assess management impacts on plant communities. Archived satellite records enable review of results following previous climate and management events and aide in developing long-term strategies. Examples of remote sensing aiding effectiveness of aquatic weed management will be discussed as well as areas for potential technological improvement. Modeling at local and watershed scales using the SWAT modeling tool provides insight into land-use effects on water quality (described by Zhang in same Symposium). Controlled environment growth studies have been conducted to quantify the growth response of invasive aquatic plants to water quality and other environmental factors. Environmental variability occurs across a range of time scales from long-term climate and seasonal trends to short-term water flow mediated variations. Response time for invasive species response are examined at time scales of weeks, day, and hours using a combination of study duration and growth assessment techniques to assess water quality, temperature (air and water), nitrogen, phosphorus, and light effects. These provide response parameters for plant growth models in response to the variation and interact with management and economic models associated with aquatic weed management. Plant growth models are to be informed by remote sensing and applied spatially across the Delta to balance location and type of aquatic plant, growth response to altered environments and phenology. Initial utilization of remote sensing tools developed for mapping of aquatic invasive plants improved operational efficiency in management practices. These assessment methods provide a comprehensive and quantitative view of aquatic invasive plants communities in the California Delta.

Remote Sensing↗
NASA NTRS2019

Growth Response of Water Hyacinth to Environmental Ranges in the California Sacramento-San Joaquin River Delta

Management of aquatic weeds in complex watersheds and river systems present many challenges to assessment, planning, and implementation of management for aquatic invasive plants. The Delta Region Areawide Aquatic Weed Project (DRAAWP), a USDA sponsored area-wide project including NASA Ames Research Center and State of California Department of Boating and Waterways, is working to enhance decision-making and operational efficiency of invasive plant management in the California Sacramento-San Joaquin Delta. Expansion of invasive aquatic plants has been detrimental to water management and the ecosystem complex in the San Francisco Bay/California Delta. The portion of DRAAWP reported here focuses on parametrizing the environmental response inputs for the Delta models for prominent invasive aquatic plants. Changing climate, long-term drought, shifts in land use, and variation in water flow and quality from input watersheds lead to wide and unique variation in environmental conditions. Environmental variability occurs across a range of time scales from long-term climate and seasonal trends to short-term water flow mediated variations. Response of invasive aquatic plants are examined using controlled environment growth facilities at time scales of weeks, day, and hours using a combination of study duration and growth assessment techniques to assess water quality, temperature, nutrient, and light effects. These provide response parameters for plant growth models in response to the variation and interact with management and economic models associated with aquatic weed management. Plant growth models are informed by remote sensing and applied spatially across the Delta to balance location and type of aquatic plant, growth response to altered environments and phenology.

Sacramento-San Joaquin River Delta.v↗
NASA NTRSDate not supplied

Unsteady Pressure Measurement on a Simplified High-Lift Configuration of the Common Research Model using Active Flow Control

The High-Lift Common Research Model (CRM-HL) is a product of the NASA Advanced Air Transport Technology (AATT) Project intended to study various high-lift aerodynamic phenomena including enhanced lift, acoustic noise generation, and optimum placement of leading and trailing-edge devices. The current study was conducted in the NASA Langley 14-by 22-Foot Subsonic Tunnel (14x22) for the purpose of evaluating enhanced lift through the use of active flow control (AFC). The current paper documents the effect of sweeping-jet actuation combined with steady blowing on a simplified high-lift configuration using unsteady pressure measurements. The time-series parameters for the measurements are documented as well as the data acquisition system used to acquire the data. An uncertainty analysis will be presented in order to document the system performance and provide an estimate of the data quality. Repeatability of the data will be shown along with trends associated with model angle of attack, and those associated with changes in the nozzle pressure ratio (NPR) of the AFC system.

Common Research Model↗
NASA NTRS1988

Convective flows in enclosures with vertical temperature or concentration gradients

The transport process in the fluid phase during the growth of a crystal has a profound influence on the structure and quality of the solid phase. In vertical growth techniques the fluid phase is often subjected to vertical temperature and concentration gradients. The main objective is to obtain more experimental data on convective flows in enclosures with vertical temperature or concentration gradients. Among actual crystal systems the parameters vary widely. The parametric ranges studied for mass transfer are mainly dictated by the electrochemical system employed to impose concentration gradients. Temperature or concentration difference are maintained between two horizontal end walls. The other walls are kept insulated. Experimental measurements and observations were made of the heat transfer or mass transfer, flow patterns, and the mean and fluctuating temperature distribution. The method used to visualize the flow pattern in the thermal cases is an electrochemical pH-indicator method. Laser shadowgraphs are employed to visualize flow patterns in the solutal cases.

Wang, L. W.↗
NASA NTRS1989

Convective flows in enclosures with vertical temperature or concentration gradients

The transport process in the fluid phase during the growth of a crystal has a profound influence on the structure and quality of the solid phase. In vertical growth techniques the fluid phase is often subjected to vertical temperature and concentration gradients. The main objective is to obtain more experimental data on convective flows in enclosures with vertical temperature or concentration gradients. Among actual crystal systems the parameters vary widely. The parametric ranges studied for mass transfer are mainly dictated by the electrochemical system employed to impose concentration gradients. Temperature or concentration difference are maintained between two horizontal end walls. The other walls are kept insulated. Experimental measurements and observations were made of the heat transfer or mass transfer, flow patterns, and the mean and fluctuating temperature distribution. The method used to visualize the flow pattern in the thermal cases is an electrochemical pH-indicator method. Laser shadowgraphs are employed to visualize flow patterns in the solutal cases.

Wang, L. W.↗
NASA NTRS2015

In-Flight Calibration Processes for the MMS Fluxgate Magnetometers

The calibration effort for the Magnetospheric Multiscale Mission (MMS) Analog Fluxgate (AFG) and DigitalFluxgate (DFG) magnetometers is a coordinated effort between three primary institutions: University of California, LosAngeles (UCLA); Space Research Institute, Graz, Austria (IWF); and Goddard Space Flight Center (GSFC). Since thesuccessful deployment of all 8 magnetometers on 17 March 2015, the effort to confirm and update the groundcalibrations has been underway during the MMS commissioning phase. The in-flight calibration processes evaluatetwelve parameters that determine the alignment, orthogonalization, offsets, and gains for all 8 magnetometers usingalgorithms originally developed by UCLA and the Technical University of Braunschweig and tailored to MMS by IWF,UCLA, and GSFC. We focus on the processes run at GSFC to determine the eight parameters associated with spin tonesand harmonics. We will also discuss the processing flow and interchange of parameters between GSFC, IWF, and UCLA.IWF determines the low range spin axis offsets using the Electron Drift Instrument (EDI). UCLA determines the absolutegains and sensor azimuth orientation using Earth field comparisons. We evaluate the performance achieved for MMS andgive examples of the quality of the resulting calibrations.

Electromagnetic field Measurements↗
NASA NTRS1974

Ultrasonic filtration of industrial chemical solutions

The practical results obtained as a result of filtering industrial chemical solutions under continuous flow conditions with the aid of an ultrasonic filter are presented. The main part of the assembly consists of an ultrasonic generator with an output power of about 400 W and the filtration assembly, in which there is a magnetostrictive amplifier constructed for 20.5 kHz. In addition to ensuring a continuous flow of filtered solution, ultrasonic filters can be replaced or cleaned at intervals of time that are 8-10 times greater than in the case of mechanical filters. They yield considerably better results as far as the size of the filtered particles is concerned. The parameters on which filtration quality depends are also presented.

Cosma, T.↗
NASA NTRS1978

Automatic Welding of Stainless Steel Tubing

To determine if the use of automatic welding would allow reduction of the radiographic inspection requirement, and thereby reduce fabrication costs, a series of welding tests were performed. In these tests an automatic welder was used on stainless steel tubing of 1/2, 3/4, and 1/2 inch diameter size. The optimum parameters were investigated to determine how much variation from optimum in machine settings could be tolerate and still result in a good quality weld. The process variables studied were the welding amperes, the revolutions per minute as a function of the circumferential weld travel speed, and the shielding gas flow. The investigation showed that the close control of process variables in conjunction with a thorough visual inspection of welds can be relied upon as an acceptable quality assurance procedure, thus permitting the radiographic inspection to be reduced by a large percentage when using the automatic process.

Clautice, W. E.↗
NASA NTRS2006

Aerosol-Assisted Chemical Vapor Deposited Thin Films for Space Photovoltaics

Copper indium disulfide thin films were deposited via aerosol-assisted chemical vapor deposition using single source precursors. Processing and post-processing parameters were varied in order to modify morphology, stoichiometry, crystallography, electrical properties, and optical properties in order to optimize device-quality material. Growth at atmospheric pressure in a horizontal hot-wall reactor at 395 C yielded best device films. Placing the susceptor closer to the evaporation zone and flowing a more precursor-rich carrier gas through the reactor yielded shinier, smoother, denser-looking films. Growth of (112)-oriented films yielded more Cu-rich films with fewer secondary phases than growth of (204)/(220)-oriented films. Post-deposition sulfur-vapor annealing enhanced stoichiometry and crystallinity of the films. Photoluminescence studies revealed four major emission bands (1.45, 1.43, 1.37, and 1.32 eV) and a broad band associated with deep defects. The highest device efficiency for an aerosol-assisted chemical vapor deposited cell was 1.03 percent.

Hepp, Aloysius F.↗
NASA NTRS1990

Comparisons of a Three-Dimensional, Full Navier Stokes Computer Model with High Mach Number Combuster Test Data

Comparisons between scramjet combustor data and a three-dimensional full Navier-Stokes calculation have been made to verify and substantiate computational fluid dynamics (CFD) codes and application procedures. High Mach number scramjet combustor development will rely heavily on CFD applications to provide wind tunnel-equivalent data of quality sufficient to design, build and fly hypersonic aircraft. Therefore. detailed comparisons between CFD results and test data are imperative. An experimental case is presented, for which combustor wall static pressures were measured and flow-fieid interferograms were obtained. A computer model was done of the experiment, and counterpart parameters are compared with experiment. The experiment involved a subscale combustor designed and fabricated for the National Aero-Space Plane Program, and tested in the Calspan Corporation 96" hypersonic shock tunnel. The combustor inlet ramp was inclined at a 20 angle to the shock tunnel nozzle axis, and resulting combustor entrance flow conditions simulated freestream M=10. The combustor body and cowl walls were instrumented with static pressure transducers, and the combustor lateral walls contained windows through which flowfield holographic interferograms were obtained. The CFD calculation involved a three-dimensional time-averaged full Navier-Stokes code applied to the axial flow segment containing fuel injection and combustion. The full Navier-Stokes approach allowed for mixed supersonic and subsonic flow, downstream-upstream communication in subsonic flow regions, and effects of adverse pressure gradients. The code included hydrogen-air chemistry in the combustor segment which begins near fuel injection and continues through combustor exhaust. Combustor ramp and inlet segments on the combustor lateral centerline were modelled as two dimensional. Comparisons to be shown include calculated versus measured wall static pressures as functions of axial flow coordinate, and calculated path-averaged density contours versus an holographic Interferogram.

Watkins, William B.↗