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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 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

EPE The Extreme Physics Explorer

The Extreme Physics Explorer (EPE) is a mission concept that will address fundamental and timely questions in astrophysics which are primary science objectives of IXO. The reach of EPE to the areas outlined in NASA RFI NNH11ZDA018L is shown as a table. The dark green indicates areas in which EPE can do the basic IXO science, and the light green areas where EPE can contribute but will not reach the full IXO capability. To address these science questions, EPE will trace orbits close to the event horizon of black holes, measure black hole spin in active galactic nuclei (AGN), use spectroscopy to characterize outflows and the environment of AGN, map bulk motions and turbulence in galaxy clusters, and observe the process of cosmic feedback where black holes inject energy on galactic and intergalactic scales. EPE gives up the high resolution imaging of IXO in return for lightweight, high TRL foil mirrors which will provide >20 times the effective area of ASTRO-H and similar spatial resolution, with a beam sufficient to study point sources and nearby galaxies and clusters. Advances in micro-calorimeters allow improved performance at high rates with twice the energy resolution of ASTRO-H. A lower TRL option would provide 200 times the area of ASTRO-H using a micro-channel plate optic (MCPO) and a deployable optical bench. Both options are in the middle range of RFI missions at between $600M and $1000M. The EPE foil optic has direct heritage to ASTRO-H, allowing robust cost estimates. The spacecraft is entirely off the shelf and introduces no difficult requirements. The mission could be started and launched in this decade to an L2 orbit, with a three-year lifetime and consumables for 5 years. While ASTRO-H will give us the first taste of high-resolution, non-dispersive X-ray spectroscopy, it will be limited to small numbers of objects in many categories. EPE will give us the first statistically significant samples in each of these categories.

Garcia, Michael↗
NASA NTRS1995

Application of Pressure Sensitive Paint in Hypersonic Flows

It is well known in the aerodynamic field that pressure distribution measurement over the surface of an aircraft model is a problem in experimental aerodynamics. For one thing, a continuous pressure map can not be obtained with the current experimental methods since they are discrete. Therefore, interpolation or CFD methods must be used for a more complete picture of the phenomenon under study. For this study, a new technique was investigated which would provide a continuous pressure distribution over the surface under consideration. The new method is pressure sensitive paint. When pressure sensitive paint is applied to an aerodynamic surface and placed in an operating wind-tunnel under appropriate lighting, the molecules luminesce as a function of the local pressure of oxygen over the surface of interest during aerodynamic flow. The resulting image will be brightest in the areas of low pressure (low oxygen concentration), and less intense in the areas of high pressure (where oxygen is most abundant on the surface). The objective of this investigation was to use pressure sensitive paint samples from McDonnell Douglas (MDD) for calibration purpose in order to assess the response of the paint under appropriate lighting and to use the samples over a flat plate/conical fin mounted at 75 degrees from the center of the plate in order to study the shock/boundary layer interaction at Mach 6 in the Von Karman wind-tunnel. From the result obtained it was concluded that temperature significantly affects the response of the paint and should be given the uppermost attention in the case of hypersonic flows. Also, it was found that past a certain temperature threshold, the paint intensity degradation became irreversible. The comparison between the pressure tap measurement and the pressure sensitive paint showed the right trend. However, there exists a shift when it comes to the actual value. Therefore, further investigation is under way to find the cause of the shift.

Jules, Kenol↗
NASA NTRS1994

Study of noise on a small-scale hovering tilt rotor

A study of the noise from a small-scale, semi-span test of a hovering tilt rotor is presented. The effect on noise of the tilt rotor fountain and of several tilt rotor configuration changes is examined. Measurments were made of an isolated rotor; rotor and wing; rotor and image plane; and rotor, wing and image plane. This last configuration models a tilt rotor. With a tilt rotor, the wing turns some of the rotor downwash inboard. When the flows meet, some of the flow is forced upward creating a fountain. Some of the fountain is ingested into the rotor disc. Rotor fountain interactions produce very unsteady impulsive noise to the rear of the aircraft. Configuration changes to investigate download reduction included increasing the rotor/wing separation, deflecting the flap, adding the nacelle, adding vortex trapping plates and blowing on the upper surface. These configuration changes produced little or no effect on the noise, although they changed the net download. Increasing the wing span, however, reduced the annoying content of this impulse noise about 2dB.

Mosher, Marianne↗
NASA NTRS2018

Remote Sensing of Venusian Seismic Activity with a Small Spacecraft, the VAMOS Mission Concept

The Venusian atmosphere creates inhospitable temperature and pressure conditions for the surface of Venus, Earth’s twin planet, making in-situ measurements of any appreciable length difficult, expensive, and risky to obtain. Yet, because of the apparent youthfulness of Venus’ surface features, long-duration seismic observations are in high demand in order to determine and understand the dynamic processes taking place in lieu of plate tectonics. The Venus Airglow Measurements and Orbiter for Seismicity (VAMOS) mission concept would make use of the dense Venusian atmosphere as a medium to conduct seismic vibrations from the surface to the ionosphere. Here, the resulting atmospheric gravity waves and acoustic waves can be observed in the form of perturbations in airglow emissions, the basic principles for which have been demonstrated at Earth following a tsunami and at Venus with the European Venus Express’s Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument. In addition, these observations would enable VAMOS to determine the crustal structure and ionospheric variability of Venus without approaching the surface or atmosphere themselves. Equipped with an instrument of modest size and mass, the baseline VAMOS spacecraft is designed to fit within a SmallSat form factor and travel to Venus predominantly under its own power. VAMOS would enter into an orbit uniquely suited for the longduration, full-disk staring observations required for seismic readings. VAMOS’ journey would be enabled by modern solar electric propulsion technology and SmallSat avionics, which allow the spacecraft to reach Venus and autonomously filter observation data on board to detect Venus-quake events. Currently, trade studies are being conducted to determine mission architecture robustness to launch and rideshare opportunities. Key spacecraft challenges for VAMOS, just as with many SmallSat-based mission concepts, include thermal and power management, onboard processing capabilities, telecommunications throughput, and propulsion technology. The VAMOS mission concept is being studied at JPL as part of the NASA Planetary Science Deep Space SmallSat Studies (PSDS3) program, which will not only produce a viable and exciting mission concept for a Venus SmallSat, but will have the opportunity to examine many issues facing the development of SmallSats for planetary exploration. These include SmallSat solar electric propulsion, autonomy, telecommunications, and resource management that can be applied to various inner solar system mission architectures.

Helbert, Jörn↗
DOE OSTI2024

Shock tube experiments on the three-layer Richtmyer–Meshkov instability

Here, a vertical shock tube is used for experiments on the three-layer Richtmyer–Meshkov instability. Two closely spaced membrane-less interfaces are formed by the flow of two different sects of three gases: one with air above CO 2 above SF 6 and the other with helium above air above SF 6 . The lightest of the three gases enters the shock tube at the top of the driven section and flows downward. Conversely, the heaviest gas enters at the bottom of the shock tube and flows upward while the intermediate density gas enters at the middle through porous plates. All three gases are allowed to escape through holes at the layer location, leaving an approximately 30-mm layer of intermediate-density gas suspended between the lightest gas from above and the heaviest gas from below. A single-mode, two-dimensional initial perturbation is then imposed on the lower interface by oscillating the shock tube in the horizontal direction. The flow is visualized by seeding the intermediate gas with particles and illuminating it with a pulsed laser. Image sequences are then captured using high-speed video cameras. Perturbation amplitude measurements are made from the three-layer system and compared with measurements from 2, two-layer systems. It is observed that the presence of the upper, initially flat interface produces a decrease in growth of instability amplitude in the nonlinear phase over an equivalent single-interface configuration.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1972

Pulsed differential holographic measurements of vibration modes of high temperature panels

Holography is a lensless imaging technique which can be applied to measure static or dynamic displacements of structures. Conventional holography cannot be readily applied to measure vibration modes of high-temperature structures, due to difficulties caused by thermal convection currents. The present report discusses the use of pulsed differential holography, which is a technique for recording structural motions in the presence of random fluctuations such as turbulence. An analysis of the differential method is presented, and demonstration experiments were conducted using heated stainless steel plates. Vibration modes were successfully recorded for the heated plates at temperatures of 1000, 1600, and 2000 F. The technique appears promising for such future measurments as vibrations of the space shuttle TPS panels or recording flutter of aeroelastic models in a wind-tunnel.

Evensen, D. A.↗
NASA NTRS1988

Aerodynamic investigation by infrared imaging

Infrared imaging systems can be used to measure temperatures of actively heated bodies immersed in an airstream. This monitoring of the convective heat transfer process, provides also information about the interaction between the body and the flow. The concept appeals to Nusselt/Reynolds numbers relations in order to produce data of interest from surface temperatures. Two test cases are presented and reference is made to analytical results: the mapping of a laminar jet and the temperature distribution along a constant power heated flat plate in laminar boundary layer regime. Although this research is currently focused on low speed aerodynamics, the extension to high speed aerodynamics, where the body undergoes frictional heating is of interest in this context, too.

Roberts, A. Sidney, Jr.↗
NASA NTRS1997

High-Flux, High-Temperature Thermal Vacuum Qualification Testing of a Solar Receiver Aperture Shield

As part of the International Space Station (ISS) Phase 1 program, NASA Lewis Research Center (LERC) and the Russian Space Agency (RSA) teamed together to design, build and flight test the world's first orbital Solar Dynamic Power System (SDPS) on the Russian space station Mir. The Solar Dynamic Flight Demonstration (SDFD) program was to operate a nominal 2 kWe SDPS on Mir for a period up to 1-year starting in late 1997. Unfortunately, the SDFD mission was demanifested from the ISS phase 1 shuttle program in early 1996. However, substantial flight hardware and prototypical flight hardware was built including a heat receiver and aperture shield. The aperture shield comprises the front face of the cylindrical cavity heat receiver and is located at the focal plane of the solar concentrator. It is constructed of a stainless steel plate with a 1-m outside diameter, a 0.24-m inside diameter and covered with high-temperature, refractory metal Multi-Foil Insulation (MFI). The aperture shield must minimize heat loss from the receiver cavity, provide a stiff, high strength structure to accommodate shuttle launch loads and protect receiver structures from highly concentrated solar fluxes during concentrator off-pointing events. To satisfy Mir operational safety protocols, the aperture shield was required to accommodate direct impingement of the intensely concentrated solar image for a 1-hour period. To verify thermal-structural durability under the anticipated high-flux, high-temperature loading, an aperture shield test article was constructed and underwent a series of two tests in a large thermal vacuum chamber configured with a reflective, point-focus solar concentrator and a solar simulator. The test article was positioned near the focal plane and exposed to concentrated solar flux for a period of 1-hour. In the first test, a near equilibrium temperature of 1862 K was attained in the center of the shield hot spot. In the second test, with increased incident flux, a near equilibrium temperature of 2072 K was achieved. The aperture shield sustained no visible damage as a result of the exposures. This paper describes the aperture shield thermal-vacuum qualification test program including the test article, test facility, procedures, data collection, test success criteria, results and conclusions.

Kerslake, Thomas W.↗
NASA NTRS2000

Thermal Field Imaging Using Ultrasound

It is often desirable to be able to determine the temperature field in the interiors of opaque fluids forced into convection by externally imposed temperature gradients. To measure the temperature at a point in an opaque fluid in the usual fashion requires insertion of a probe, and to determine the full field therefore requires either the ability to move this probe or the introduction of multiple probes. Neither of these solutions is particularly satisfactory, although they can lead to quite accurate measurements. As an alternative we have investigated the use of ultrasound as a relatively non-intrusive probe of the temperature field in convecting opaque fluids. The temperature dependence of the sound velocity can be sufficiently great to permit a determination of the temperature from timing the traversal of an ultrasound pulse across a chamber. In this paper we will present our results on convecting flows of transparent and opaque fluids. Our experimental cells consist of relatively narrow rectangular cavities made of thermally insulating materials on the sides, and metal top and bottom plates. The ultrasound transducer is powered by a pulser/receiver, the signal output of which goes to a very high speed signal averager. The average of several hundred to several thousand signals is then sent to a computer for storage and analysis. The experimental procedure is to establish a convective flow by imposing a vertical temperature gradient on the chamber, and then to measure, at several regularly spaced locations, the transit time for an ultrasound pulse to traverse the chamber horizontally (parallel to the convecting rolls) and return to the transducer. The transit time is related to the temperature of the fluid through which the sound pulse travels. Knowing the relationship between transit time and temperature (determined in a separate experiment), we can extract the average temperature across the chamber at that location. By changing the location of the transducer it is then possible to find the average temperature at different locations along the chamber, thereby determining the temperature profile along the system. (In the future we will construct an array of transducers. This will give us the capability to determine the temperature profile much more rapidly than at present, an important consideration if time-dependent phenomena are to be studied.) To validate our procedure we introduced encapsulated liquid crystal particles into glycerol. The liquid crystal particles' color varies depending on the temperature of the fluid. A photograph of the fluid through transparent sidewalls therefore gives a picture of the temperature field of the convecting fluid, independent of our ultrasound imaging. A representative result is shown in the Figure 1, which reveals a very satisfying correspondence between the two techniques. Therefore we have a great deal of confidence that the ultrasound imaging approach is indeed measuring the actual temperature profile of the fluid. The technique has also been applied to convecting liquid metal flows, and representative data will be presented from those experiments as well.

Andereck, D.↗
NASA NTRS1982

Low intensity X-ray and gamma-ray spectrometer

A low intensity X-ray and gamma ray spectrometer for imaging, counting, and energy resolving of single invisible radiation particles is described. The spectrometer includes a converting device for converting single invisible radiation particles to visible light photons. Another converting device converts the visible light photons to photoelectrons. A fiber optics coupling device couples together the two converting devices. An intensifying device intensifies the photoelectrons by an average gain factor of between 10 to the 4th power and 10 to the 7th power. The tensifying device is an anti-ion feedback microchannel plate amplifier which is operated substantially below saturation. A displaying device displays the intensified photoelectrons. The displaying device 32 indicates the spatial position, number, and energy of the incoming single invisible radiation particles.

Yin, L. I.↗
NASA NTRS1994

The optical and near-infrared colors of galaxies, 1: The photometric data

We present optical and near-infrared photometry and spectroscopic redshifts of a well defined sample of 171 field galaxies selected from three high galactic latitude fields. This data set forms the basis for subsequent studies to characterize the trends, dispersion, and evolution of rest-frame colors and image structure. A subset of 143 galaxies constitutes a magnitude-limited sample to B approx. 19.9-20.75 (depending on field), with a median redshift of 0.14, and a maximum redshift of 0.54. This subset is statistically representative in its sampling of the apparent color distribution of galaxies. Thirty six galaxies were selected to have the reddest red-optical colors in two redshift intervals between 0.2 less than z less than 0.3. Photometric passbands are similar to U, B, V, I, and K, and sample galaxy spectral energy distributions between 0.37 and 2.2 micrometers in the observed frame, or down to 0.26 micrometers in the rest frame for the most distant galaxies. B and K images of the entire sample are assembled to form the first optical and near-infrared atlas of a statistically-representative sample of field galaxies. We discuss techniques for faint field-galaxy photometry, including a working definition of a total magnitude, and a method for matching magnitudes in different passbands and different seeing conditions to ensure reliable, integrated colors. Photographic saturation, which substantially affects the brightest 12% of our sample in the optical bands, is corrected with a model employing measured plate-density distributions for each galaxy, calibrated via similar measurements for stars as a function of known saturation level. Both the relative and absolute calibration of our photometry are demonstrated.

Bershady, Matthew A.↗
NASA NTRS2010

Validation of Supersonic Film Cooling Modeling for Liquid Rocket Engine Applications

Topics include: upper stage engine key requirements and design drivers; Calspan "stage 1" results, He slot injection into hypersonic flow (air); test articles for shock generator diagram, slot injector details, and instrumentation positions; test conditions; modeling approach; 2-d grid used for film cooling simulations of test article; heat flux profiles from 2-d flat plate simulations (run #4); heat flux profiles from 2-d backward facing step simulations (run #43); isometric sketch of single coolant nozzle, and x-z grid of half-nozzle domain; comparison of 2-d and 3-d simulations of coolant nozzles (run #45); flowfield properties along coolant nozzle centerline (run #45); comparison of 3-d CFD nozzle flow calculations with experimental data; nozzle exit plane reduced to linear profile for use in 2-d film-cooling simulations (run #45); synthetic Schlieren image of coolant injection region (run #45); axial velocity profiles from 2-d film-cooling simulation (run #45); coolant mass fraction profiles from 2-d film-cooling simulation (run #45); heat flux profiles from 2-d film cooling simulations (run #45); heat flux profiles from 2-d film cooling simulations (runs #47, #45, and #47); 3-d grid used for film cooling simulations of test article; heat flux contours from 3-d film-cooling simulation (run #45); and heat flux profiles from 3-d and 2-d film cooling simulations (runs #44, #46, and #47).

Morris, Christopher I.↗
NASA NTRS2012

Direct Imaging of Extra-Solar Planets in Star Forming Regions: Lessons Learned from a False Positive Around IM Lup

Context. Most exoplanet imagers consist of ground-based adaptive optics coronagraphic cameras which are currently limited in contrast, sensitivity and astrometric precision, but advantageously observe in the near-infrared window (1 5 m). Because of these practical limitations, our current observational aim at detecting and characterizing planets puts heavy constraints on target selection, observing strategies, data reduction, and follow-up. Most surveys so far have thus targeted young systems (1 100 Myr) to catch the putative remnant thermal radiation of giant planets, which peaks in the near-infrared. They also favor systems in the solar neighborhood (d less than 80 pc), which eases angular resolution requirements but also ensures a good knowledge of the distance and proper motion, which are critical to secure the planet status, and enable subsequent characterization. Aims. Because of their youth, it is very tempting to target the nearby star forming regions, which are typically twice as far as the bulk of objects usually combed for planets by direct imaging. Probing these interesting reservoirs sets additional constraints that we review in this paper by presenting the planet search that we initiated in 2008 around the disk-bearing T Tauri star IM Lup, which is part of the Lupus star forming region (140-190 pc). Methods. We show and discuss why age determination, the choice of evolutionary model for both the central star and the planet, precise knowledge of the host star proper motion, relative or absolute (between different instruments) astrometric accuracy (including plate scale calibration), and patience are the key ingredients for exoplanet searches around more distant young stars. Results. Unfortunately, most of the time, precision and perseverance are not paying off: we discovered a candidate companion around IM Lup in 2008, which we report here to be an unbound background object. We nevertheless review in details the lessons learned from our endeavor, and additionally present the best detection limits ever calculated for IM Lup. We also accessorily report on the successful use of innovative data reduction techniques, such as the damped-LOCI and iterative roll subtraction.

D Mawet↗
NASA NTRS2023

Turbulence Model Validation Through Joint Experimental /Computational Studies of Separated Flow Over A Three-Dimensional Tapered Bump: Part I - Experimental Investigation

The results of a three-year experimental campaign aimed at comprehensively documenting the separated flow over a three-dimensional bump are presented with the purpose of generating a benchmark experimental database useful in validating computational fluid dynamics (CFD) flow simulations. The bump model geometry was designed to provide well-defined and repeatable smooth-body flow separation conditions that were suitable for both experiments and simulations. The bump had a Gaussian streamwise profile with a constant height equal to 8.5% of its width over the central 60% of the test section width. The remaining 40% were outboard spanwise portions that gradually taper to zero using an error function profile to minimize side-wall boundary layer effects. The model was immersed in a turbulent boundary layer that was developed on a suspended flat plate in the Notre Dame Mach 0.6 Wind Tunnel. In order to document the effect of the incoming boundary layer thickness on the flow separation, the bump model could be located at two streamwise positions. The mean velocity and turbulence intensity of the wind tunnel freestream flow field and approaching turbulent boundary layer were fully documented. The measurements of the flow separation region included surface visualization, wall shear stress using oil-film interferometry, mean and dynamic surface pressure, and planar and stereoscopic particle image velocimetry. The experiments were conducted over a range of Mach numbers from 0.05 to 0.2 corresponding to a range of Reynolds numbers based on the test section spanwise dimension (0.914m) of 1.0 × 10 6 ≤ Re L = U ∞ L/ν ≤ 4.0 × 10 6 . The bulk of the results are presented for the higher Mach number conditions of 0.1 and 0.2 with Re L = 2.0 × 10 6 and 4.0 × 10 6 , respectively. Extensive uncertainty analysis of the data was performed. The data is archived in the NASA Langley Turbulence Modeling Resource website at https://turbmodels.larc.nasa.gov/Other_exp_Data/speedbump_sep_exp.html. In addition to the experiments, a computational effort was made in parallel by the CFD group at Boeing Research & Technology highlighting the usefulness of the data set, which is outlined in the accompanying CFD report.

Flow separation↗
NASA NTRS2003

Flow-Tagging Velocimetry for Hypersonic Flows Using Fluorescence of Nitric Oxide

We demonstrate a new variation of molecular-tagging velocimetry for hypersonic flows based on laser-induced fluorescence. A thin line of nitric-oxide molecules is excited with a laser beam and then, after a time delay, a fluorescence image of the displaced line is acquired. One component of velocity is determined from the time of flight. This method is applied to measure the velocity profile in a Mach 8.5 laminar, hypersonic boundary layer in the Australian National University s T2 free-piston shock tunnel. The single-shot velocity measurement uncertainty in the freestream was found to be 3.5%, based on 90% confidence. The method is also demonstrated in the separated flow region forward of a blunt fin attached to a flat plate in a Mach 7.4 flow produced by the Australian National University s T3 free-piston shock tunnel. The measurement uncertainty in the blunt fin experiment is approximately 30%, owing mainly to low fluorescence intensities, which could be improved significantly in future experiments. This velocimetry method is applicable to very high-speed flows that have low collisional quenching of the fluorescing species. It is particularly convenient in facilities where planar laser-induced fluorescence is already being performed.

Danehy, Paul M.↗
NASA NTRS2019

Thermal design and on-orbit performance of the ECOSTRESS instrument

The ECOSystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) instrument, launched on June 29, 2018, has completed nine months of operation in space. ECOSTRESS is a multispectral thermal infrared imaging radiometer and its primary mission is to investigate and understand how climate change affects water and carbon usage on Earth. The thermal control subsystem consists of a combination of active and passive components to maintain instrument components within the allowable flight temperature limits. Its focal plane detector is cooled to 65K by a pair of mechanical cryocoolers and a third mechanical cryocooler cools an intermediate cold shield to 130K. The heat dissipation generated by cryocoolers and electronics, is removed through non-planar cold plates and tube-on plate heat exchanger, which are cooled by a circulating fluid -EF module. The heat collected by the JEM-EF fluid is exchanged with a fluid loop that circulates through radiators located on the exterior of the Space Station. This paper provides an overview of the thermal and cryogenic system design, thermal analysis results and reviews the on-orbit thermal performance.

Romero, M.↗
NASA NTRS2006

Kalman Filter for Calibrating a Telescope Focal Plane

The instrument-pointing frame (IPF) Kalman filter, and an algorithm that implements this filter, have been devised for calibrating the focal plane of a telescope. As used here, calibration signifies, more specifically, a combination of measurements and calculations directed toward ensuring accuracy in aiming the telescope and determining the locations of objects imaged in various arrays of photodetectors in instruments located on the focal plane. The IPF Kalman filter was originally intended for application to a spaceborne infrared astronomical telescope, but can also be applied to other spaceborne and ground-based telescopes. In the traditional approach to calibration of a telescope, (1) one team of experts concentrates on estimating parameters (e.g., pointing alignments and gyroscope drifts) that are classified as being of primarily an engineering nature, (2) another team of experts concentrates on estimating calibration parameters (e.g., plate scales and optical distortions) that are classified as being primarily of a scientific nature, and (3) the two teams repeatedly exchange data in an iterative process in which each team refines its estimates with the help of the data provided by the other team. This iterative process is inefficient and uneconomical because it is time-consuming and entails the maintenance of two survey teams and the development of computer programs specific to the requirements of each team. Moreover, theoretical analysis reveals that the engineering/ science iterative approach is not optimal in that it does not yield the best estimates of focal-plane parameters and, depending on the application, may not even enable convergence toward a set of estimates.

Kang, Bryan↗