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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,261 records · Page 70
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Temperature Mapping of Air Film-Cooled Thermal Barrier Coated Surfaces Using Phosphor Thermometry

While the effects of thermal barrier coating (TBC) thermal protection and air film cooling effectiveness for jet engine components are usually studied separately, their contributions to combined cooling effectiveness are interdependent and are not simply additive. Therefore, combined cooling effectiveness must be measured to achieve an optimum balance between TBC thermal protection and air film cooling. Phosphor thermometry offers several advantages for mapping temperatures of air film cooled surfaces. While infrared thermography has been typically applied to study air film cooling effectiveness, temperature accuracy depends on knowing surface emissivity (which may change) and correcting for effects of reflected radiation. Because decay time-based full-field phosphor thermometry is relatively immune to these effects, it can be applied advantageously to temperature mapping of air film-cooled TBC-coated surfaces. In this presentation, an overview will be given of efforts at NASA Glenn Research Center to perform temperature mapping of air film-cooled TBC-coated surfaces in a burner rig test environment. The effects of thermal background radiation and flame chemiluminescence on the measurements are investigated, and the strengths and limitations of this method for studying air film cooling effectiveness are discussed.

air film cooling↗
DOE OSTI2016

Effects of irradiation distance on supply of reactive oxygen species to the bottom of a Petri dish filled with liquid by an atmospheric O{sub 2}/He plasma jet

The impact of irradiation distances on plasma jet-induced specific effects on the supply of reactive oxygen species (ROS) to the bottom of a Petri dish filled with liquid was investigated using a KI-starch gel reagent that can be employed as a ROS indicator even in water. O{sub 3} exposure experiments without plasma irradiation were also performed to elucidate the specific effects of the plasma jet. Relative concentrations of ROS transported to the bottom were evaluated using absorbance measurements. The results indicated that ROS supply to the bottom is markedly enhanced by the plasma jet irradiation at shorter irradiation distances, whereas similar results could not be obtained for the O{sub 3} exposure. In these cases, the liquid mixing in the depth direction was also enhanced by the plasma jet irradiation only, and the supply of reactive atomic oxygen to the liquid surface was markedly increased as well.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1982

The evolution of the mesoscale environment of severe local storms Preliminary modeling results

A mesoscale model is employed for predicting two severe weather events observed during thy 1979 SESAME field programs. Particular attention is given to the development and decay of a low-level jet, to the formation of a mesoscale convective complex (MCC) and its modification of lower- and upper-level circulation, to the formation of mesoscale regions of heavy precipitation, the intensification of surface warm and cold fronts, the formation of drylines, dynamic coupling of upper- and low-level jets, the formation of a mountain wave, and the formation and maintenance of capping inversions. A summary of the physics and parameters of a tornado outbreak and a heavy precipitation event are given for a simple bulk-PBL formulation with no heating. A ten-layer model was demonstrated to be sufficient for generating and maintaining distinct vertical gradients of temperature, moisture, and wind across low-level inversions.

Anthes, R. A.↗
NASA NTRS1989

Arc jet diagnostics tests

Two objectives were addressed during a 10 week 1988 NASA/ASEE summer faculty fellowship at the Johnson Space Center Atmospheric Reentry Materials Structures Evaluation Facility (ARMSEF). These objectives were the evaluation of mass spectrometry for the measurement of atomic and molecular species in an arc jet environment, and the determination of atomic recombination coefficients for reaction cured glass (RCG) coated high temperature surface insulation (HRSI) materials subjected to simulated reentry conditions. Evaluation of mass spectrometry for the measurement of atomic and molecular species provided some of the first measurements of point compositions in arc jet tunnel environments. A major objective of this project centered around the sampling residence time. A three staged vacuum sampling system pulled the molecules and atoms from the arc jet to a quadrupole ionization mass spectrometer in 400 milliseconds. Conditions investigated included a composition survey across the nozzle exit at 3 cm z-distance from the nozzle exit for 3 different currents. Also, a point composition survey was taken around a shock created by the presence of a blunt body.

Willey, Ronald J.↗
NASA NTRSDate not supplied

Flow Physics Study of Sweeping Jet Actuation on an NACA 0015 Swept Wing Configuration

Results from a recently completed active flow control (AFC) experiment on a low aspect ratio, AR = 4.35, 30 degree swept, semispan wing with a 30% chord trailing edge flap are presented. The constant chord NACA 0015 wing is configured with sweeping jet actuators at the flap shoulder to facilitate our study of three-dimensional, swept wing separated and AFC controlled flowfields on the flap. Two flap deflection angles (delta_f = 0 degrees and 20 degrees) are examined. Oil and tuft flow visualization data, steady and unsteady pressure data, and particle image velocimetry (PIV) complement the balance lift and drag data. These results are used to examine smooth body separation, fixed separation, and the AFC-controlled flap flowfield downstream of a sweeping jet actuator. A momentum coefficient of 1.1% reattaches the flow to the flap surface when flap delta_f = 20 degrees increasing lift by approximately 0.26. This fundamental study is a first step in a research effort focused on improving the efficiency of AFC systems for swept wing applications.

active flow control↗
DOE OSTI2025

VitriEdge: Repairable & Durable Vitrimer Coatings for Wind Turbine Blade Leading Edges

The primary goal of this Level 1b incubator project was to explore the use of vitrimer coatings for repair of leading-edge erosion on end-of-life wind turbine blade surfaces, beyond coating strength of adhesion which has previously been demonstrated in the Level 1a project. Uniform vitrimer coatings (thickness: 400 µm) were applied to two end-of-life wind turbine blades for flexural, fatigue, and laminate tensile testing where the addition of the coating did not produce any statistical variation in tensile properties with minor drops in flexural strength for some laminate formulations. However, a <2% variation in storage modulus was measured for laminate structures (i.e., blade samples with vitrimer coatings) across 100,000 flexural cycles and upon laminate tensile failure, the vitrimer coatings displayed no visible signs of delamination. In addition, three methods to heal vitrimer coating damage was displayed: oven heating, addition of hot water, and a forced convection heat gun. All three heating and healing mechanisms demonstrated significant healing with scratch depths decreasing between 79-91% at healing times ranging between 1-min and 10-minutes. Finally, a water jet machine was used to simulate rain erosion for both the blade surfaces and vitrimer-coated blade surfaces where the diameter and depth of the damage was recorded as a function of exposure time, water pressure, height of exposure, and angle of exposure. Of interest, while the vitrimer coating did not significantly lessen the damage experienced during rain erosion, the addition of vitrimer composite coatings(5 wt.% mica addition) did result in a crack-resistant, durable coating capable of self-healing behavior and in all cases the angle of rain exposure was the most critical parameter explored. It is crucial to continue exploring this space where vitrimer coatings are of interest for both their self-healing properties and potential use as reversible adhesives.

17 WIND ENERGY↗
NASA NTRS1997

An Experimental Study of the Near Field Region of a Free Jet with Passive Mixing Tabs

An experimental study was performed to determine the flow characteristics of a tabbed free jet. Results were acquired in the near field (nominally 2 tab widths upstream to 2 tab widths downstream of the exit plane) of a tabbed jet. Upstream pressure results showed static pressure distributions in both the x-and y-directions along the top surface of the tunnel. Hot-wire measurements showed rapid expansion of the core fluid into the ambient region. Two counter rotating regions of streamwise vorticity were shown on each side of the primary tab. An enhancement of the tabbed jet concept was proposed and tested. Specifically, two tabs, half the scale of the primary tab, were added to the primary tab to provide attachment surfaces for the normally occurring ejection of fluid. The secondary tabs caused a slight increase in the streamwise vorticity created from the upstream static pressure gradient while significantly increasing the re-oriented boundary layer vorticity. The combined pumping effect of the two counter rotating regions of vorticity caused a significant increase in the transport of the jet core fluid into the surrounding region.

Bohl, D. G.↗
DOE OSTI2023

Potential Non-Linearities in the High Latitude Circulation and Ozone Response to Stratospheric Aerosol Injection

The impacts of Stratospheric Aerosol Injection (SAI) on the atmosphere and surface climate depend on when and where the sulfate aerosol precursors are injected, as well as on how much surface cooling is to be achieved. We use a set of CESM2(WACCM6) SAI simulations achieving three different levels of global mean surface cooling and demonstrate that unlike some direct surface climate impacts driven by the reflection of solar radiation by sulfate aerosols, the SAI-induced changes in the high latitude circulation and ozone are more complex and could be non-linear. This manifests in our simulations by disproportionally larger Antarctic springtime ozone loss, significantly larger intra-ensemble spread of the Arctic stratospheric jet and ozone responses, and non-linear impacts on the extratropical modes of surface climate variability under the strongest-cooling SAI scenario compared to the weakest one. These potential non-linearities may add to uncertainties in projections of regional surface impacts under SAI.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1974

An experimental and analytical study of slip and catalytic boundary conditions applied to spheres in low Reynolds number arc jet flows

Measurements of low-density dissociated arc-heated flows around low and high surface catalycity spheres are compared with numerical solutions to the full Navier-Stokes equations for reacting gas flow fields, taking into account slip and finite surface catalytic boundary conditions. A time-dependent finite difference solution technique developed by Li (1973, 1974) is used in the investigation and a simple transport model is employed for the flows considered. The correctness of the solution approach is demonstrated by the very good agreement obtained between experimental and computational data.

Scott, C. D.↗
DOE OSTI2020

Experimental characterization of a section of a spherically imploding plasma liner formed by merging hypersonic plasma jets

In this work, we report experimental results on merging of hypersonic plasma jets, which is the fundamental building block for forming spherically imploding plasma liners as a potential standoff compression driver for magneto-inertial fusion. Jets are formed and launched by contoured-gap coaxial plasma guns mounted at the six vertices and the center of a hexagon covering approximately one-tenth of the surface area of a 9-ft-diameter spherical chamber. First, from experiments with two and three merging jets of four different species (N, Ar, Kr, and Xe), we show that (1) density spatial non-uniformities can be large (with electron-density jumps ranging from 2.9 for N to 6.6 for Xe) when shocks form upon jet merging, but smaller (density jumps <2) when shocks do not form; (2) jet impurities (20% Ti in these experiments) can increase the level of density spatial non-uniformity by increasing the collisionality of jet merging, leading to shock formation rather than potentially more desirable shockless jet merging; and (3) the liner Mach number can remain high (≳10), as required for plasma liners to be an effective compression driver. Secondly, from experiments with six and seven merging jets using Ar, we present results with improved jet-to-jet mass balance of <2% across jets, including (1) evidence of substantially increased balance in the jet merging and symmetry of the liner structure and (2) potentially favorable changes in the jet-merging morphology with the addition of the seventh jet. Ultimately, for both experiments, we present comparisons between experimental and synthetic data from three-dimensional hydrodynamic codes.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1993

Symmetry in polarimetric remote sensing

Relationships among polarimetric backscattering coefficients are derived from the viewpoint of symmetry groups. For both reciprocal and non-reciprocal media, symmetry encountered in remote sensing due to reflection, rotation, azimuthal, and centrical symmetry groups is considered. The derived properties are general and valid to all scattering mechanisms, including volume and surface scatterings and their interactions, in a given symmetrical configuration. The scattering coefficients calculated from theoretical models for layer random media and rough surfaces are shown to obey the symmetry relations. Use of symmetry properties in remote sensing of structural and environmental responses of scattering media is also discussed. Orientations of spheroidal scatterers described by spherical, uniform, planophile, plagiothile, erectophile, and extremophile distributions are considered to derive their polarimetric backscattering characteristics. These distributions can be identified from the observed scattering coefficients by comparison with theoretical symmetry calculations. A new parameter is then defined to study scattering structures in geophysical media. Observations from polarimetric data acquired by the Jet Propulsion Laboratory airborne synthetic aperture radar over forests, sea ice, and sea surface are presented. Experimental evidences of the symmetry relationships are shown and their use in polarimetric remote sensing is illustrated. For forests, the coniferous forest in Mt. Shasta area (California) and mixed forest near Presque Isle (Maine) exhibit characteristics of the centrical symmetry at C-band. For sea ice in the Beaufort Sea, multi-year sea ice has a cross-polarized ratio e close to e(sub 0), calculated from symmetry, due to the randomness in the scattering structure. First-year sea ice has e much smaller than e(sub 0) due to the preferential alignment of the columnar structure of the ice. From polarimetric data of a sea surface in the Bering Sea, it is observed that e and e(sub 0) are increasing with incident angle and e is greater than e(sub 0) at L-band because of the directional feature of sea surface waves. Symmetry properties of geophysical media can also be used to calibrate polarimetric radars.

Nghiem, S. V.↗
DOE OSTI2015

Trailing edge cooling using angled impingement on surface enhanced with cast chevron arrangements

A gas turbine engine component, including: a pressure side (12) having an interior surface (34); a suction side (14) having an interior surface (36); a trailing edge portion (30); and a plurality of suction side and pressure side impingement orifices (24) disposed in the trailing edge portion (30). Each suction side impingement orifice is configured to direct an impingement jet (48) at an acute angle (52) onto a target area (60) that encompasses a tip (140) of a chevron (122) within a chevron arrangement (120) formed in the suction side interior surface. Each pressure side impingement orifice is configured to direct an impingement jet at an acute angle onto an elongated target area that encompasses a tip of a chevron within a chevron arrangement formed in the pressure side interior surface.

17 WIND ENERGY↗
DOE OSTI2012

Fabrication of copper-based anodes via atmosphoric plasma spraying techniques

A fuel electrode anode (18) for a solid oxide fuel cell is made by presenting a solid oxide fuel cell having an electrolyte surface (15), mixing copper powder with solid oxide electrolyte in a mixing step (24, 44) to provide a spray feedstock (30,50) which is fed into a plasma jet (32, 52) of a plasma torch to melt the spray feed stock and propel it onto an electrolyte surface (34, 54) where the spray feed stock flattens into lamellae layer upon solidification, where the layer (38, 59) is an anode coating with greater than 35 vol. % based on solids volume.

36 MATERIALS SCIENCE↗
DOE OSTI2011

THE RESPONSE OF A THREE-DIMENSIONAL SOLAR ATMOSPHERE TO WAVE-DRIVEN JETS

Global oscillations from the solar interior are, mainly, pressure-driven (p-modes) oscillations with a peak power of a five-minute period. These oscillations are considered to manifest in many phenomena in the lower solar atmosphere, most notably, in spicules. These small-scale jets may provide the key to understanding the powering mechanisms of the transition region (TR) and lower corona. Here, we simulate the formation of wave-driven (type-I) spicule phenomena in three dimensions and the transmission of acoustic waves from the lower chromosphere and into the corona. The outer atmosphere oscillates in response to the jet formation, and in turn, we reveal the formation of a circular seismic surface wave, which we name as a Transition Region Quake (TRQ). The TRQ forms as a consequence of an upward propelling spicular wave train that repeatedly punctures and energizes the TR. The steep density gradient enables the TRQ to develop and radially fan outward from the location where the spicular plasma column impinges the TR. We suggest the TRQ formation as a formidable mechanism in continuously sustaining part of the energy budget of the TR. We present a supporting numerical model which allow us to determine the level of energy dumping at the TR by upward-propagating p-modes. Upon applying a wavelet analysis on our simulations we identify the presence of a chromospheric cavity which resonates with the jet propagation and leaves behind an oscillatory wake with a distinctive periodicity. Through our numerical analysis we also discover type-I spicule turbulence leading to a convection-based motion in the low corona.

42 ENGINEERING↗
DOE OSTI2025

Obtaining Real Production Data Through On-Component Printed SIR Patterns

Cleanliness validation of printed circuit assemblies has become increasingly important as electronic assemblies become smaller, denser, and more challenging to clean, prompting an increase in reliance in custom solutions. With increasingly fast paced development cycles, long lead times and costs of quality custom surrogate test boards become prohibitive in obtaining cleanliness data that is a true representative of the final product. In this study, aerosol jet printing, an additive manufacturing technology for electronics, was used to manufacture surface insulation resistance (SIR) test structures that were evaluated on their ability to detect cleanliness defects and remain stable when clean, as well as their survivability to standard electronics wash processes. Additionally, in an effort to further increase the agility of true product testing, SIR test structures were printed directly onto ball-grid-arrays (BGAs) and tested the survivability of conformally printed leads for data acquisition. SIR test structures displayed good wash survivability on standard FR4 and BGAs, including wraparounds for on-component prints, and high sensitivity to cleanliness defects. The presented results demonstrate the feasibility of printed SIR structures as a quick-turn, highly customizable solution for wash validation with potential for increased fidelity cleanliness testing.

SIR, Additive Manufacturing, Printed Electronics, ↗
DOE OSTI2012

A NON-RADIAL ERUPTION IN A QUADRUPOLAR MAGNETIC CONFIGURATION WITH A CORONAL NULL

We report one of the several homologous non-radial eruptions from NOAA active region (AR) 11158 that are strongly modulated by the local magnetic field as observed with the Solar Dynamic Observatory. A small bipole emerged in the sunspot complex and subsequently created a quadrupolar flux system. Nonlinear force-free field extrapolation from vector magnetograms reveals its energetic nature: the fast-shearing bipole accumulated {approx}2 Multiplication-Sign 10{sup 31} erg free energy (10% of AR total) over just one day despite its relatively small magnetic flux (5% of AR total). During the eruption, the ejected plasma followed a highly inclined trajectory, over 60 Degree-Sign with respect to the radial direction, forming a jet-like, inverted-Y-shaped structure in its wake. Field extrapolation suggests complicated magnetic connectivity with a coronal null point, which is favorable of reconnection between different flux components in the quadrupolar system. Indeed, multiple pairs of flare ribbons brightened simultaneously, and coronal reconnection signatures appeared near the inferred null. Part of the magnetic setting resembles that of a blowout-type jet; the observed inverted-Y structure likely outlines the open field lines along the separatrix surface. Owing to the asymmetrical photospheric flux distribution, the confining magnetic pressure decreases much faster horizontally than upward. This special field geometry likely guided the non-radial eruption during its initial stage.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Multi-layer Printing of Complex Antennas Using Aerosol Jet Technology (CRADA NFE-18-07315 Final Report)

This project demonstrated the feasibility of producing multilayer radio-frequency (RF) and microwave-frequency components using aerosol jet additive manufacturing technology. Funded by the U.S. Department of energy, Advanced Manufacturing Office, this effort focused on novel stacked component designs for devices such as antennas, electronic filters, resistive/inductive/capacitive (RLC) components, and transmission lines. Our approach to RF/microwave component fabrication by aerosol jet printing has the potential to reduce component size, improve performance characteristics, and allow devices to be fabricated on non-planar surfaces. Specifically, folded micro-patch antenna designs were fabricated by stacking layers of conductors and dielectrics printed in sequence using Optomec’s aerosol jet technology. ORNL supported the effort by providing design input on printing parameters and characterizing the performance of printed structures. ORNL identified suitable stacked antenna designs, produced finite element models (FEM) in high-frequency simulation software (HFSS), and provided the designs to Optomec for printing. After printing, the devices were tested and characterized at ORNL to determine the frequency response and material characteristics of the printed components. These proof-of-principle devices will provide feedback on printing parameters, optimizations for the FEM models, and a path for more complex multilayer device designs.

42 ENGINEERING↗
NASA NTRS1982

Improved Stirling engine performance using jet impingement

Of the many factors influencing the performance of a Stirling engine, that of transferring the combustion gas heat into the working fluid is crucial. By utilizing the high heat transfer rates obtainable with a jet impingement heat transfer system, it is possible to reduce the flame temperature required for engine operation. Also, the required amount of heater tube surface area may be reduced, resulting in a decrease in the engine nonswept volume and a related increase in engine efficiency. A jet impingement heat transfer system was designed by Rasor Associates, Inc., and tested in the GPU-3 Stirling engine at the NASA Lewis Research Center. For a small penalty in pumping power (less than 0.5% of engine output) the jet impingement heat transfer system provided a higher combustion-gas-side heat transfer coefficient and a smoothing of heater temperature profiles resulting in lower combustion system temperatures and a 5 to 8% increase in engine power output and efficiency.

Johnson, D. C.↗