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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 1,027 records · Page 57
All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

Scale Model Acoustic Test Validation of IOP-SS Water Prediction using Loci-STREAM-VoF

The Scale Model Acoustic Test (SMAT) is a 5% scale test of the Space Launch System (SLS), which is currently being designed at Marshall Space Flight Center (MSFC). SMAT consists of a 5% scale representation of the ignition overpressure sound-suppression system (IOP-SS) that is being tested to quantify the water flow and induced air entrainment in and around the mobile launcher exhaust hole. This data will be compared with computational fluid dynamics (CFD) simulations using the newly developed Loci-STREAM Volume of Fluid (VoF) methods. Compressible and incompressible VoF methods have been formulated, and are currently being used to simulate the water flow of SMAT IOP-SS. The test data will be used to qualitatively and quantitatively assess and validate the VoF methods.

Nielsen, Tanner↗
NASA NTRS1961

Geomagnetic Field Distortion by a Solar Stream as a Mechanism for the Production of Polar Aurora and Electrojets

This paper describes a mechanism for charge separation in the geomagnetically trapped radiation which may account for some observed phenomena associated with the polar aurora and the electrojet current systems. The following development is proposed: given that there exist eastward or westward longitudinal gradients in the geomagnetic field resulting from distortion of the geomagnetic field by solar streams, if the trapped radiation is adiabatic in character, radial drift separation of positive and negative charged particles must occur. It follows that, for bounded or irregular distributions of plasma number density in such an adiabatic - drift region, electric fields will arise. The origin of such electric fields will not arrest the drift separation of the charged particles, but will contribute to exponential growth of irregularities in the trapped plasma density. An adiabatic acceleration mechanism is described, which is based on incorporating the electrostatic energy of the particle in the energy function for the particle. Direct consequences of polarization of the geomagnetically trapped radiation will be the polar electrojet current systems and the polar aurora.

Kern, J. W.↗
NASA NTRS2011

Excited State Chemistry in the Free Stream of the NASA IHF Arc Jet Facility Observed by Emission Spectroscopy

Spectroscopic measurements of non-equilibrium emission were made in the free stream of the 60 megawatts Interaction Heating Facility at NASA Ames Research Center. In the visible near infrared wavelength region, the most prominent emission was from molecular N2, and in the ultra violet region, the spectra were dominated by emission from molecular NO. The only atomic lines observed were those of copper (an erosion product of the electrodes). The bands of the 1st Positive system of N2 (if B is true then A is true) differed significantly from spectra computed spectra assuming only thermal excitation, suggesting overpopulation of the high vibrational states of the B state of N2. Populations of these high vibrational levels (peaking at v (sub upper) equals 13) of the N2 B state were determined by scaling simulated spectra; calculations were performed for each upper vibrational state separately. The experimental-theoretical procedure was repeated for several radial positions away from the nozzle axis to obtain spatial distributions of the upper state populations; rotational symmetry of the flow was assumed in simulations. The overpopulation of the high vibrational levels has been interpreted as the effect of inverse pre-dissociation of neutral atoms in the N2 A state, which populates the N2 B state through a level crossing process at v (sub upper) is greater than 10.

arc-jet testing↗
NASA NTRS2015

Relativistic Electron Response to the Combined Magnetospheric Impact of a Coronal Mass Ejection Overlapping with a High-Speed Stream: Van Allen Probes Observations

During early November 2013, the magnetosphere experienced concurrent driving by a coronal mass ejection (CME) during an ongoing high-speed stream (HSS) event. The relativistic electron response to these two kinds of drivers, i.e., HSS and CME, is typically different, with the former often leading to a slower buildup of electrons at larger radial distances, while the latter energizing electrons rapidly with flux enhancements occurring closer to the Earth. We present a detailed analysis of the relativistic electron response including radial profiles of phase space density as observed by both Magnetic Electron and Ion Sensor (MagEIS) and Relativistic Electron Proton Telescope instruments on the Van Allen Probes mission. Data from the MagEIS instrument establish the behavior of lower energy (<1 MeV) electrons which span both intermediary and seed populations during electron energization. Measurements characterizing the plasma waves and magnetospheric electric and magnetic fields during this period are obtained by the Electric and Magnetic Field Instrument Suite and Integrated Science instrument on board Van Allen Probes, Search Coil Magnetometer and Flux Gate Magnetometer instruments on board Time History of Events and Macroscale Interactions during Substorms, and the low-altitude Polar-orbiting Operational Environmental Satellites. These observations suggest that during this time period, both radial transport and local in situ processes are involved in the energization of electrons. The energization attributable to radial diffusion is most clearly evident for the lower energy (<1 MeV) electrons, while the effects of in situ energization by interaction of chorus waves are prominent in the higher-energy electrons.

Magnetosphere↗
NASA NTRS2016

Implementation of a Multichannel Serial Data Streaming Algorithm using the Xilinx Serial RapidIO Solution

In the current world of applications that use reconfigurable technology implemented on field programmable gate arrays (FPGAs), there is a need for flexible architectures that can grow as the systems evolve. A project has limited resources and a fixed set of requirements that development efforts are tasked to meet. Designers must develop robust solutions that practically meet the current customer demands and also have the ability to grow for future performance. This paper describes the development of a high speed serial data streaming algorithm that allows for transmission of multiple data channels over a single serial link. The technique has the ability to change to meet new applications developed for future design considerations. This approach uses the Xilinx Serial RapidIO LOGICORE Solution to implement a flexible infrastructure to meet the current project requirements with the ability to adapt future system designs.

RapidIO↗
NASA NTRS2017

Energy Release in the Solar Atmosphere from a Stream of Infalling Prominence Debris

Recent high-resolution and high-cadence extreme-ultraviolet (EUV) imaging has revealed a new phenomenon, impacting prominence debris, where prominence material from failed or partial eruptions can impact the lower atmosphere, releasing energy. We report a clear example of energy release and EUV brightening due to infalling prominence debris that occurred on 2011 September 7-8. The initial eruption of material was associated with an X1.8-class flare from AR 11283, occurring at 22:30 UT on 2011 September 7. Subsequently, a semicontinuous stream of this material returned to the solar surface with a velocity v greater than 150 km/s, impacting a region remote from the original active region between 00:20 and 00:40 UT on 2011 September 8. Using the Solar Dynamics Observatory/Atmospheric Imaging Assembly, the differential emission measure of the plasma was estimated throughout this brightening event. We found that the radiated energy of the impacted plasma was L(sub rad) approx. 10(exp 27) erg, while the thermal energy peaked at approx.10(exp 28) erg. From this we were able to determine the mass content of the debris to be in the range 2 x 10(exp 14) less than m less than 2 x 10(exp 15) g. Given typical prominence masses, the likely debris mass is toward the lower end of this range. This clear example of a prominence debris event shows that significant energy release takes place during these events and that such impacts may be used as a novel diagnostic tool for investigating prominence material properties.

Inglis, A. R.↗
NASA NTRS2018

The Formation and Early Evolution of Meteoroid Streams

This talk covers the ejection of particles from comets to the initial formation of a meteoroid stream. It presents new work on ejection velocity and unbound particles, and has a recurring focus on dust-to-meteoroid transition.

Moorhead, Althea↗
NASA NTRS2018

Resonance and Tones in Dual-Stream Nozzle Flows

A dual-stream nozzle configuration was studied numerically with the objective of predicting the appearance of tones and study their sources. It was found that some of the tones traced to a coupling between Strouhal shedding from the struts, which held different pieces of the nozzle together, and various duct acoustic modes. A focus of the work was on exploring the nature of the duct modes. First, elements of the numerical procedure were studied for a 4-strut nozzle, validating the results with existing experimental data. The approach was then applied to a 3-strut geometry and four different excitation methods. The predicted tones and associated duct modes are analyzed in detail.

Milanovic, Ivana↗
NASA NTRS2019

Evidence for Oscillating Two-Stream Instability and Spatial Collapse of Langmuir Waves in a Solar Type II Radio Burst

We present the high time resolution in situ observations of Langmuir waves, likely excited by an electron beam accelerated by a coronal-mass ejection-driven super-critical quasi-perpendicular interplanetary shock into its upstream solar wind, which happens to be the source region of a solar type II radio burst. We show that (1) these waves occur as coherent localized magnetic-field-aligned, one-dimensional wave packets with durations of a few milliseconds and with peak intensities well in excess of the threshold for strong turbulence processes, (2) they provide what is believed to be the first evidence for: (a) the oscillating two-stream instability (OTSI) L(sub 1) + L(sub 2) S/⟶ U + D, where L(sub 1) and L(sub 2), U and D, and S are the pump Langmuir waves, up- and down-shifted side bands, and ion sound waves, respectively, (b) a three-wave interaction U + D ⟶ T(sub 2f(sub pe)), where T(sub 2f(sub pe)) is the second harmonic electromagnetic wave, (3) they satisfy the threshold condition for formation of collapsing solitons, and (4) they are accompanied by their ponderomotive force induced density cavities with δn(sub p)/n(sub e) > δn(sub b)/n(sub e), where δn(sub p)/n(sub e) is the level of ponderomotive force induced density fluctuations and δn(sub b)/n(sub e) is that of the ambient fluctuations. These findings strongly suggest that the observed wave packets provide evidence for the collapsing solitons formed as a result of OTSI. The implication is that the strong turbulence processes probably play very important roles in excitation of type II radio emissions as well as in stabilization of shock-accelerated electron beams.

Sun radio radiation↗
NASA NTRS1994

An Approximate Kalman Filter for Ocean Data Assimilation; An Example with an Idealized Gulf Stream Model

A practical method of data assimilation for use with large, nonlinear, ocean general circulation models is explored. A Kalman filter based on approximations of the state error covariance matrix is presented, employing a reduction of the effective model dimension, the error's asymptotic steady-state limit, and a time-invariant linearization of the dynamic model for the error integration. The approximations lead to dramatic computational savings in applying estimation theory to large complex systems. We examine the utility of the approximate filter in assimilating different measurement types using a twin experiment of an idealized Gulf Stream. A nonlinear primitive equation model of an unstable east-west jet is studied with a state dimension exceeding 170,000 elements. Assimilation of various pseudo measurements is examined, including velocity, density, and volume transport at localized arrays, and realistic distributions of satellite altimetry and acoustic tomography observations. Results are compared in terms of their effects on the accuracies of the estimation. The approximate filter is shown to outperform a previous study that used an empirical nudging scheme. The examples demonstrate that useful approximate estimation errors can be computed in a practical manner for general circulation models.

['Kalman↗
NASA NTRS2000

Characteristics of three-dimensional quasi-geostrophic transient eddy propagation in the vicinity of a simulated Gulf Stream

Output of an eddy-resolving model of the North Atlantic is diagnosed in the vicinity of the Gulf Stream (GS), using the three-dimensional quasi-geostrophic transient wave activity flux diagnostic developed by Plumb [1986]. The model North Atlantic shows large transient wave activity along the model GS and along the edge of the Mediterranean Outflow. The fluxes show advection of wave activity by the GS from the separation point and radiation of wave activity from the GS in the top 1000 m.

boundary↗
NASA NTRSDate not supplied

A Review of Baseline Assumptions and Ersatz Waste Streams for Partial Gravity Habitats and Orbiting Microgravity Habitats

Highly efficient water management and recovery systems will be required to support human missions beyond the low Earth orbit of the International Space Station (ISS).A review of baseline assumptions for the human activities and associated water cycle in surface, partial gravity habitats and orbiting, microgravity habitats is conducted. The paper reviews and updates ersatz formulations and water flow rates for the main liquid water waste streams of urine, humidity condensate, hygiene, and laundry. A framework is provided to coordinate development of water recovery systems for 30-day crew occupancies under partial gravity with longer term, continuous occupancy in orbiting microgravity habitats and the Mars transit habitat.

Water Ersatz Habitat↗