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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 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRS2006

Interferometer for Low-Uncertainty Vector Metrology

A simplified schematic diagram of a tilt-sensing unequal-path interferometer set up to measure the orientation of the normal vector of one surface of a cube mounted on a structure under test is described herein. This interferometer has been named a "theoferometer" to express both its interferometric nature and the intention to use it instead of an autocollimating theodolite. The theoferometer optics are mounted on a plate, which is in turn mounted on orthogonal air bearings for near-360 rotation in azimuth and elevation. Rough alignment of the theoferometer to the test cube is done by hand, with fine position adjustment provided by a tangent arm drive using linear inchwormlike motors.

Toland, Ronald W.↗
NASA NTRS1993

Testing of the on-board attitude determination and control algorithms for SAMPEX

Algorithms for on-board attitude determination and control of the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) have been expanded to include a constant gain Kalman filter for the spacecraft angular momentum, pulse width modulation for the reaction wheel command, an algorithm to avoid pointing the Heavy Ion Large Telescope (HILT) instrument boresight along the spacecraft velocity vector, and the addition of digital sun sensor (DSS) failure detection logic. These improved algorithms were tested in a closed-loop environment for three orbit geometries, one with the sun perpendicular to the orbit plane, and two with the sun near the orbit plane - at Autumnal Equinox and at Winter Solstice. The closed-loop simulator was enhanced and used as a truth model for the control systems' performance evaluation and sensor/actuator contingency analysis. The simulations were performed on a VAX 8830 using a prototype version of the on-board software.

Mccullough, Jon D.↗
NASA NTRS2011

Challenges of Cold Conditioning and Static Testing the Second Ares Demonstration Motor (DM-2)

On August 31, 2010, a five-segment demonstration motor (DM) for the Ares program was successfully tested. A series of demonstration motors (DMs) will be tested in different conditioned environments to confirm they meet their design specifications. The second demonstration motor (DM-2) was the first cold motor. The motor needed to be subjected to sub-freezing temperatures for two months so that its internal propellant mean bulk temperature (PMBT) was approximately 40 F. Several challenges had to be overcome to make this a successful test. One challenge was to condition four field joints to get the O-rings approximately 32 F. This would be done by applying conditioning shrouds to externally cool each field joint after the test bay was pulled off. The purpose of this conditioning was to validate the new O-ring design and allow joint heaters to be eliminated. Another challenge was maintaining temperature requirements for components in the nozzle vectoring system. A separate heating system was used to warm these components during cold conditioning. There were 53 test objectives that required 764 channels of data to be recorded; 460 were specific to DM-2. This instrumentation had to be installed prior to conditioning, which meant the baseline process and timeline had to be modified to meet this time critical schedule.

Quinn, Shyla↗
NASA NTRS2016

Damping Effects of Drogue Parachutes on Orion Crew Module Dynamics

Because simulations of the Orion Crew Module (CM) dynamics with drogue parachutes deployed were under-predicting the amount of damping seen in free-flight tests, an attach-point damping model was applied to the Orion system. A key hypothesis in this model is that the drogue parachutes' net load vector aligns with the CM drogue attachment point velocity vector. This assumption seems reasonable and has historically produced good results, but has never been experimentally verified. The wake of the CM influences the drogue parachutes, which makes performance predictions of the parachutes difficult. Many of these effects are not currently modeled in the simulations. A forced oscillation test of the CM with parachutes was conducted in the NASA LaRC 20-Ft Vertical Spin Tunnel (VST) to gather additional data to validate and refine the attach-point damping model. A second loads balance was added to the original Orion VST model to measure the drogue parachute loads independently of the CM. The objective of the test was to identify the contribution of the drogues to CM damping and provide additional information to quantify wake effects and the interactions between the CM and parachutes. The drogue parachute force vector was shown to be highly dependent on the CM wake characteristics. Based on these wind tunnel test data, the attach-point damping model was determined to be a sufficient approximation of the parachute dynamics in relationship to the CM dynamics for preliminary entry vehicle system design. More wake effects should be included to better model the system.

Aubuchon, Vanessa V.↗
NASA NTRS2010

Understanding Solar Eruptions with SDO/HMI Measuring Photospheric Flows, Testing Models, and Steps Towards Forecasting Solar Eruptions

The imminent launch of Solar Dynamics Observatory (SDO) will carry the first full-disk imaging vector magnetograph, the Helioseismic and Magnetic Imager (HMI), into an inclined geosynchronous orbit. This magnetograph will provide nearly continuous measurements of photospheric vector magnetic fields at cadences of 90 seconds to 12 minutes with I" resolution, precise pointing, and unfettered by atmospheric seeing. The enormous data stream of ~1.5 Terabytes per day from SDO will provide an unprecedented opportunity to understand the mysteries of solar eruptions. These ground-breaking observations will permit the application of a new technique, the differential affine velocity estimator for vector magnetograms (DAVE4VM), to measure photospheric plasma flows in active regions. These measurements will permit, for the first time, accurate assessments of the coronal free energy available for driving CMEs and flares. The details of photospheric plasma flows, particularly along magnetic neutral-lines, are critical to testing models for initiating coronal mass ejections (CMEs) and flares. Assimilating flows and fields into state-of-the art 3D MHD simulations that model the highly stratified solar atmosphere from the convection zone to the corona represents the next step towards achieving NASA's Living with a Star forecasting goals of predicting "when a solar eruption leading to a CME will occur." This talk will describe these major science and predictive advances that will be delivered by SDO /HMI.

Schuck, Peter W.↗
NASA NTRS2012

Velocity Vector Field Visualization of Flow in Liquid Acquisition Device Channel

A capillary flow liquid acquisition device (LAD) for cryogenic propellants has been developed and tested in NASA Glenn Research Center to meet the requirements of transferring cryogenic liquid propellants from storage tanks to an engine in reduced gravity environments. The prototypical mesh screen channel LAD was fabricated with a mesh screen, covering a rectangular flow channel with a cylindrical outlet tube, and was tested with liquid oxygen (LOX). In order to better understand the performance in various gravity environments and orientations at different liquid submersion depths of the screen channel LAD, a series of computational fluid dynamics (CFD) simulations of LOX flow through the LAD screen channel was undertaken. The resulting velocity vector field visualization for the flow in the channel has been used to reveal the gravity effects on the flow in the screen channel.

McQuillen, John B.↗
DOE OSTI2024

Constraining Cosmology with Simulation-based inference and Optical Galaxy Cluster Abundance

We test the robustness of simulation-based inference (SBI) in the context of cosmological parameter estimation from galaxy cluster counts and masses in simulated optical datasets. We construct ``simulations'' using analytical models for the galaxy cluster halo mass function (HMF) and for the observed richness (number of observed member galaxies) to train and test the SBI method. We compare the SBI parameter posterior samples to those from an MCMC analysis that uses the same analytical models to construct predictions of the observed data vector. The two methods exhibit comparable performance, with reliable constraints derived for the primary cosmological parameters, ($\Omega_m$ and $\sigma_8$), and richness-mass relation parameters. We also perform out-of-domain tests with observables constructed from galaxy cluster-sized halos in the Quijote simulations. Again, the SBI and MCMC results have comparable posteriors, with similar uncertainties and biases. Unsurprisingly, upon evaluating the SBI method on thousands of simulated data vectors that span the parameter space, SBI exhibits worsened posterior calibration metrics in the out-of-domain application. We note that such calibration tests with MCMC is less computationally feasible and highlight the potential use of SBI to stress-test limitations of analytical models, such as in the use for constructing models for inference with MCMC.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1995

User's and test case manual for FEMATS

The FEMATS program incorporates first-order edge-based finite elements and vector absorbing boundary conditions into the scattered field formulation for computation of the scattering from three-dimensional geometries. The code has been validated extensively for a large class of geometries containing inhomogeneities and satisfying transition conditions. For geometries that are too large for the workstation environment, the FEMATS code has been optimized to run on various supercomputers. Currently, FEMATS has been configured to run on the HP 9000 workstation, vectorized for the Cray Y-MP, and parallelized to run on the Kendall Square Research (KSR) architecture and the Intel Paragon.

Chatterjee, Arindam↗
NASA NTRS1990

Control research in the NASA high-alpha technology program

NASA is conducting a focused technology program, known as the High-Angle-of-Attack Technology Program, to accelerate the development of flight-validated technology applicable to the design of fighters with superior stall and post-stall characteristics and agility. A carefully integrated effort is underway combining wind tunnel testing, analytical predictions, piloted simulation, and full-scale flight research. A modified F-18 aircraft has been extensively instrumented for use as the NASA High-Angle-of-Attack Research Vehicle used for flight verification of new methods and concepts. This program stresses the importance of providing improved aircraft control capabilities both by powered control (such as thrust-vectoring) and by innovative aerodynamic control concepts. The program is accomplishing extensive coordinated ground and flight testing to assess and improve available experimental and analytical methods and to develop new concepts for enhanced aerodynamics and for effective control, guidance, and cockpit displays essential for effective pilot utilization of the increased agility provided.

Gilbert, William P.↗
NASA NTRS1991

Real-time in-flight engine performance and health monitoring techniques for flight research application

Procedures for real time evaluation of the inflight health and performance of gas turbine engines and related systems were developed to enhance flight test safety and productivity. These techniques include the monitoring of the engine, the engine control system, thrust vectoring control system health, and the detection of engine stalls. Real time performance techniques were developed for the determination and display of inflight thrust and for aeroperformance drag polars. These new methods were successfully shown on various research aircraft at NASA-Dryden. The capability of NASA's Western Aeronautical Test Range and the advanced data acquisition systems were key factors for implementation and real time display of these methods.

Ray, Ronald J.↗
NASA NTRS1982

Testing of turbulent seals for rotordynamic coefficients

A facility has been developed for dynamic testing of straight and convergent tapered seals with the capability of measuring the radial and tangential force components which result from a circular centered orbit. The test apparatus causes the seal journal to execute small-eccentricity centered circular orbits within its clearance circle. Dynamic measurements are made and recorded of the seal displacement-vector components, and of the pressure field. The pressure field is integrated to yield seal tangential and radial reaction-force components. Representative test data are provided and discussed for straight seals.

Childs, D. W.↗
NASA NTRS1999

Computational Investigation of Fluidic Counterflow Thrust Vectoring

A computational study of fluidic counterflow thrust vectoring has been conducted. Two-dimensional numerical simulations were run using the computational fluid dynamics code PAB3D with two-equation turbulence closure and linear Reynolds stress modeling. For validation, computational results were compared to experimental data obtained at the NASA Langley Jet Exit Test Facility. In general, computational results were in good agreement with experimental performance data, indicating that efficient thrust vectoring can be obtained with low secondary flow requirements (less than 1% of the primary flow). An examination of the computational flowfield has revealed new details about the generation of a countercurrent shear layer, its relation to secondary suction, and its role in thrust vectoring. In addition to providing new information about the physics of counterflow thrust vectoring, this work appears to be the first documented attempt to simulate the counterflow thrust vectoring problem using computational fluid dynamics.

Hunter, Craig A.↗
DOE OSTI2025

Form factors for semi-leptonic $B_{(s)} \to D_{(s)}^∗\ell \nu_\ell$ decays

Semileptonic $B_{(s)}$ decays are of great phenomenological interestbecause they allow to extract CKM matrix elements or test lepton flavouruniversality. Taking advantage of existing data, we explore extractingform factors for vector final states using the narrow widthapproximation. Based on RBC/UKQCD's set of 2+1 flavour gauge fieldensembles with Shamir domain-wall fermion and Iwasaki gauge fieldaction, we study semileptonic $B_{(s)}$ decays using domain-wallfermions for light, strange and charm quarks, whereas bottom quarks aresimulated with the relativistic heavy quark (RHQ) action. Exploratoryresults for $B_s \to D_s^* \ell \nu_\ell$ are presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1978

Low speed aerodynamic characteristics of a vectored-engine-over-wing configuration

An investigation has been conducted in the Langley V/STOL tunnel to determine the low speed aerodynamic characteristics of a close-coupled canard-wing configuration using spanwise blowing and a vectored-engine-over-wing powered lift concept. The effects of spanwise blowing in conjunction with thrust vectoring are discussed. These effects were studied at M = 0.19 for a range of model angle of attack and engine nozzle pressure ratio. The results indicate combined use of spanwise blowing and thrust vectoring can provide significant performance improvements throughout the angle-of-attack range tested.

Leavitt, L. D.↗
NASA NTRS1983

Advanced technology exhaust nozzle development

The requirement for greater tactical aircraft operational capabilities has led to increasing research emphasis on the refinement of engine/airframe integration methods and exhaust nozzle flexibility. A major prospective advancement in the development of these capabilities takes the form of multifunctional exhaust nozzle systems with thrust reversal and thrust vectoring features, whose operation will be shared by both airframe and powerplant control systems. Attention is presently given to the two-dimensional convergent-divergent and single expansion ramp nozzle designs, with emphasis on the variable geometry mechanical systems by which they assume cruising flight, vectoring, and thrust reversal operations. The nozzles have been wind tunnel model-tested for the cases of the F-18 fighter and a supersonic cruise configuration concept.

Dusa, D. J.↗
NASA NTRS1984

Compressional features in the Tharsis Region of Mars: Orientations and Timing of Deformation

The Tharsis ridge system appears to form a great circle around the major volcanoes. The roughly circumferential orientation of these ridges could be interpreted as the formation of a ridge system in response to a single stress field with a center near Pavonis Mons. Wise, et al. (1979) plotted the perpendiculars to strikes of ridges on the eastern flanks of Tharsis as great circles on the upper hemisphere of an equal area net. In order to further test for circular symmetry and possible other influences on ridge orientations, normals to vector means of ridge orientations were calculated using over 1850 digitized ridge segments sampled in 10 degree boxes. Orientations of individual ridge segments were weighted by their lengths, and the magnitudes of normals to vectors means were weighted by cummulative length of the ridge segments. Normals to vector means with magnitudes less than 100 km are not shown. Assuming a single fold origin for ridges, the resulting plot shows compressive stress trajectories for the ridges in the Tharsis region. The averaged compressive stress orientation around Tharsis confirm the suggestion by Wise, et al. that the ridge system is not concentric to any single point.

Watters, T. R.↗
NASA NTRS1988

The two axis motion simulator for the large space simulator at ESTEC (European Space Research and Technology Center)

The Large Space Simulator at the European Space Research and Technology Center (ESTEC) has been recently equipped with a motion simulator capable of handling test items of 5 tons mass and having a volume of 7m in diameter and a length of 7m. The motion simulator has a modular set-up. It consists of a spinbox as a basic unit on which the test article is mounted and which allows continuous rotation (spin) . This spinbox can be used in two operational configurations; the spin axis is vertical to 30 degrees when mounted on a gimbalstand; and the spin axis is horizontal when mounted on a turntable-yoke combination. The turntable provides rotation within plus or minus 90 degrees. This configuration allows one to bring a test article to all possible relative positions viv-a-vis the sun vector (which is horizontal in this case). The spinbox allows fast rotation between 1 to 6 rpm or slow rotation between 1 to 25 rotations per day as well as positioning within plus or minus 0.4 degrees accuracy.

Beckel, Kurt A.↗
NASA NTRS1990

Hot gas ingestion characteristics and flow visualization of a vectored thrust STOVL concept

The study presents results obtained at the compressor face of a 9.2-percent scale vectored thrust model in ground effects from Phases I and II of a test program to evaluate the hot ingestion phenomena and control techniques, and to conduct flow visualization of the model flowfield in and out of ground effects, respectively. A description of the model, facility, a new model support system, and a sheet laser illumination system are provided. The findings contain the compressor face pressure and temperature distortions, compressor face temperature rise, and the environmental effects of the hot gas. The environmental effects include the ground plane temperature and pressure distributions, model airframe heating, and the location of the ground flow separation. Results from the sheet laser flow visualization test are also presented.

Johns, Albert L.↗