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  • 1
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    Pre-Launch Testing of GPS Receivers for Geodetic Space Missions (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The methodology used and the results obtained in the pre-flight testing of the Blackjack Global Positioning System (GPS) space receiver for the Vegetation Canopy Lidar Mission (VCL) and the Ice, Cloud, and Land Elevation Satellite (ICESat) spacecraft is described. Both real and simulated signals were used to: (1) assess the accuracy and coverage of the navigation solutions, (2) assess the accuracy and stability of the 1-PPS timing signal, (3) assess the precision of the carrier phase observable, and (4) measure the cold-start time to first fix. In addition, an anechoic chamber was used to measure the antenna phase centers with millimeter-level precision. While the test results have generally been excellent and are discussed in this paper, emphasis is placed on describing the test methodology. It is anticipated that future geodetic satellite missions using GPS for navigation, timing, and precise orbit determination (POD) can employ the same tests for pre-launch performance assessment of their particular receiver.
    Keywords: Composite Materials
    Type: Global Positioning Systems; Jan 01, 2000; Salt Lake City, NV; United States
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  • 2
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    Oscillation pressure device for dynamic calibration of pressure transducers (1987)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Method and apparatus for obtaining dynamic calibrations of pressure transducers. A calibration head (15), a flexible tubing (23) and a bellows (20) enclose a volume of air at atmospheric pressure with a transducer (11) to be calibrated subject to the pressure inside the volume. All of the other apparatus in the drawing apply oscillations to bellows (20) causing the volume to change thereby applying oscillating pressures to transducer (11) whereby transducer (11) can be calibrated.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 3
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    Reference Material Kydex(registered trademark)-100 Test Data Message for Flammability Testing (2003)
    In:  CASI
    Details
    Publication Date: 2018-06-12
    Description: The Marshall Space Flight Center (MSFC) Materials and Processes Technical Information System (MAPTIS) database contains, as an engineering resource, a large amount of material test data carefully obtained and recorded over a number of years. Flammability test data obtained using Test 1 of NASA-STD-6001 is a significant component of this database. NASA-STD-6001 recommends that Kydex 100 be used as a reference material for testing certification and for comparison between test facilities in the round-robin certification testing that occurs every 2 years. As a result of these regular activities, a large volume of test data is recorded within the MAPTIS database. The activity described in this technical report was undertaken to mine the database, recover flammability (Test 1) Kydex 100 data, and review the lessons learned from analysis of these data.
    Keywords: Composite Materials
    Type: 5th Conference on Aerospace Materials, Processes, and Environmental Technology; NASA/CP-2003-212931
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  • 4
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    Thermal Analysis in Support of the Booster Separation Motor Crack Investigation (2002)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: During a post-test inspection of a Booster Separation Motor (BSM) from a Lot Acceptance Test (LAT), a crack was noticed in the graphite throat. Since this was an out-of-family occurrence, an investigation team was formed to determine the cause of the crack. This paper will describe thermal analysis techniques used in support of this investigation. Models were generated to predict gradients in nominal motor conditions, as well as potentially anomalous conditions. Analysis was also performed on throats that were tested in the Laser Hardened Material Evaluation Laboratory (LHMEL). Some of these throats were pre-cracked, while others represented configurations designed to amplify effects of thermal stresses. Results from these analyses will be presented in this paper.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Twelfth Thermal and Fluids Analysis Workshop; NASA/CP-2002-211783
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  • 5
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    Second NASA Advanced Composites Technology Conference (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The conference papers are presented. The Advanced Composite Technology (ACT) Program is a major multi-year research initiative to achieve a national goal of technology readiness before the end of the decade. Conference papers recorded results of research in the ACT Program in the specific areas of automated fiber placement, resin transfer molding, textile preforms, and stitching as these processes influence design, performance, and cost of composites in aircraft structures. These papers will also be included in the Ninth Conference Proceedings to be published by the Federal Aviation Administration as a separate document.
    Keywords: Composite Materials
    Type: NASA-CP-3154 , L-17106 , NAS 1.55:3154
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  • 6
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    Experimental and Computational Boundary-Layer Studies In a Supersonic Two-Dimensional Nozzle (1998)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: Experiments and computations were carried out on the adiabatic laminar boundary layer developing along the surfaces of a two-dimensional supersonic nozzle, consisting of upper and lower contoured nozzle blocks and flat sidewalls. Two- and three-dimensional Navier-Stokes codes, as well as two-dimensional boundary-layer codes were employed. These codes were adapted to the characteristics of a specific wind tunnel nozzle, so that their numerical results could be directly compared with experimental data obtained in the same nozzle. Such comparisons were made for the boundary-layer growth on the nozzle contoured surfaces, and for the boundary-layer growth, surface streamlines and surface shear on the sidewalls. The three-dimensional Navier-Stokes code was found to be the only one to correctly predict the mean laminar boundary-layer flow on both the sidewalls and the contoured surfaces. Theory and experiment both indicated that the sidewall flow is highly three-dimensional, with non-uniform shear, corner vortices and a boundary layer strongly distorted by cross flows induced by lateral pressure gradients.
    Keywords: Fluid Mechanics and Thermodynamics
    Format: text
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  • 7
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    Interactions Between Klebanoff Modes and TS Waves (1996)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: The Harmonic Point Source (HPS) is the simplest possible form of 3D disturbance yet even this case is not fully understood. One of the characteristics of HPS generated Tolmien Schlichting (TS) waves is that the maximum rms amplitude downstream of the source occurs away from the centerline. As the waves fan out in the spanwise direction they can encounter Klebanoff modes (weak streamwise vortices) which may be present as background disturbances within the layer. The vortices originate near the leading edge and they appear to be caused by amplification of almost immeasurably small nonuniformities in the free stream. The vortices can be steady but they often appear as very low frequency background unsteadiness (as observed by Klebanoff). The vortices locally distort the mean flow and therefore (by definition) they are nonlinear phenomena e.g. the growth rate of the TS waves is altered. Kendall (private communication) has demonstrated total suppression of TS waves by deliberately introducing strong vortices generated by a delta wing. For the very weak vortices that are often encountered in experiments, their effect is characterized by a local reduction in the rms TS magnitude. The laminar wake behind a fine wire is used to generate Klebanoff modes and the interactions with HPS generated TS waves are explored in a controlled manner. It is shown that a proportion of the reduction in the observed TS magnitude can be attributed to washout of the phase-averaged signals owing to phase jitter.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: 49th Annual Meeting, Division of Fluid Dynamics of the American Physical Society; Nov 24, 1996 - Nov 26, 1996; Syracuse, NY; United States
    Format: text
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  • 8
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    Experimental and Computational Boundary-Layer Studies in a Supersonic Two-Dimensional Nozzle (1996)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: Calculations have been carried out on the adiabatic laminar boundary layer developing on the surface of a two-dimensional supersonic nozzle, consisting of contoured nozzle blocks and flat sidewalls. Two- and three-dimensional Navier-Stokes codes, as well as two-dimensional boundary-layer codes have been employed. Thee codes have been adapted to the characteristics of a specific wind tunnel nozzle, so that their numerical results could be directly compared with experimental data obtained in the same nozzle. Such comparisons have been made for the boundary-layer growth on the contoured nozzle, and for the boundary-layer growth, surface streamlines and surface shear on the sidewalls. The three-dimensional Navier-Stokes code was found to be the only one to correctly predict the mean boundary-layer flow on both the sidewalls and the contoured nozzle. Theory and experiment both indicate that the sidewall flow is highly three-dimensional, with non-uniform shear, comer vortices and a boundary layer strongly distorted by cross flows induced by lateral pressure gradients.
    Keywords: Fluid Mechanics and Thermodynamics
    Format: text
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  • 9
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    High Resolution Experiments of Compressible Turbulence Interacting With Shock Waves (2000)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: Most of the second year of our research program focused on exploring the potentially favorable the effects of expansion waves on homogeneous and isotropic turbulence, which is formed downstream of a grid. Expansion waves are associated with compressible flows and may reduce the drag over airfoils by suppressing turbulence. In the very few previous investigations of interactions of turbulence with expansion waves the effects due to stabilizing streamline curvature substantially masked the effects of turbulence suppression due to flow expansion though the waves. In the present flow configuration planar expansion waves interact with grid generated turbulence in our high-resolution shock tube research facility. This approach will assess directly the effects of the interaction on turbulence. The first objective of our study was to identify the nature of expansion waves present in our shock tube facility. Our time-dependent numerical simulations of the flow in our facility indicated the existence of two regions of traveling expansion waves. The system of expansion waves utilized in this investigation is generated by the exiting shock wave and the induced flow behind it at the end of the driver. Several new measuring techniques are being developed which are capable of providing velocity-gradient-related quantities in compressible flows for the first time.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: HBCUs/OMUs Research Conference Agenda and Abstracts; 14; NASA/TM-2000-210042
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  • 10
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    Boundary Layer Receptivity to Three-Dimensional Freestream Disturbances at Two-Dimensional Roughness (1997)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: The receptivity of a laminar boundary layer to an isolated three-dimensional convected disturbance is investigated in a low-speed wind tunnel experiment. The disturbance is created by the short-duration pulsed displacement of a small low-aspect-ratio wing located upstream of a flat plate. The height of the wing is set so that the convected disturbance grazes the edge of the flat-plate boundary layer. A receptivity site is provided by a two-dimensional roughness strip on the surface of the plate. The different propagation speeds of acoustic, convected and instability waves cause the various wave packets from the pulsed displacement to arrive at a downstream measurement station at different times, separating the phenomena and allowing them to be studied independently. Ensemble- averaged measurements are made with and without roughness on the plate. Preliminary analysis of the measurements suggest the presence of a two-dimensional T-S wave packet arising from an interaction between an acoustic wave and the roughness, and a three-dimensional T-S wave packet arising from an interaction between the localized convected disturbance and the roughness strip. The growth rates and spatial characteristics of the disturbances and the instability wave packets are measured as they propagate downstream.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: DFD 1997 Meeting of the American Physical Society; Nov 23, 1997 - Nov 25, 1997; San Francisco, CA; United States
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