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  • 1
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    Unknown
    Macomb, Ill., etc. : Periodicals Archive Online (PAO)
    Journal of Geography. 40 (1941:Jan./Dec.) 307 
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  • 2
    Publication Date: 2015-12-09
    Description: Landsat-7 and RADARSAT-1/2 satellite images are used to produce the most comprehensive record of glacier motion in the Canadian High Arctic to date, and to characterize spatial and temporal variability in ice flow over the past ~15 years. This allows us to assess whether dynamically-driven glacier change can be attributed to “surging” or “pulsing”, or whether other mechanisms are involved. RADAR velocity mapping allows annual regional dynamic discharge (iceberg calving) to be calculated for 2000 and the period 2011–2015 (yielding a mean regional discharge of 2.21 ± 0.68 Gt a −1 ) and velocities derived from feature tracking of optical imagery allow for annual dynamic discharge to be calculated for select glaciers from 1999–2010. Since ~2011, several of the major tidewater-terminating glaciers within the region have decelerated and their dynamic discharge has decreased. Trinity and Wykeham Glaciers (Prince of Wales Icefield) represent a notable departure from this pattern as they have generally accelerated over the study period. The resulting increase in dynamic discharge from these glaciers entirely compensates (within error limits) for the decrease in discharge from the other tidewater glaciers across the study region. These two glaciers accounted for ~62% of total regional dynamic discharge in winter 2015 (compared to ~22% in 2000), demonstrating that total ice discharge from the Canadian High Arctic can be sensitive to variations in flow of just a few tidewater glaciers.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 3
    Publication Date: 1941-11-01
    Print ISSN: 0022-1341
    Electronic ISSN: 1752-6868
    Topics: Geography
    Published by Taylor & Francis
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  • 4
    Publication Date: 2019-06-28
    Description: Steady, incompressible, turbulent, swirl-free flow through a circular-to-rectangular transition duck was studied experimentally. The cross-sectional area remains the same at the exit as at the inlet, but varies through the transition section to a maximum value approximately 15 percent above the inlet value. The cross-sectional geometry everywhere along the duct is defined by the equation of a superellipse. Mean and turbulence data were accumulated utilizing pressure and hot-wire instrumentation at five stations along the test section. Data are presented for operating bulk Reynolds numbers of 88,000 and 390,000. Measured quantities include total and static pressure, the three components of the mean velocity vector, and the six components of the Reynolds stress tensor. In addition to the transition duct measurements, a hot-wire technique which relies on the sequential use of single rotatable normal and slant-wire probes was proposed. The technique is applicable for measurement of the total mean velocity vector and the complete Reynolds stress tensor when the primary flow is arbitrarily skewed relative to a plane which lies normal to the probe axis of rotation.
    Keywords: AERODYNAMICS
    Type: NASA-TM-105210 , E-6522 , NAS 1.15:105210
    Format: application/pdf
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  • 5
    Publication Date: 2018-06-05
    Description: The Parametric Inlet is an innovative concept for the inlet of a gas-turbine propulsion system for supersonic aircraft. The concept approaches the performance of past inlet concepts, but with less mechanical complexity, lower weight, and greater aerodynamic stability and safety. Potential applications include supersonic cruise aircraft and missiles. The Parametric Inlet uses tailored surfaces to turn the incoming supersonic flow inward toward an axis of symmetry. The terminal shock spans the opening of the subsonic diffuser leading to the engine. The external cowl area is smaller, which reduces cowl drag. The use of only external supersonic compression avoids inlet unstart--an unsafe shock instability present in previous inlet designs that use internal supersonic compression. This eliminates the need for complex mechanical systems to control unstart, which reduces weight. The conceptual design was conceived by TechLand Research, Inc. (North Olmsted, OH), which received funding through NASA s Small-Business Innovation Research program. The Boeing Company (Seattle, WA) also participated in the conceptual design. The NASA Glenn Research Center became involved starting with the preliminary design of a model for testing in Glenn s 10- by 10-Foot Supersonic Wind Tunnel (10 10 SWT). The inlet was sized for a speed of Mach 2.35 while matching requirements of an existing cold pipe used in previous inlet tests. The parametric aspects of the model included interchangeable components for different cowl lip, throat slot, and sidewall leading-edge shapes and different vortex generator configurations. Glenn researchers used computational fluid dynamics (CFD) tools for three-dimensional, turbulent flow analysis to further refine the aerodynamic design.
    Keywords: Aircraft Design, Testing and Performance
    Type: Research and Technology 2004; NASA/TM-2005-213419
    Format: application/pdf
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  • 6
    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
    Format: text
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  • 7
    Publication Date: 2019-07-13
    Description: Three applications of the ethylene trace-gas technique to high-speed flows are described: flow-field tracking, air-to-air mixing, and bleed mass-flow measurement. The technique involves injecting a non-reacting gas (ethylene) into the flow field and measuring the concentration distribution in a downstream plane. From the distributions, information about flow development, mixing, and mass-flow rates can be dtermined. The trace-gas apparatus and special considerations for use in high-speed flow are discussed. A description of each application, including uncertainty estimates is followed by a demonstrative example.
    Keywords: AERODYNAMICS
    Type: NASA-TM-106491 , AIAA PAPER 94-0733 , E-8478 , NAS 1.15:106491 , Aerospace Meeting and Exhibit; Jan 10, 1994 - Jan 13, 1994; Reno, NV; United States
    Format: application/pdf
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  • 8
    Publication Date: 2019-07-13
    Description: The results of an experimental calibration of the NASA Glenn Research Center 16 in. Mass-Flow Plug (MFP) are presented and compared to a previously obtained calibration of a 15 in. Mass-Flow Plug. An ASME low-beta, long-radius nozzle was used as the calibration reference. The discharge coefficient for the ASME nozzle was obtained by numerically simulating the flow through the nozzle from the WIND-US code. The results showed agreement between the 15 and 16 in. MFPs for area ratios (MFP to pipe area ratio) greater than 0.6 but deviate at area ratios below this value for reasons that are not fully understood. A general uncertainty analysis was also performed and indicates that large uncertainties in the calibration are present for low MFP area ratios.
    Keywords: Research and Support Facilities (Air)
    Type: NASA/TM-2014-218128 , FEDSM2012-72266 , E-18891 , ASME 2012 Fluids Engineering Division Summer Meeting; Jul 08, 2012 - Jul 12, 2012; Rio Grande; Puerto Rico
    Format: application/pdf
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  • 9
    Publication Date: 2019-07-13
    Description: Experimental investigations of specific flow phenomena, e.g., Shock Wave Boundary-Layer Interactions (SWBLI), provide great insight to the flow behavior but often lack the necessary details to be useful as CFD validation experiments. Reasons include: 1.Undefined boundary conditions Inconsistent results 2.Undocumented 3D effects (CL only measurements) 3.Lack of uncertainty analysis While there are a number of good subsonic experimental investigations that are sufficiently documented to be considered test cases for CFD and turbulence model validation, the number of supersonic and hypersonic cases is much less. This was highlighted by Settles and Dodsons [1] comprehensive review of available supersonic and hypersonic experimental studies. In all, several hundred studies were considered for their database.Of these, over a hundred were subjected to rigorous acceptance criteria. Based on their criteria, only 19 (12 supersonic, 7 hypersonic) were considered of sufficient quality to be used for validation purposes. Aeschliman and Oberkampf [2] recognized the need to develop a specific methodology for experimental studies intended specifically for validation purposes.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: GRC-E-DAA-TN25302 , 2015 AJK Fluids Engineering Division Summer Meeting; Jul 26, 2015 - Jul 31, 2015; Seoul; Korea, Democratic People''s Republic of
    Format: application/pdf
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  • 10
    Publication Date: 2019-07-13
    Description: Preliminary results of an experimental investigation of a Mach 2.5 two-dimensional axisymmetric shock-wave/boundary-layer interaction (SWBLI) are presented. The purpose of the investigation is to create a SWBLI dataset specifically for CFD validation purposes. Presented herein are the details of the facility and preliminary measurements characterizing the facility and interaction region. The results will serve to define the region of interest where more detailed mean and turbulence measurements will be made.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AJK2015-06342 , GRC-E-DAA-TN23733 , 2015 AJK Fluids Engineering Division Summer Meeting; Jul 26, 2015 - Jul 31, 2015; Seoul; Korea, Republic of
    Format: application/pdf
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