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Author : Anonim
Publisher : DIANE Publishing
Page : 51 pages
File Size : 48,7 Mb
Release : 2003
Category : Electronic
ISBN : 9781428995109
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
Page : 52 pages
File Size : 44,7 Mb
Release : 2018-05-30
Category : Electronic
ISBN : 1720480745
A ruggedized Doppler Global Velocimetry system has been built and tested at NASA Glenn Research Center. One component of planar velocity measurements of subsonic and supersonic flows from an under-expanded free jet are reported, which agree well with predicted values. An error analysis evaluates geometric and spectral error terms, and characterizes speckle noise in isotropic data. A multimode, fused fiber optic bundle is demonstrated to couple up to 650 mJ/pulse of laser light without burning or fiber ablation, and without evidence of Stimulated Brillouin Scattering or other spectral-broadening problems. Comparisons are made between spinning wheel data using illumination by freespace beam propagation and fiber optic beam delivery. The fiber bundle illumination is found to provide more spatially even and stable illumination than is typically available from pulsed Nd:YAG laser beams. The fiber bundle beam delivery is also a step toward making remote measurements and automatic real-time plume sectioning feasible in wind tunnel environments.Lant, Christian T.Glenn Research CenterVELOCITY MEASUREMENT; DOPPLER EFFECT; SUBSONIC FLOW; SUPERSONIC FLOW; FREE JETS; PULSED LASERS; COUPLING; FIBER OPTICS; BUNDLES; ERROR ANALYSIS; LIGHT BEAMS; ILLUMINATING
Author : National Aeronautics and Space Adm Nasa
Publisher : Independently Published
Page : 56 pages
File Size : 54,9 Mb
Release : 2018-10-27
Category : Science
ISBN : 1729330304
Doppler Global Velocimetry (DGV) is a new diagnostic tool that offers potential for flow field measurements in flight by acquiring three-component velocity data in near real-time during flight maneuvers. The feasibility of implementation of a flight DGV system aboard NASA's High-Angle-of-Attack Research Vehicle (HARV) was addressed in this work by identifying the essential characteristics of a flight measurement system and by performing calibration and error tests. Results from this work were: an outline that establishes a preliminary basis for system configurations by analyzing measurement errors, installation issues, and operating requirements; measurement of the accuracy of the DGV technique using a laboratory breadboard DGV system based on a frequency-doubled Nd: YAG laser and iodine Absorption Line Filter (ALF), which showed excellent agreement between the DGV data and pilot measurements on a laminar flow jet with velocities of up to 150 m/sec; a survey of DGV system components and technologies that are relevant to the design of a flight measurement system, including a survey of cameras for the next generation DGV receivers; an assessment of the candidate lasers and absorption line filters for the flight system, resulting in a near-term recommendation of Nd: host lasers and an iodine ALF for both flight and wind tunnel applications. Komine, Hiroshi and Brosnan, Stephen J. and Long, William H. and Stappaerts, Eddy A. Unspecified Center...
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
Page : 56 pages
File Size : 54,6 Mb
Release : 2018-07-06
Category : Electronic
ISBN : 1722360062
Doppler Global Velocimetry (DGV) is a new diagnostic tool that offers potential for flow field measurements in flight by acquiring three-component velocity data in near real-time during flight maneuvers. The feasibility of implementation of a flight DGV system aboard NASA's High-Angle-of-Attack Research Vehicle (HARV) was addressed in this work by identifying the essential characteristics of a flight measurement system and by performing calibration and error tests. Results from this work were: an outline that establishes a preliminary basis for system configurations by analyzing measurement errors, installation issues, and operating requirements; measurement of the accuracy of the DGV technique using a laboratory breadboard DGV system based on a frequency-doubled Nd: YAG laser and iodine Absorption Line Filter (ALF), which showed excellent agreement between the DGV data and pilot measurements on a laminar flow jet with velocities of up to 150 m/sec; a survey of DGV system components and technologies that are relevant to the design of a flight measurement system, including a survey of cameras for the next generation DGV receivers; an assessment of the candidate lasers and absorption line filters for the flight system, resulting in a near-term recommendation of Nd: host lasers and an iodine ALF for both flight and wind tunnel applications. Komine, Hiroshi and Brosnan, Stephen J. and Long, William H. and Stappaerts, Eddy A. Unspecified Center...
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
Page : 36 pages
File Size : 46,8 Mb
Release : 2018-08-17
Category : Electronic
ISBN : 1725724413
A new measurement technique is being developed by NASA to measure off-surface flow fields. This method, Doppler global velocimetry, will allow quantification of complex three-dimensional flow fields at video camera rates. The entire flow field structure within a selected plane is measured simultaneously rather than by scanned, point-by-point measurements using conventional laser velocimetry. To assess the capability of this new technique, velocity measurements of the vortical flow field above a thin 75-degree delta wing were made in the NASA Langley Basic Aerodynamics Research Tunnel. The operation of the system is described along with the techniques developed to process the output images. The results are then compared with similar measurements obtained using a three component laser velocimeter. Meyers, James F. Langley Research Center ...
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
Page : 30 pages
File Size : 42,8 Mb
Release : 2018-06
Category : Electronic
ISBN : 1720569320
The development of Doppler Global Velocimetry from a laboratory curiosity to a wind tunnel instrumentation system is discussed. This development includes system advancements from a single velocity component to simultaneous three components, and from a steady state to instantaneous measurement. Improvements to system control and stability are discussed along with solutions to real world problems encountered in the wind tunnel. This on-going development program follows the cyclic evolution of understanding the physics of the technology, development of solutions, laboratory and wind tunnel testing, and reevaluation of the physics based on the test results.Meyers, James F. and Lee, Joseph W. and Fletcher, Mark T. and South, Bruce W.Langley Research CenterHARDENING (SYSTEMS); WIND TUNNEL APPARATUS; LASER DOPPLER VELOCIMETERS; CCD CAMERAS; CALIBRATING; IODINE LASERS; ROTORS; NEODYMIUM LASERS; YAG LASERS; SUBSONIC WIND TUNNELS
Author : National Aeronautics and Space Adm Nasa
Publisher : Independently Published
Page : 62 pages
File Size : 54,8 Mb
Release : 2018-10-27
Category : Science
ISBN : 1729330096
Development of an optical, laser-based flow-field measurement technique for large wind tunnels is described. The technique uses laser sheet illumination and charged coupled device detectors to rapidly measure flow-field velocity distributions over large planar regions of the flow. Sample measurements are presented that illustrate the capability of the technique. An analysis of measurement uncertainty, which focuses on the random component of uncertainty, shows that precision uncertainty is not dependent on the measured velocity magnitude. For a single-image measurement, the analysis predicts a precision uncertainty of +/-5 m/s. When multiple images are averaged, this uncertainty is shown to decrease. For an average of 100 images, for example, the analysis shows that a precision uncertainty of +/-0.5 m/s can be expected. Sample applications show that vectors aligned with an orthogonal coordinate system are difficult to measure directly. An algebraic transformation is presented which converts measured vectors to the desired orthogonal components. Uncertainty propagation is then used to show how the uncertainty propagates from the direct measurements to the orthogonal components. For a typical forward-scatter viewing geometry, the propagation analysis predicts precision uncertainties of +/-4, +/-7, and +/-6 m/s, respectively, for the U, V, and W components at 68% confidence. Reinath, Michael S. Ames Research Center...
Author : Anonim
Publisher : Unknown
Page : 938 pages
File Size : 51,7 Mb
Release : 2001
Category : Government purchasing
ISBN : NYPL:33433031978004
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
Page : 30 pages
File Size : 52,7 Mb
Release : 2018-06-19
Category : Electronic
ISBN : 1721507817
A laser light scattering diagnostic for measurement of dynamic flow velocity at a point is described. The instrument is being developed for use in the study of propagating shock waves and detonation waves in pulse detonation engines under development at the NASA Glenn Research Center (GRC). The approach uses a Fabry-Perot interferometer to measure the Doppler shift of laser light scattered from small (submicron) particles in the flow. The high-speed detection system required to resolve the transient response as a shock wave crosses the probe volume uses fast response photodetectors, and a PC based data acquisition system. Preliminary results of measurements made in the GRC Mach 4, 10 by 25 cm supersonic wind tunnel are presented. Spontaneous condensation of water vapor in the flow is used as seed. The tunnel is supplied with continuous air flow at up to 45 psia and the flow is exhausted into the GRC laboratory-wide altitude exhaust system at pressures down to 0.3 psia. Seasholtz, Richard G. and Buggele, Alvin E. Glenn Research Center NASA/TM-2002-211503, NAS 1.15:211503, E-13269
Author : Anonim
Publisher : Unknown
Page : 1048 pages
File Size : 55,7 Mb
Release : 1999
Category : Aeronautics
ISBN : STANFORD:36105021810424
Author : Anonim
Publisher : Unknown
Page : 1118 pages
File Size : 45,6 Mb
Release : 1977
Category : Aeronautics
ISBN : MINN:31951000607706W
Author : Michael J. Kavaya
Publisher : Unknown
Page : 336 pages
File Size : 45,9 Mb
Release : 1999
Category : Coherent radar
ISBN : PSU:000043203673
The 10th conference on coherent laser radar technology and applications is the latest in a series beginning in 1980, which provides a forum for exchange of information on recent events, current status, and future directions of coherent laser radar (or lidar or lader) technology and applications. This conference emphasizes the latest advancements in the coherent laser radar field, including theory, modeling, components, systems, instrumentation, measurements, calibration, data processing techniques, operational uses, and comparisons with other remote sensing technologies.
Author : Anonim
Publisher : Unknown
Page : 776 pages
File Size : 51,8 Mb
Release : 2000
Category : Mechanics, Applied
ISBN : OSU:32435065742082
Author : Harvey H. Hubbard
Publisher : Unknown
Page : 620 pages
File Size : 42,5 Mb
Release : 1991
Category : Aerodynamic noise
ISBN : STANFORD:36105024722329
Author : National Aeronautics & Space Administration
Publisher : Unknown
Page : 148 pages
File Size : 42,8 Mb
Release : 2003-09
Category : Aeronautics
ISBN : 0160678951
