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Author :
Publisher : DIANE Publishing
ISBN 13 : 1428995102
Total Pages : 51 pages
Book Rating : 4.4/5 (289 download)
Download or read book Doppler Global Velocimetry at NASA Glenn Research Center: System Discussion and Results written by and published by DIANE Publishing. This book was released on 2003 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781720480747
Total Pages : 52 pages
Book Rating : 4.4/5 (87 download)
Download or read book Doppler Global Velocimetry at NASA Glenn Research Center written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-30 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 : United States. National Aeronautics and Space Administration
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (589 download)
Download or read book Doppler Global Velocimetry at Nasa Glenn Research Center: System Discussion and Results ... Nasa/cr--2003-212179 ... National Aeronautics and written by United States. National Aeronautics and Space Administration and published by . This book was released on 2003* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781722360061
Total Pages : 56 pages
Book Rating : 4.3/5 (6 download)
Download or read book Doppler Global Velocimetry written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-06 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 Adm Nasa
Publisher : Independently Published
ISBN 13 : 9781729330302
Total Pages : 56 pages
Book Rating : 4.3/5 (33 download)
Download or read book Doppler Global Velocimetry: Development of a Flight Research Instrumentation System for Application to Non-Intrusive Measurements of the Flow Fiel written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-10-27 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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
ISBN 13 : 9781725724419
Total Pages : 36 pages
Book Rating : 4.7/5 (244 download)
Download or read book Doppler Global Velocimetry written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-17 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 :
Publisher :
ISBN 13 :
Total Pages : 110 pages
Book Rating : 4.:/5 (317 download)
Download or read book Doppler Global Velocimetry: Development of a Flight Research Instrumentation System for Application to Non-intrusive Measurements of the Flow Field written by and published by . This book was released on 1994 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781720569329
Total Pages : 30 pages
Book Rating : 4.5/5 (693 download)
Download or read book Hardening Doppler Global Velocimetry Systems for Large Wind Tunnel Applications written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 :
Publisher :
ISBN 13 :
Total Pages : 34 pages
Book Rating : 4.:/5 (946 download)
Download or read book Accuracy and Application of Doppler Global Velocimetry to Complex Aerodynamic Flows written by and published by . This book was released on 2001 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: A two-component point Doppler velocimeter system using iodine vapor absorption cells has been improved through the use of vapor-limited cells that are insensitive to temperature variations. Also, use of a measurement volume of reduced size has improved the RMS results. Two-component velocity measurements have been obtained for a 1 inch diameter uniform circular jet flow at a nominal exit velocity of 60 m/sec, corresponding to a Reynolds number of 100,000. Similar data have also been obtained for an annular jet and a swirling jet. These data runs have been duplicated to judge the repeatability of these measurements, and also have been compared with single-component hot wire anemometer data for the same flow conditions. Mean velocity results are repeatable to within approximately 1-2 m/sec; the RMS velocity results are repeatable to within approximately 1 m/sec. Exit profiles of mean axial velocity data generally agree with hot wire anemometer results to within about 2-4 m/sec. However, the RMS velocity results are consistently 20-28% lower than the hot wire results everywhere but at the exit of the standard jet, where they are too high relative to the hot wire data. This is believed to be due to spatial averaging for the point Doppler velocimeter results, as well as to the method used to compute the RMS for some of these results. The two-component Doppler Global Velocimeter (DGV) system has also been significantly improved in the present work through the use of the same vapor-limited iodine cells that are not sensitive to temperature variations.
Author : National Aeronautics and Space Adm Nasa
Publisher : Independently Published
ISBN 13 : 9781729330098
Total Pages : 62 pages
Book Rating : 4.3/5 (3 download)
Download or read book Doppler Global Velocimeter Development for the Large Wind Tunnels at Ames Research Center written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-10-27 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 : Luther R. Gartrell
Publisher :
ISBN 13 :
Total Pages : 28 pages
Book Rating : 4.:/5 (317 download)
Download or read book Application of Laser Doppler Velocimeter to Chemical Vapor Laser System written by Luther R. Gartrell and published by . This book was released on 1993 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : United States. National Aeronautics and Space Administration
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (213 download)
Download or read book Doppler Global Velocimeter Development For The Large Wind Tunnels At Ames Research Center... NASA-TM-112210... Oct. 31, 1997 written by United States. National Aeronautics and Space Administration and published by . This book was released on 1998* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Thomas J. Beutner
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (11 download)
Download or read book Characterization and Applications of Doppler Global Velocimetry written by Thomas J. Beutner and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 190 pages
Book Rating : 4.:/5 (742 download)
Download or read book Development and Testing of the Virginia Tech Doppler Global Velocimeter written by and published by . This book was released on 2003 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Repairs and modifications were made to a flow velocity measurement system designed to measure a planar area of unsteady three component velocities in a single realization using a velocity measurement technique referred to as Doppler Global Velocimetry (DGV). Several hardware components in the system were modified and new hardware was added. Significant improvements were made to the procedures used in acquiring DGV data as well as the procedures used in reducing the acquired DGV data. Though hardware problems were - encountered successful iodine cell calibrations were acquired and attempts were made to acquire DGV velocity data from a calibration wheel and in the wake of a 6:1 prolate spheroid. These attempts were hampered by poor performance of the Nd:YAG laser and one of the digital cameras used in this research. While the magnitudes of the velocities acquired from the calibration wheel were noticeably higher than those calculated from the angular velocity and large fluctuations were present in these reduced velocities the general trends measured by the IT DGV system matched those calculated from the angular velocity: The attempt to acquire flow field data in the wake of a 6:1 prolate spheroid model was unsuccessful due to insufficient seed particle density in the area where data were to be obtained. The results of this research indicate that while significant improvements have been made to the system, there are still some significant problems to overcome.
Author : Yong Zheng
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (942 download)
Download or read book The Development of a Doppler Global Velocimeter for Whole-Field Velocity Measurement and Its Image Processing Schemes Using Single Camera written by Yong Zheng and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, the development of a Doppler Global Velocimetry (DGV) system using single high speed camera including both hardware and data reduction software is described. DGV is an emerging technique for whole field velocity measurement based upon the Doppler frequency shift of the light scattered by the seeded particles in the flow field. Determination of the Doppler shift is achieved by applying a frequency-to-intensity image conversion in the form of an Absorption Line Filter (ALF) cell containing iodine vapor inside the cell. The Doppler frequency shift of the light scattered by the moving seed particles is then employed to calculate the velocity of the moving particles. Using light sheet generated by applying a set of optics and the laser source and imaging optics, the DGV measures the global velocity of a two-dimensional section of the seeded jet flow. Based upon the DGV system first developed by C. Gaharan [1] in 1996, this study describes a simplified optical system and corresponding data reduction code developments in Matlab. A new laser light source, single lens imaging optical system and a single high speed camera (Phantom V711, Vision Research Inc.) are the main modifications on the hardware. For the previous DGV system developed by C. Gaharan [1], two separate cameras were required for simultaneously recording ALF and REF images of the flow field, while the simplified imaging optical system in this study is able to record both the ALF and REF images on the same screen, which makes applying a single camera adequate to capture the data images required for data reduction and speed calculation without having to sync the capturing operation between separate cameras. An integrated LabView code and a Matlab data reduction code were developed to perform the functions of spatial calibration, intensity calibration, ALF cell calibration, speed calibration and velocity calculation. The system is tested by measuring the surface speed across a 99.06 mm diameter white disc rotating at varied speed from 6000 rpm to 18000 rpm under selected transmission ratios of the ALF cell, as well as a 12.7mm diameter free-expansion turbulent jet operating at a primary Mach number of 0.15. In the DGV system, telecentric lens is applied between the test plane area and the imaging optical system to eliminate the image distortions on the edge area of the lens. In this study, 0.16X Techspec Silver Series Telecentric Lens and 0.06X Gold Series Telecentric Lens are respectively applied, the 0.06X telecentric allows over 6.25 times the light of 0.16X telecentric lens to be collected and recorded by the high speed Phantom camera, corresponding difference resulting from this two telecentric lens is quantified. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/155058
Author : National Aeronautics and Space Adm Nasa
Publisher : Independently Published
ISBN 13 : 9781729178720
Total Pages : 26 pages
Book Rating : 4.1/5 (787 download)
Download or read book Application of Laser Doppler Velocimeter to Chemical Vapor Laser System written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-10-24 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: A laser Doppler velocimeter (LDV) system was used to measure iodide vapor flow fields inside two different-sized tubes. Typical velocity profiles across the laser tubes were obtained with an estimated +/-1 percent bias and +/-0.3 to 0.5 percent random uncertainty in the mean values and +/-2.5 percent random uncertainty in the turbulence-intensity values. Centerline velocities and turbulence intensities for various longitudinal locations ranged from 13 to 17.5 m/sec and 6 to 20 percent, respectively. In view of these findings, the effects of turbulence should be considered for flow field modeling. The LDV system provided calibration data for pressure and mass flow systems used routinely to monitor the research laser gas flow velocity. Gartrell, Luther R. and Hunter, William W., Jr. and Lee, Ja H. and Fletcher, Mark T. and Tabibi, Bagher M. Langley Research Center RTOP 505-59-54-03...
Author : James F. Meyers
Publisher :
ISBN 13 :
Total Pages : 6 pages
Book Rating : 4.:/5 (228 download)
Download or read book Three Component Doppler Global Velocimeter Measurements of the Flow Above a Delta Wing written by James F. Meyers and published by . This book was released on 1992 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new measurement technique is being developed by NASA to measure off-surface flow fields. This method, Doppler global velocimetry, will allow qualification 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, three component velocity measurements of the vortical flow field above a thin 75 degree delta wing were made in the NASA Langley Basic Aerodynamics Research Tunnel. Measurements were made of the flow field at the 70-percent chord locations at angles-of-attack of 20.5-and 40.0-degrees to investigate unburst and burst vortices. For comparison, previous fringe-type laser velocimeter measurements of the flow field at the same conditions are included.
