Velocity Measurements in the AEDC Low Speed Wind Tunnel (V/STOL) Using a Laser Doppler Velocimeter
Velocity Measurements in the AEDC Low Speed Wind Tunnel (V/STOL) Using a Laser Doppler Velocimeter

Author: F. H. Smith

Publisher:

Published: 1970

Total Pages: 28

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An in-house developed laser Doppler velocimeter (LDV) was used to make velocity measurements in a low speed wind tunnel. The installation and instrumentation are discussed, and velocity profiles obtained with the LDV are compared with those obtained using conventional techniques. A discussion on the factors which affect the accuracy of the LDV and improvements that would be desirable are also included. (Author).

Development of a Laser Velocimeter to be Used in AEDC Wind Tunnels
Development of a Laser Velocimeter to be Used in AEDC Wind Tunnels

Author: A. E. Lennert

Publisher:

Published: 1970

Total Pages: 201

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The report summarizes a three-year analytical and experimental program to develop a laser Doppler velocity (LDV) instrument for measuring velocities of flowing fluids. The electro-optical instruments are being developed for enhancing the measuring capabilities in the AEDC wind tunnels. The basic design parameters of the input-aligned optics LDV system and, in particular, the development of a self-aligning system to obviate the basic problems inherent with previously conceived systems, are described in detail. The design and the progress are presented on a direct readout system to determine directly three orthogonal components of velocity. A number of significant proof-of-principle experiments covering a wide variety of flows, both liquid and gaseous, are discussed. Included are the results of a V/STOL wind tunnel calibration study verifying the superior performance of the LDV for velocity determinations and boundary-layer measurements. (Author).

Turbulence Measurements with a Laser Doppler Velocimeter
Turbulence Measurements with a Laser Doppler Velocimeter

Author: William Joseph Yanta

Publisher:

Published: 1973

Total Pages: 104

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Turbulence measurements with a Laser Doppler Velocimeter (LDV) using the dual scatter or differential Doppler mode have been made in a subsonic, fully developed channel flow. The measurements were made using only those light scattering particles occurring naturally in air. Results include mean velocity profiles, turbulence intensities, Reynolds stress distributions and a skewness measurement of the velocity distribution function across the channel. Statistical techniques were used to obtain the various turbulence parameters. Guidelines have been established for the amount of data needed to obtain results with a specified accuracy and confidence level. Measurements have also been made to determine the particle-size distribution. An aerodynamic means was used to determine the size distribution, in contrast to the usual optical procedures. (Modified author abstract).

Aeronautical Engineering
Aeronautical Engineering

Author:

Publisher:

Published: 1971

Total Pages: 580

ISBN-13:

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A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in Scientific and technical aerospace reports (STAR) and International aerospace abstracts (IAA)

Design and Evaluation of a Laser Doppler Velocimeter for the AEDC-PWT 4-Foot Transonic Tunnel
Design and Evaluation of a Laser Doppler Velocimeter for the AEDC-PWT 4-Foot Transonic Tunnel

Author: F. L. Crosswy

Publisher:

Published: 1978

Total Pages: 62

ISBN-13:

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The design details and initial performance evaluation of a two-component Laser Doppler Velocimeter (LDV) system for a large transonic wind tunnel are presented. The two-color, backscatter LDV was specially developed for free-stream, pitch plane flow angle and velocity magnitude measurements using only intrinsic particulate matter as light scatterers. An environmental control system and remote optical alignment techniques were developed since the LDV was located in the hostile environment (vibration, vacuum, inaccessibility, etc.) of the tunnel plenum region. A new-type LDV signal processor was developed to process the low-level signals produced by the small intrinsic particles. A versatile, computer-based system was developed for high-speed data acquisition. LDV mean velocity and flow angle data are compared to free-stream velocity data and aerodynamic flow angle probe data. (Author).

Laser Technology in Aerodynamic Measurements
Laser Technology in Aerodynamic Measurements

Author: North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development

Publisher:

Published: 1972

Total Pages: 264

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;Contents: An introduction to the laser; Principles of holography; Mathematical methods in coherent optical systems analysis; Effects of coherence on flow visualization methods; Aerodynamic holography; Experimental holography; Characteristics of dielectric holograms; Applications of pulsed laser holography; Laser beam probing for aerodynamic flow field analysis; The laser in high speed photography; Laser metrology; Application of duel scatter laser doppler velocimeters for wind tunnel measurements.