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).

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

ISBN-13:

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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).

Laser Velocimeter Optical Traverse Scheme: An Investigation of a Proposed Optical Scanning Technique for Arnold Engineering and Development Center's Four-Foot Transonic Wind Tunnel
Laser Velocimeter Optical Traverse Scheme: An Investigation of a Proposed Optical Scanning Technique for Arnold Engineering and Development Center's Four-Foot Transonic Wind Tunnel

Author: G. S. Krajci

Publisher:

Published: 1983

Total Pages: 141

ISBN-13:

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This investigation analyzed a nonstandard laser velocimeter setup proposed for use in AEDC Wind Tunnel 4T. The setup uses a gimballed mirror to move the probe volume from point to point, and the translation of a lens to control the distance in the tunnel the probe volume reaches. Results show that for equal indices of refraction inside and outside the tunnel, the laser beams of a converging pair do not totally converge with its associated beam except under certain conditions, and the probe volumes created by each pair of overlapping laser beams do not always coincide. This work then provides the conditions necessary for total convergence of a pair of laser beams for this setup. A solution is then proposed to insure convergence of each laser beam pair and overlap of the two probe volumes. More than a solution to the above problems, a method is given to determine the azimuth and elevation angles for a mirror such that the reflected beam off the mirror passes through a given point in the tunnel after traversing a window. To carry out these investigations, a computer code was written to simulate the nonstandard laser velocimeter setup, and a second code was written to determine the azimuth and elevation angles for a mirror such that the reflected beam off the mirror passes through a given point in the tunnel after traversing a window. Both codes were written in FORTRAN 77, implemented on a CDC 6000-CYBER 74.

The Use of a Laser Doppler Velocimeter in Supersonic Flow
The Use of a Laser Doppler Velocimeter in Supersonic Flow

Author: William Joseph Yanta

Publisher:

Published: 1971

Total Pages: 64

ISBN-13:

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Results are presented for an experimental program which investigated the application of an LDV technique in supersonic flows. This paper presents an analysis of the behavior of light-scattering particles in rapidly accelerating or shock decelerated flows, an evaluation of particle production techniques and the results of several velocity measurements. Measurements included the velocity distribution along the nozzle centerline and flow over a diamond airfoil in a Mach 3 tunnel and velocity profiles for a turbulent boundary layer in a Mach 4.8 facility. It is demonstrated that LDV measurements can be made consistently with errors of less than five percent if the particle lag is considered. (Author).

Transonic Wing/store Flow-field Measurement Using a Laser Velocimeter
Transonic Wing/store Flow-field Measurement Using a Laser Velocimeter

Author: F. L. Heltsley

Publisher:

Published: 1981

Total Pages: 62

ISBN-13:

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A test was conducted in the Arnold Engineering Development Center (AEDC) Aerodynamic Wind Tunnel (1T) of the Propulsion Wind Tunnel Facility (PWT) to measure the flow fields about several wing/pylon/store configurations. Test models included a wall-mounted swept wing, five-percent MK-83 and M-117 stores, and swept and unswept pylons. Flow-field velocity measurements, made by using a three-component laser velocimeter, are presented. (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

ISBN-13:

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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).