An Experimental Investigation of Techniques to Suppress Edgetones from Perforated Wind Tunnel Walls
| Author | : N. Sam Dougherty (Jr.) |
| Publisher | : |
| Total Pages | : 44 |
| Release | : 1975 |
| Genre | : Resonance |
| ISBN | : |
An Experimental Investigation Of Techniques To Suppress Edgetones From Perforated Wind Tunnel Walls
Download An Experimental Investigation Of Techniques To Suppress Edgetones From Perforated Wind Tunnel Walls full books in PDF, epub, and Kindle. Read online free An Experimental Investigation Of Techniques To Suppress Edgetones From Perforated Wind Tunnel Walls ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
An Experimental Investigation of Techniques to Suppress Edgetones from Perforated Wind Tunnel Walls
| Author | : |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 1975 |
| Genre | : |
| ISBN | : |
The aerodynamic noise emitted by perforated walls in transonic wind tunnels has been under study for several years at AEDC. This report presents a summary of recent experimental tests to suppress perforated wall noise in transonic test sections. The mechanism of noise generation from perforated walls having 60-deg inclined holes is the edgetone phenomenon where the shear layer over each hole interacts with the trailing edge to produce intense tones at discrete frequencies. Noise reduction was achieved with several modified wall samples in the 6-in. tunnel at resonance conditions.
Influence of Wind Tunnel Noise on the Location of Boundary-layer Transition on a Slender Cone at Mach Numbers from 0.2 to 5.5
| Author | : N. Sam Dougherty (Jr.) |
| Publisher | : |
| Total Pages | : 252 |
| Release | : 1980 |
| Genre | : Boundary layer noise |
| ISBN | : |
A study was conducted to investigate the effects of wind tunnel test section noise on the location of boundary-layer transition. The study was carried out by conducting experiments on a slender, highly polished cone with an included angle of 10 deg. Wind tunnel test section noise was measured by microphones flush-mounted on the cone surface. In most of the experiments, boundary-layer transition was measured with a surface-mounted, traversing pitot pressure probe. The experiments were conducted in 23 different subsonic, transonic, and supersonic wind tunnels over a Mach number range from 0.2 to 5.5 and a unit Reynolds number range from 1.0 to 7.0 million per foot, the bulk of the data being obtained between 2.0 and 4.0 million per foot. The results show an influence of wind tunnel noise on boundary-layer transition for most of the wind tunnels. (Author)
Government Reports Annual Index
| Author | : |
| Publisher | : |
| Total Pages | : 882 |
| Release | : 1975 |
| Genre | : Government reports announcements & index |
| ISBN | : |
Scientific and Technical Aerospace Reports
| Author | : |
| Publisher | : |
| Total Pages | : 1004 |
| Release | : 1976 |
| Genre | : Aeronautics |
| ISBN | : |
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
A Survey of Transition Research at AEDC
| Author | : Jack D. Whitfield |
| Publisher | : |
| Total Pages | : 64 |
| Release | : 1977 |
| Genre | : Aerodynamics |
| ISBN | : |
This report presents a survey of experimental research on transition Reynolds numbers conducted in a large number of ground test facilities. Facilities surveyed included primary wind tunnels used for aerodynamic testing at subsonic, transonic, supersonic, and hypersonic conditions. Measurements have been made on cones and planar bodies, flat plates and hollow cylinders. This report traces the work using cones, which has been more extensive. The primary motivation for this research spanning nearly 20 years has been to verify the adequacy of the facilities to simulate flight conditions. This necessarily entailed the study of free-stream disturbances in wind tunnels and the role these disturbances play in altering transition Reynolds number which must be considered when scaling Reynolds-number-sensitive data. Results presented include current experimental efforts as recent as September 1976. In addition to the cited references, a bibliography of relevant publications from AEDC has been included.
Holographic Interferometry Measurements of Subsonic Turbulent Boundary Layers
| Author | : D. W. Sinclair |
| Publisher | : |
| Total Pages | : 60 |
| Release | : 1979 |
| Genre | : Aerodynamics |
| ISBN | : |
Laser holographic interferometry was applied to the measurement of density profiles of two-dimensional planar turbulent boundary layers on the wall of the Acoustic Research Tunnel (ART) at the Arnold Engineering Development Center (AEDC). Holograms were produced at Mach numbers 0.50 and 0.65 by the finite fringe, single-plate, dual-exposure method. The reconstructed image from this type of hologram contains fringes that are shifted relative to a reference fringe by an amount that is proportional to the difference in the densities at the two points. Therefore, it was possible to determine the density profiles by measuring the fringe shifts appearing in the reconstructed images. The results of two velocity-temperature relations are presented, and compared to data obtained by pitot, hot-wire, and split-film probes. A description of the experimental facility, hardware for data acquisition, data reduction methods, and a discussion of the problems encountered in the holographic interferometry technique are presented.
