Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: G. C. Herring
Publisher: DIANE Publishing
ISBN: 1428990690
Category : Aerodynamics, Supersonic
Languages : en
Pages : 28

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Book Description
We demonstrate instantaneous flow visualization of the boundary layer region of a Mach 2.5 supersonic flow over a flat plate that is interacting with an impinging shock wave. Tests were performed in the Unitary Plan Wind Tunnel (UPWT) at NASA Langley Research Center. The technique is elastic light scattering using 10-nsec laser pulses at 532 nm. We emphasize that no seed material of any kind, including water (H2O), is purposely added to the flow. The scattered light comes from a residual impurity that normally exists in the flow medium after the air drying process. Thus, the technique described here differs from the traditional vapor-screen method, which is typically accomplished by the addition of extra H2O vapor to the airflow. The flow is visualized with a series of thin two-dimensional light sheets (oriented perpendicular to the streamwise direction) that are located at several positions downstream of the leading edge of the model. This geometry allows the direct observation of the unsteady flow structure in the spanwise dimension of the model and also allows the indirect observation of the boundary layer growth in the streamwise dimension.

Author: Edward J. Hopkins
Publisher:
ISBN:
Category : Boundary layer control
Languages : en
Pages : 28

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Author: Albert L. Braslow
Publisher:
ISBN:
Category : Numerical analysis
Languages : en
Pages : 48

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Author: Richard M. Wood
Publisher:
ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 104

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Author: Howard L. Wesoky
Publisher:
ISBN:
Category : Axial flow
Languages : en
Pages : 40

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Author: Wellington Edrington Gray
Publisher:
ISBN: 9780114702908
Category : Boundary layer
Languages : en
Pages : 6

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Author: National Aeronaut Administration (Nasa)
Publisher:
ISBN:
Category :
Languages : en
Pages : 32

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Book Description
Flow field survey results for the effect of ramp-shaped vortex generators (VG) on a turbulent boundary layer are presented. The experiments are carried out in a low-speed wind tunnel and the data are acquired primarily by hot-wire anemometry. Distributions of mean velocity and turbulent stresses as well as streamwise vorticity, on cross-sectional planes at various downstream locations, are obtained. These detailed flow field properties, including the boundary layer characteristics, are documented with the primary objective of aiding possible computational investigations. The results show that VG orientation with apex upstream, that produces a downwash directly behind it, yields a stronger pair of streamwise vortices. This is in contrast to the case with apex downstream that produces a pair of vortices of opposite sense. Thus, an array of VG s with the former orientation, usually considered for film-cooling application, may also be superior for mixing enhancement and boundary layer separation control. (See CASI ID 20120009374 for Supplemental CD-ROM.) Zaman, K. B. M. Q. and Hirt, S. M. and Bencic, T. J. Glenn Research Center NASA/TM-2012-217437, E-18130 WBS 561581.02.08.03.47.06.03 VORTEX GENERATORS; VORTICITY; TURBULENT BOUNDARY LAYER; WIND TUNNEL TESTS; BOUNDARY LAYER SEPARATION; FLOW DISTRIBUTION; VELOCITY MEASUREMENT; UPSTREAM; DOWNWASH; LOW SPEED

Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781793967527
Category : Science
Languages : en
Pages : 34

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Book Description
Flow field survey results for the effect of ramp-shaped vortex generators (VG) on a turbulent boundary layer are presented. The experiments are carried out in a low-speed wind tunnel and the data are acquired primarily by hot-wire anemometry. Distributions of mean velocity and turbulent stresses as well as streamwise vorticity, on cross-sectional planes at various downstream locations, are obtained. These detailed flow field properties, including the boundary layer characteristics, are documented with the primary objective of aiding possible computational investigations. The results show that VG orientation with apex upstream, that produces a downwash directly behind it, yields a stronger pair of streamwise vortices. This is in contrast to the case with apex downstream that produces a pair of vortices of opposite sense. Thus, an array of VG s with the former orientation, usually considered for film-cooling application, may also be superior for mixing enhancement and boundary layer separation control. (See CASI ID 20120009374 for Supplemental CD-ROM.) Zaman, K. B. M. Q. and Hirt, S. M. and Bencic, T. J. Glenn Research Center NASA/TM-2012-217437, E-18130

Author: Reazul Huq
Publisher:
ISBN:
Category : Boundary layer
Languages : en
Pages : 188

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Book Description
The report deals with one way of generating an unsteady flow past a body -- breaking the diaphragm of a shock tube. A visualization of the phenomenon within the boundary layer of such a flow was attempted by using bubbles. A method has been suggested for further work in this line. An unsteady flow was then generated using water as the flow medium in a towing tank following the principles of Ahlborn. Various improvements have led to an experiment that can visualize the details of flow within the boundary layer. The technique has been successfully applied to the case of unsteady flow past a flat plate.