Hypersonic Boundary-Layer Transition Research in the Boeing/AFOSR Mach-6 Quiet Tunnel PDF Download
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Author:
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ISBN:
Category :
Languages : en
Pages : 13
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Book Description
This grant was redirected to focus on the search for high-Reynolds-number quiet flow in the Boeing/AFOSR Mach-6 Quiet Tunnel at Purdue. Quiet flow with freestream noise levels comparable to flight requires maintaining laminar nozzle-wall boundary layers; this becomes increasingly difficult, and increasingly useful, as the Reynolds number increases. After nearly five years of shakedown, quiet flow was finally achieved to a freestream unit Reynolds number of 2.8 million per foot, in early 2006. Although this is 90% of the prefabrication design value, it is achieved only intermittently. The masimum feasible quiet-flow Reynolds number remains to be determined, along with the conditions for achieving it reliably. Nevertheless, the facility is presently the only hypersonic quiet tunnel, anywhere in the world, and affordable operating costs have been maintained.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 13
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Book Description
This grant was redirected to focus on the search for high-Reynolds-number quiet flow in the Boeing/AFOSR Mach-6 Quiet Tunnel at Purdue. Quiet flow with freestream noise levels comparable to flight requires maintaining laminar nozzle-wall boundary layers; this becomes increasingly difficult, and increasingly useful, as the Reynolds number increases. After nearly five years of shakedown, quiet flow was finally achieved to a freestream unit Reynolds number of 2.8 million per foot, in early 2006. Although this is 90% of the prefabrication design value, it is achieved only intermittently. The masimum feasible quiet-flow Reynolds number remains to be determined, along with the conditions for achieving it reliably. Nevertheless, the facility is presently the only hypersonic quiet tunnel, anywhere in the world, and affordable operating costs have been maintained.
Author: Steven P. Schneider
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ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722024642
Category :
Languages : en
Pages : 30
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Book Description
A flared-cone model under adiabatic and cooled-wall conditions was placed in a calibrated, low-disturbance Mach 6 flow and the stability of the boundary layer was investigated using a prototype constant-voltage anemometer. The results were compared with linear-stability theory predictions and good agreement was found in the prediction of second-mode frequencies and growth. In addition, the same 'N = 10' criterion used to predict boundary-layer transition in subsonic, transonic, and supersonic flows under low freestream noise conditions was found to be applicable for the hypersonic flow regime as well. Under cooled-wall conditions, a unique set of spectral data was acquired that documents the linear, nonlinear, and breakdown regions associated with the transition of hypersonic flow under low-noise conditions. Blanchard, Alan E. and Selby, Gregory V. and Wilkinson, Stephen P. Langley Research Center NCC1-180...
Author: Kenneth F. Stetson
Publisher:
ISBN:
Category : Aerodynamics, Hypersonic
Languages : en
Pages : 116
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Book Description
This is a survey paper on the subject of hypersonic boundary-layer transition. Part 1 discusses boundary-layer stability theory, hypersonic boundary-layer stability experiments, and a comparison between theory and experiment. Part 2 contains comments on how many configuration and flow parameters influence transition. Part 3 discusses some additional general aspects of transition. Part 4 discusses problems of predicting transition and comments on three prediction methods. Part 5 contains some general guidelines for prediction methodology. Keywords: Boundary layer transition, Boundary layer stability, Hypersonic boundary layers.
Author: Stephen P. Wilkinson
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ISBN:
Category :
Languages : en
Pages :
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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781724242556
Category :
Languages : en
Pages : 232
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Book Description
Hypersonic boundary layer measurements over a flared cone were conducted in a Mach 6 quiet wind tunnel at a freestream unit Reynolds number of 2.82 million/ft. This Reynolds number provided laminar-to-transitional flow over the cone model in a low-disturbance environment. Four interchangeable nose-tips, including a sharp-tip, were tested. Point measurements with a single hot-wire using a novel constant voltage anemometer were used to measure the boundary layer disturbances. Surface temperature and schlieren measurements were also conducted to characterize the transitional state of the boundary layer and to identify instability modes. Results suggest that second mode disturbances were the most unstable and scaled with the boundary layer thickness. The second mode integrated growth rates compared well with linear stability theory in the linear stability regime. The second mode is responsible for transition onset despite the existence of a second mode subharmonic. The subharmonic disturbance wavelength also scales with the boundary layer thickness. Furthermore, the existence of higher harmonics of the fundamental suggests that nonlinear disturbances are not associated with 'high' free stream disturbance levels. Nose-tip radii greater than 2.7% of the base radius completely stabilized the second mode. Lachowicz, Jason T. and Chokani, Ndaona Langley Research Center NASA-CR-198272, NAS 1.26:198272 NCC1-183; RTOP-505-59-50-02...
Author: Fang-Jenq Chen
Publisher:
ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 60
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Book Description
Author: A. J. Smits
Publisher:
ISBN:
Category : Boundary layer
Languages : en
Pages : 22
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Book Description
Author:
Publisher:
ISBN:
Category : Aerodynamics, Hypersonic
Languages : en
Pages : 52
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Book Description
Author: E. R. Van Driest
Publisher:
ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 108
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Book Description
Experiments carried out in the 12-inch supersonic wind tunnel to investigate the effect of three dimensional roughness elements (spheres) on boundary-layer transition on a 10-degree (apex angle) cone without heat transfer are described. The local Mach number for these tests was 2.71. The data show clearly that the minimum (effective) size of trip required to bring transition to its lowest Reynolds number varies power of the distance from the apex of the cone to the trip. Use of available data at other Mach numbers indicates that the Mach number influence for effective tripping is taken into account by a simple expression. Some remarks concerning the roughness variation for transition on a blunt body are made. Finally, a general criterion is introduced which gives insight to the transition phenomenon and anticipates effects of external and internal disturbances, Mach number transfer.
