Roughness, Bluntness, and Angle of Attack Effects on Hypersonic Boundary Layer Transition PDF Download
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Author: H. T. Nagamatsu
Publisher:
ISBN:
Category :
Languages : en
Pages : 55
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Book Description
An investigation was conducted in a hypersonic shock tunnel to study the laminar boundary layer transition on a highly cooled 10-degree cone of 4-foot length over the Mach number range of 8.5 to 10.5 with a stagnation temperature of 1400K. The effects on transition of tip surface roughness, tip bluntness, and =2-degree angle of attack were investigated. With fast response thin film surface heat transfer gauges, it was possible to detect the passage of turbulent bursts that appeared at the beginning of transition. It was found that the surface roughness greatly promoted transition in the proper Reynolds number range. The Reynolds number for the beginning and end of transition at the 8.5 Mach number location were 3,800,000 to 9,600,000 and 2,200,000 to 4,200,000 for the smooth sharp tip and rough sharp tip, respectively. The local skin friction data agreed with the heat transfer data through Reynolds analogy. The tip bluntness data showed a strong delay in the beginning of transition for a cone base to tip diameter ratio of 20, approximately a 35% increase in Reynolds number over that of the smooth sharp tip case. The angle of attack data indicated the cross flow to have a strong influence on transition by promoting it on the sheltered side of the cone and delaying it on the windward side. (Author).
Author: H. T. Nagamatsu
Publisher:
ISBN:
Category :
Languages : en
Pages : 55
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Book Description
An investigation was conducted in a hypersonic shock tunnel to study the laminar boundary layer transition on a highly cooled 10-degree cone of 4-foot length over the Mach number range of 8.5 to 10.5 with a stagnation temperature of 1400K. The effects on transition of tip surface roughness, tip bluntness, and =2-degree angle of attack were investigated. With fast response thin film surface heat transfer gauges, it was possible to detect the passage of turbulent bursts that appeared at the beginning of transition. It was found that the surface roughness greatly promoted transition in the proper Reynolds number range. The Reynolds number for the beginning and end of transition at the 8.5 Mach number location were 3,800,000 to 9,600,000 and 2,200,000 to 4,200,000 for the smooth sharp tip and rough sharp tip, respectively. The local skin friction data agreed with the heat transfer data through Reynolds analogy. The tip bluntness data showed a strong delay in the beginning of transition for a cone base to tip diameter ratio of 20, approximately a 35% increase in Reynolds number over that of the smooth sharp tip case. The angle of attack data indicated the cross flow to have a strong influence on transition by promoting it on the sheltered side of the cone and delaying it on the windward side. (Author).
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: Paul F. Holloway
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 52
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Author: Michael S. Holden
Publisher:
ISBN:
Category : Skin friction (Aerodynamics)
Languages : en
Pages : 90
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Author: P. Calvin Stainback
Publisher:
ISBN:
Category : Aerodynamics, Hypersonic
Languages : en
Pages : 82
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Author: E. R. Van Driest
Publisher:
ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 108
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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.
Author: Kenneth F. Stetson
Publisher:
ISBN:
Category : Angle of attack (Aerodynamics)
Languages : en
Pages : 98
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 248
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 84
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New hypersonic wind tunnel data have been obtained to investigate boundary layer transition, with primary emphasis given to tip bluntness and angle of attack effects. The rearward displacement of transition on the cone frustum due to tip bluntness was found to be quite sensitive to free stream Mach number as well as the entropy layer swallowing by the boundary layer. At the highest Mach number obtained in these experiments (M = 9.3), the length of laminar flow could be extended to about nine times the length of laminar flow of a sharp cone at identical conditions. The sensitivity of the maximum rearward displacement of transition with free stream Mach number appeared to be primarily related to local Reynolds number reduction because of pressure losses across the bow shock. Low transition Reynolds numbers typically found on nosetips, extended onto the front portion of the cone frustum. It appears that the still unexplained low transition Reynolds numbers associated with blunt bodies in hypersonic flow includes not only the nosetip region, but the forward portion of the cone frustum. Transition location was found to be sensitive to small changes in angle of attack, and both the sharp and blunt tips produced a rearward movement of transition on the windward ray at small angles of attack. A low supersonic flared nozzle closely duplicated the hypersonic pressure and heat transfer distributions over the nose region of a blunt body.
Author:
Publisher:
ISBN:
Category : Aerodynamics, Hypersonic
Languages : en
Pages : 28
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