Expansion Effects on Supersonic Turbulent Boundary Layers PDF Download
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Author:
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ISBN:
Category :
Languages : en
Pages : 191
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Book Description
The effects of various expansion regions on the large scale structure of a Mach 3 fully-developed-turbulent boundary layer are investigated. Five cases are studied: 7 deg and 14 deg centered expansions, 7 deg and 14 deg gradual expansions, and the flat plate. Multi-point surface pressure measurements, filtered Rayleigh scattering visualizations, and double-pulse visualizations were employed. Plan view images of the flat plate boundary layer reveal the presence of structures of a very large streamwise, and limited spanwise, extent. These structures were found well above the inner layer, nominally at n/delta = 0.5-1.0. The structures were also found in the expanded boundary layers. Across the expansion, the large scale structures of the outer layer undergo an increase in scale and structure angle. The small scale turbulent motions of the incoming boundary layer are quenched by the expansion, while the large scale structures respond more gradually. Convection velocities from the pressure correlations are reasonable in the incoming boundary layer, but unreasonably high in the expanded boundary layers. Convection velocities from correlations of double-pulse images appear reasonable. The discrepancy between the two results suggests the relationship between the large scale structures and the convecting pressure field is severely altered by the expansions.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 191
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Book Description
The effects of various expansion regions on the large scale structure of a Mach 3 fully-developed-turbulent boundary layer are investigated. Five cases are studied: 7 deg and 14 deg centered expansions, 7 deg and 14 deg gradual expansions, and the flat plate. Multi-point surface pressure measurements, filtered Rayleigh scattering visualizations, and double-pulse visualizations were employed. Plan view images of the flat plate boundary layer reveal the presence of structures of a very large streamwise, and limited spanwise, extent. These structures were found well above the inner layer, nominally at n/delta = 0.5-1.0. The structures were also found in the expanded boundary layers. Across the expansion, the large scale structures of the outer layer undergo an increase in scale and structure angle. The small scale turbulent motions of the incoming boundary layer are quenched by the expansion, while the large scale structures respond more gradually. Convection velocities from the pressure correlations are reasonable in the incoming boundary layer, but unreasonably high in the expanded boundary layers. Convection velocities from correlations of double-pulse images appear reasonable. The discrepancy between the two results suggests the relationship between the large scale structures and the convecting pressure field is severely altered by the expansions.
Author: Stephen Andrew Arnette
Publisher:
ISBN:
Category :
Languages : en
Pages : 774
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 129
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Book Description
A fully-developed high Reynolds number Mach 3 turbulent boundary layer and the effects of four expansion regions (centered and gradual expansions of 7 deg and 14 deg) on the boundary layer were investigated by utilizing 1) multi-point instantaneous surface pressure measurements, 2) instantaneous single- and double-pulse flow visualizations based on Filtered Rayleigh Scattering (FRS), 3) two-component planar velocity measurements using Filtered Planar Velocimetry (FPV), and 4) detailed turbulence measurements using Laser Doppler Velocimetry (LDV). Flow visualization results indicate that the upper half of the fully developed turbulent boundary layer is populated with elongated longitudinal structures of considerable streamwise but very limited spanwise extent. These structures are randomly distributed in space and time and survive even the 14 deg centered expansion. The visualizations also show that large scale structures increase both in size and angle and small scale structures are quenched across the expansions. The angle of large scale structures return to the flat plate value further downstream of the expansions. The normalized power spectra of pressure fluctuations downstream of the expansions are more concentrated at lower frequencies than their upstream counterparts, confirming the small scale quenching shown by flow visualizations.
Author: Harry Edward Bailey
Publisher:
ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 54
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Author: Maurice Tucker
Publisher:
ISBN:
Category : Air flow
Languages : en
Pages : 86
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Book Description
As an application of the method, the contour correction of supersonic nozzles for the effects of boundary-layer development is discussed from the requirement of continuity of mass flow and from the requirement of expansion- and shock-wave elimination.
Author: Jonathan A. Dawson
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Category :
Languages : en
Pages :
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Author: Leonard Paul Hampton
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ISBN:
Category :
Languages : en
Pages : 184
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Author: Jonathan Adam Dawson
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ISBN:
Category :
Languages : en
Pages : 416
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Author: P. H. Oosthuizen
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ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 41
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Book Description
A theoretical study of the effects of the wall boundary layer on the supersonic flow around a sharp convex corner is presented. Fundamentally different methods of analysis are adopted for laminar and for turbulent boundary layers. In the case of interactions involving laminar boundary layers, an analysis based on the use of classical boundary layer theory is used. Results of numerical calculations carried out using this analysis to predict the effects of the major governing parameters are presented. In all cases, a considerable upstream and downstream influence is predicted. A simplified form of this analysis, closely related to that of Curle, is also presented, this analysis leading to a simple set of explicit equations describing the flow quantities in the interaction region. Comparison of the simplified analysis with results obtained from the full analysis indicated, as is to be expected, that the simplified analysis will only give acceptable results for small expansion angles and moderate Mach numbers. In the case of turbulent boundary layer interactions, an analysis based on the assumption that there is no upstream influence and that the major portion of the expansion occurs in an effectively inviscid manner is adopted, the flow properties being calculated by the method of rotational characteristics. (Author).
Author: Maurice Tucker
Publisher:
ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 30
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Book Description
An analytical method is presented for obtaining turbulent temperature recovery factors for a thermally insulated surface in supersonic flow. The method is an extension of Squire's analysis for incompressible flow. The boundary layer velocity profile is represented by a power law and a similarity is postulated for squared-velocity the static-temperature-difference profiles.
