Laminar Separation in Supersonic and Hypersonic Flows PDF Download
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Author: Jean J. Ginoux
Publisher:
ISBN:
Category : Aerodynamics, Hypersonic
Languages : en
Pages : 32
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Book Description
High speed two-dimensional reattaching flows are characterized by the development of regularly spaced vortices in the boundary layer, whose effect is to produce heat transfer rates at reattachment which are, locally over the span, considerably higher in laminar and transitional flows than in the turbulent case. These results are expected to occur both at supersonic and hypersonic speeds, as these vortices were observed over a range of Mach numbers of 1.5 to 7.0. A basic difference in the recovery of total energy at reatachment was observed between laminar and transitional flows over ramps. In the latter case, the recovery temperature was maximum at reattachment and decreased to the laminar theoretical value in a region downstream of reattachment, where the flow was turbulent. The aerodynamic heating of sweptback wings can be predicted by a simple method derived from flat plate theory and by superimposing flow components parallel and perpendicular to the leading edge. Streamwise vortices do not seem to affect the average heat transfer coefficient. (Author).
Author: Jean J. Ginoux
Publisher:
ISBN:
Category : Aerodynamics, Hypersonic
Languages : en
Pages : 32
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Book Description
High speed two-dimensional reattaching flows are characterized by the development of regularly spaced vortices in the boundary layer, whose effect is to produce heat transfer rates at reattachment which are, locally over the span, considerably higher in laminar and transitional flows than in the turbulent case. These results are expected to occur both at supersonic and hypersonic speeds, as these vortices were observed over a range of Mach numbers of 1.5 to 7.0. A basic difference in the recovery of total energy at reatachment was observed between laminar and transitional flows over ramps. In the latter case, the recovery temperature was maximum at reattachment and decreased to the laminar theoretical value in a region downstream of reattachment, where the flow was turbulent. The aerodynamic heating of sweptback wings can be predicted by a simple method derived from flat plate theory and by superimposing flow components parallel and perpendicular to the leading edge. Streamwise vortices do not seem to affect the average heat transfer coefficient. (Author).
Author: J. Don Gray
Publisher:
ISBN:
Category : Laminar boundary layer
Languages : en
Pages : 64
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Book Description
Experiments at supersonic speeds and at Mach 8 were conducted to determine the conditions which govern the extent of shock-induced laminar flow separations on axisymmetric configurations at zero yaw and without heat transfer. From an extensive correlation of surface pressure data and schlieren photographs, it is shown that the extent of reverse flow is essentially a function of the ratio of the wetted length to the flare divided by the laminar boundary thickness there. As a result, the relative extent of laminar flow separation decreases with a unit Reynolds number increase and grows through an increase in Mach number. Finally, increasing the flare angle increases the length of the reverse flow region.
Author: Paul K. Chang
Publisher: Elsevier
ISBN: 1483181286
Category : Technology & Engineering
Languages : en
Pages : 800
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Book Description
Interdisciplinary and Advanced Topics in Science and Engineering, Volume 3: Separation of Flow presents the problem of the separation of fluid flow. This book provides information covering the fields of basic physical processes, analyses, and experiments concerning flow separation. Organized into 12 chapters, this volume begins with an overview of the flow separation on the body surface as discusses in various classical examples. This text then examines the analytical and experimental results of the laminar boundary layer of steady, two-dimensional flows in the subsonic speed range. Other chapters consider the study of flow separation on the two-dimensional body, flow separation on three-dimensional body shape and particularly on bodies of revolution. This book discusses as well the analytical solutions of the unsteady flow separation. The final chapter deals with the purpose of separation flow control to raise efficiency or to enhance the performance of vehicles and fluid machineries involving various engineering applications. This book is a valuable resource for engineers.
Author: Dean R. Chapman
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 24
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Book Description
Some results are described of fundamental research conducted on various flow separation phenomena in two-dimensional streams. Experimental and theoretical results are described for the pressure rise across a reattachment region, and for the Reynolds number dependence of the pressure rise to a separation point. Observations are made throughout of the location of transition relative to reattachment and to separation, since this relative location turned out to be the dominant variable investigated.
Author: Jean-Marie Grange
Publisher:
ISBN:
Category : Aerodynamics, Hypersonic
Languages : en
Pages : 98
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Book Description
Author: C. L. W. Edwards
Publisher:
ISBN:
Category : Aerodynamics, Hypersonic
Languages : en
Pages : 36
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Book Description
Author: James Courtland Townsend
Publisher:
ISBN:
Category : Aerodynamics, Hypersonic
Languages : en
Pages : 34
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Book Description
Author: Jean J. Ginoux
Publisher:
ISBN:
Category :
Languages : en
Pages : 1
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Book Description
A study of three-dimensional flow perturbations in laminar supersonic flows was made on flat plates with sweptback leading edges and in the reattachment region of the flow over flat plates with backward-facing steps. It was shown that a cross-flow existed in the boundary layer on flat plates with supersonic sweptback leading edges of small bluntness, which increased in magnitude from the centerline towards the sides of the models. In separated flows, only an extremely small amount of cross-flow was needed to destabilize the flow and to create regular spanwise variations in total pressure. Larger cross-flows, controlled by a systematic variation of the angle of sweep either of the leading edge or of the edge of the step, had no further effect. Detailed surveys made in a reattaching laminar supersonic flow with a static probe showed that the three-dimensional perturbations that existed in the boundary layer were formed by two layers of equidistant contra-rotating streamwise vortices: one located near the wall and a second one near the outer edge of the boundary layer. (Author).
Author: Jean J. Ginoux
Publisher:
ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 56
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Book Description
The investigation is a first step to the study of the effect of cross flow in laminar separation at supersonic speeds. It is related to the selection of a final axi-symmetric model. Several problems were examined. First, the effect of streamwise vortices that develop systematically in laminar reattaching flows, triggered by small irregularities in the leading edge thickness. Second, the choice of the diameter of the model such that the flow resembles that of an equivalent planar body, third the programming of Lees-Reeves theory on a 1130 IBM computer to perform a parametric study and finally the development of a new accurate technique or criteria to ascertain that fully laminar shock wave boundary layer interactions can be obtained. (Author).
Author: Robert H. Korkegi
Publisher:
ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 60
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Book Description
The research was designed to gain understanding of the flow of air at high speeds over the components of lifting supersonic and hypersonic vehicles--wings, flaps, fins, inlets--and their interactions with respect to heating, surface friction, pressure, and aerodynamic forces. The objective was to help predict (a) flows on complex aerospace vehicle configurations in high-speed flight and (b) the location of areas of high heating. The research covers the areas of laminar and turbulent boundary layers, boundary layer transition, boundary layer separation, base flows and wakes, low density flows, three-dimensional interactions, viscous flow problems, and some flow measurement techniques.
