Effects of Rarefaction on Hypersonic Boundary Layer Flow Over Discrete Surface Roughness

2010 ◽  
Author(s):  
Kelly Stephani ◽  
David Goldstein ◽  
Philip Varghese
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Boundary Layer Flow ◽  
Hypersonic Boundary Layer ◽  
Discrete Surface ◽  
Layer Flow

On Numerical Prediction of the Stability of Hypersonic Boundary-Layer Flow Over a Row of Microcavities

2003 ◽  
Author(s):  
Vassilios Theofilis ◽  
Michel O. Deville ◽  
Peter W. Duck ◽  
Alexander Fedorov
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Flow ◽  
Flow Instability ◽  
Viscous Sublayer ◽  
Hypersonic Boundary Layer ◽  
Two Dimensional ◽  
Flow Stabilization ◽  
Two Dimensional Flow ◽  
Dimensional Boundary ◽  
Layer Flow

This paper is concerned with the structure of steady two–dimensional flow inside the viscous sublayer in hypersonic boundary–layer flow over a flat surface in which microscopic cavities (‘microcavities’) are embedded. Such a so–called Ultra Absorptive Coating (UAC) has been predicted theoretically [1] and demonstrated experimentally [2] to stabilize passively hypersonic boundary–layer flow. In an effort to further quantify the physical mechanism leading to flow stabilization, this paper focuses on the nature of the basic flows developing in the configuration in question. Direct numerical simulations are performed, addressing firstly steady flow inside a singe microcavity, driven by a constant shear, and secondly a model of a UAC surface in which the two–dimensional boundary layer over a flat plate and a minimum nontrivial of two microcavities embedded in the wall are solved in a coupled manner. The influence of flow– and geometric parameters on the obtained solutions is illustrated. Based on the results obtained, the limitations of currently used theoretical methodologies for the description of flow instability are identified and suggestions for the improved prediction of the instability characteristics of UAC surfaces are discussed.

An instability in supersonic boundary-layer flow over a compression ramp

1995 ◽  
Vol 300 ◽  
pp. 265-285 ◽  
Author(s):  
K. W. Cassel ◽  
A. I. Ruban ◽  
J. D. A. Walker
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Flow ◽  
Streamwise Velocity ◽  
Supersonic Boundary Layer ◽  
Recirculation Region ◽  
Hypersonic Boundary Layer ◽  
Recirculating Flow ◽  
Inflection Points ◽  
Compression Ramp ◽  
Layer Flow

Separation of a supersonic boundary layer (or equivalently a hypersonic boundary layer in a region of weak global interaction) near a compression ramp is considered for moderate wall temperatures. For small ramp angles, the flow in the vicinity of the ramp is described by the classical supersonic triple-deck structure governing a local viscous-inviscid interaction. The boundary layer is known to exhibit recirculating flow near the corner once the ramp angle exceeds a certain critical value. Here it is shown that above a second and larger critical ramp angle, the boundary-layer flow develops an instability. The instability appears to be associated with the occurrence of inflection points in the streamwise velocity profiles within the recirculation region and develops as a wave packet which remains stationary near the corner and grows in amplitude with time.

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