Aerothermodynamics of Turbulent Spots in a Hypersonic Blunt Body Boundary Layer

2003 ◽  
Author(s):  
Abderrahmane Fiala ◽  
Richard Hillier
Keyword(s):  
Boundary Layer ◽  
Blunt Body ◽  
Turbulent Spots ◽  
Body Boundary

Roughness-induced turbulent wedges in a hypersonic blunt-body boundary layer

2014 ◽  
Vol 754 ◽  
pp. 208-231 ◽  
Author(s):  
A. Fiala ◽  
R. Hillier ◽  
D. Estruch-Samper
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Laminar Flow ◽  
Boundary Layer Thickness ◽  
Blunt Body ◽  
Roughness Element ◽  
Surface Heat ◽  
Hypersonic Boundary Layer ◽  
Element Size ◽  
Body Boundary

AbstractThis paper uses measurements of surface heat transfer to study roughness-induced turbulent wedges in a hypersonic boundary layer on a blunt cylinder. A family of wedges was produced by changing the height of an isolated roughness element, providing conditions in the following range: fully effective tripping, for the largest element, with a turbulent wedge forming immediately downstream of the element; a long wake, in length several hundred times the boundary layer thickness, leading ultimately to transition; and retention of laminar flow, for the smallest element. With appropriate element size, a fully intermittent wedge formed, comprising a clear train of turbulent spots.

Note on the Assessment of Flow Disturbances at a Blunt Body Traveling at Supersonic Speeds Owing to Flow Disturbances in Free Stream

1960 ◽  
Vol 27 (2) ◽  
pp. 223-229 ◽  
Author(s):  
M. V. Morkovin
Keyword(s):  
Boundary Layer ◽  
Blunt Body ◽  
Free Stream ◽  
Pressure Fluctuations ◽  
The Body ◽  
Normal Shock ◽  
Pressure Waves ◽  
Flow Disturbances ◽  
High Mach ◽  
Blunt Nose

For the purposes of assessing the magnitude of flow disturbances which would affect conditions on a blunt nose of a body moving at supersonic speeds, the detached shock is approximated by a purely normal shock. The disturbances downstream of the shock are expressed in terms of the “free-stream” disturbances by considering sinusoidal fluctuations. Pressure fluctuations generated by interactions of entropy-temperature disturbances with the normal shock may be considerable at high Mach numbers, but their effect on the transition of a laminar boundary layer to a turbulent one is a matter of speculation. However, conjectures that reflections of such pressure waves between the body and the shock wave might lead to high resonant amplifications are definitely disproved.

On the Momentum and Thermal Structures of Turbulent Spots in a Favorable Pressure Gradient

2005 ◽  
Vol 128 (4) ◽  
pp. 689-698 ◽  
Author(s):  
T. P. Chong ◽  
S. Zhong
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Pressure Gradient ◽  
Velocity Component ◽  
Thermal Boundary Layer ◽  
Temperature Fluctuations ◽  
Turbulent Spots ◽  
Zone Length ◽  
Favorable Pressure Gradient ◽  
The Difference

This paper represents the results from an experimental investigation of the flow physics behind the difference in the transition zone length indicated by the momentum boundary layer and thermal boundary layer parameters observed on the suction surfaces of gas turbine blades. The experiments were carried out on turbulent spots created artificially in an otherwise laminar boundary layer developing over a heated flat plate in a zero pressure gradient and a favorable pressure gradient. A specially designed miniature triple wire probe was used to measure the streamwise velocity component U, transverse velocity component V and temperature T simultaneously during the passage of the spots. In this paper, the general characteristics of the ensemble-averaged velocity and temperature perturbations, rms fluctuations, and the second moment turbulent quantities are discussed and the influence of favorable pressure gradient on these parameters is examined. When a favorable pressure gradient is present, unlike in the velocity boundary layer where significant velocity fluctuations and Reynolds shear stress occur both on the plane of symmetry and the spanwise periphery, high temperature fluctuations (and turbulent heat fluxes) are confined in the plane of symmetry. The difference in the levels of velocity/temperature fluctuations at these two locations gives an indication of the effectiveness of momentum/heat transfer across the span of the spots. The results of this study indicate that the heat transfer within a spot is inhibited more than that of the momentum transfer at the presence of a favorable pressure gradient. This phenomenon is expected to slow down the development of a transitional thermal boundary layer, leading to a longer transitional zone length indicated by the heat transfer parameters as reported in the literature.

Surface Curvature Effects on Three-Dimensional Blunt-Body Boundary Layers

AIAA Journal ◽  
1979 ◽  
Vol 17 (2) ◽  
pp. 133-134 ◽  
Author(s):  
D. L. Dwoyer ◽  
Clark H. Lewis ◽  
P. R. Gogineni
Keyword(s):  
Boundary Layers ◽  
Blunt Body ◽  
Three Dimensional ◽  
Surface Curvature ◽  
Curvature Effects ◽  
Body Boundary
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