Evaluation of the Stagnation-Point Velocity Gradient in Low-Enthalpy Hypersonic Flows

2017 ◽  
Author(s):  
Zdenek Ilich ◽  
Guillaume Grossir ◽  
Olivier Chazot
Keyword(s):  
Stagnation Point ◽  
Velocity Gradient ◽  
Hypersonic Flows ◽  
Point Velocity

An Empirical Formula for Stagnation Point Velocity Gradient for Spheres and Circular Cylinders in Hypersonic Flow

1965 ◽  
Vol 69 (654) ◽  
pp. 407-408 ◽  
Author(s):  
D. R. Topham
Keyword(s):  
Stagnation Point ◽  
Velocity Gradient ◽  
Stream Flow ◽  
Free Stream ◽  
Circular Cylinders ◽  
Stream Velocity ◽  
Flow Properties ◽  
Transfer Rates ◽  
Point Velocity ◽  
Image Position

When stagnation heat transfer rates are expressed in terms of free stream flow properties, the following combination of terms is found to occur: —where ps pressure at the stagnation pointp∞free stream pressureU∞free stream velocityDnose diameterßstagnation point velocity gradient.

Mass transfer between a plane surface and an impinging turbulent jet: the influence of surface-pressure fluctuations

1982 ◽  
Vol 119 ◽  
pp. 91-105 ◽  
Author(s):  
K. Kataoka ◽  
Y. Kamiyama ◽  
S. Hashimoto ◽  
T. Komai
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Flat Plate ◽  
Stagnation Point ◽  
Surface Pressure ◽  
Velocity Gradient ◽  
Large Scale ◽  
Pressure Fluctuations ◽  
Wall Region ◽  
Local Measurement

Local measurement of the mass-transfer rate and velocity gradient when an axisymmetric jet impinges on a flat plate was carried out using an electrochemical technique. Local measurement of the surface pressure on the flat plate was carried out separately using piezoelectric pressure transducers. The stagnation-point mass-transfer coefficient reaches a maximum when the flat plate is placed at 6 nozzle diameters from a convergent nozzle. It has been confirmed that the mass transfer to the flat plate for a high Schmidt number is greatly enhanced owing to the velocity-gradient disturbances in the wall region of the boundary layer, while the momentum transfer is insensitive to such disturbances. The relative intensity of the velocity-gradient fluctuations on the wall has an extremely large value at and near to the stagnation point, and decreases downstream, approaching a large constant value.These velocity-gradient disturbances are not due to the usual interaction of Reynolds stress with the shear stress of the mean flow, but are due to the interaction with the surface-pressure fluctuations converted from the velocity fluctuations of the oncoming jet.The three co-ordinate dimensions of large-scale eddies are calculated from the auto- and spatial correlations of the surface-pressure fluctuations. It is considered that such large-scale eddies play an important role in the production of a velocity-gradient disturbance in the wall region of the boundary layer from the velocity turbulence of the approaching jet.

Stagnation-point velocity gradients for spherical segments in hypersonic flow

AIAA Journal ◽  
1969 ◽  
Vol 7 (10) ◽  
pp. 2040-2041 ◽  
Author(s):  
LARRY L. TRIMMER ◽  
EDWARD L. CLARK
Keyword(s):  
Hypersonic Flow ◽  
Stagnation Point ◽  
Velocity Gradients ◽  
Point Velocity

Transient Extinction of Counter flow Diffusion Flame

1982 ◽  
Vol 24 (3) ◽  
pp. 113-117 ◽  
Author(s):  
T. Saitoh ◽  
S. Ishiguro
Keyword(s):  
Boundary Layer ◽  
Stagnation Point ◽  
Diffusion Flame ◽  
Transient Analysis ◽  
Linear Time ◽  
Point Boundary ◽  
Boundary Layer Flows ◽  
Counter Flow ◽  
Acceleration And Deceleration ◽  
Point Velocity

A transient analysis was performed for extinction of the counter flow diffusion flame utilizing the assumptions of inviscid, incompressible, and laminar stagnation-point boundary layer flows. The unsteadiness was induced via linear time variation of the stagnation point velocity gradient. The physical meaning of the middle solution of the quasi-steady theory was clarified. The effects of acceleration and deceleration of the flow were examined and it was found that strong acceleration tends to support the flame up to a small Damkohler number, which implies that the flame strength becomes large for flames under acceleration.

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