scholarly journals Effect of injection strategy and mainstream combustion on skin friction reduction through boundary layer combustion in scramjet combustors

2016 ◽  
Author(s):  
Tien Ken Kevin Ngo
Keyword(s):  
Boundary Layer ◽  
Skin Friction ◽  
Friction Reduction ◽  
Injection Strategy ◽  
Skin Friction Reduction ◽  
Scramjet Combustors

Application of Air Microblowing Through a Porous Wall for Skin Friction Reduction on a Flat Plate

2010 ◽  
Vol 5 (3) ◽  
pp. 38-46
Author(s):  
Vladimir I. Kornilov ◽  
Andrey V. Boiko
Keyword(s):  
Boundary Layer ◽  
Flat Plate ◽  
Skin Friction ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Porous Wall ◽  
Friction Reduction ◽  
Local Skin ◽  
Skin Friction Reduction

The effect of air microblowing through a porous wall on the properties of a turbulent boundary layer formed on a flat plate in an incompressible flow is studied experimentally. The Reynolds number based on the momentum thickness of the boundary layer in front of the porous insert is 3 900. The mass flow rate of the blowing air per unit area was varied within Q = 0−0.0488 кg/s/m2 . A consistent decrease in local skin friction, reaching up to 45−47 %, is observed to occur at the maximal blowing air mass flow rate studied.

Numerical Investigations Into the Mechanisms of Microbubble Drag Reduction

1985 ◽  
Vol 107 (3) ◽  
pp. 370-377 ◽  
Author(s):  
N. K. Madavan ◽  
C. L. Merkle ◽  
S. Deutsch
Keyword(s):  
Boundary Layer ◽  
Skin Friction ◽  
Peak Concentration ◽  
Friction Reduction ◽  
Initial Attempt ◽  
Numerical Investigations ◽  
Order Of Magnitude ◽  
Parametric Studies ◽  
Skin Friction Reduction ◽  
Layer Peak

Computational results of an initial attempt to model the phenomenon of skin-friction reduction by microbubble injection are presented. A well-tested boundary-layer code employing a simple mixing length model for the turbulence is used. The action of the bubbles is simulated by allowing the viscosity and density to vary locally as a function of a prescribed bubble concentration profile. Parametric studies of bubble location in the boundary layer, peak concentration and mixture viscosity model are performed. The order of magnitude and trends of the experimental skin-friction reduction are reproduced quite well by this simple model.

Bibliography on Skin Friction Reduction With Polymers and Other Boundary-Layer Additives

1995 ◽  
Vol 48 (7) ◽  
pp. 351-460 ◽  
Author(s):  
Richard H. Nadolink ◽  
Wayne W. Haigh
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Fluid Mechanics ◽  
Momentum Transfer ◽  
Skin Friction ◽  
Heat And Mass Transfer ◽  
Turbulent Flows ◽  
Laminar Flows ◽  
Friction Reduction ◽  
Skin Friction Reduction

This bibliography on skin friction reduction with boundary-layer additives including polymers, surfactants, disoaps, micelles, and particulates, covers over a seventy-year period from 1922 through 1994. Although the emphasis in this bibliography is on the fluid mechanics associated with alterations in boundary-layer momentum transfer, complementary studies on boundary-layer heat and mass transfer are also inlcuded. The emphasis in this bibliography is on turbulent flows for a wide variety of configurations and conditions, however, some publications on transitional and laminar flows have also been included for completeness. Over 4,900 publications are included in this sizable bibliography.

Hypervelocity Skin-Friction Reduction by Boundary-Layer Combustion of Hydrogen

2000 ◽  
Vol 37 (6) ◽  
pp. 740-746 ◽  
Author(s):  
C. P. Goyne ◽  
R. J. Stalker ◽  
A. Paull ◽  
C. P. Brescianini
Keyword(s):  
Boundary Layer ◽  
Skin Friction ◽  
Friction Reduction ◽  
Skin Friction Reduction ◽  
Combustion Of Hydrogen

Flat-Plate Skin Friction Under The Conditions Of Air Blowing Through A Wall With Intermittent In Length Permeability

2015 ◽  
Vol 10 (3) ◽  
pp. 48-62
Author(s):  
Vladimir Kornilov ◽  
Andrey Boiko ◽  
Ivan Kavun
Keyword(s):  
Boundary Layer ◽  
Flat Plate ◽  
Skin Friction ◽  
Unit Area ◽  
Friction Reduction ◽  
Local Skin ◽  
Air Blowing ◽  
Local Skin Friction ◽  
Incompressible Boundary ◽  
Skin Friction Reduction

Possibility of turbulent skin-friction reduction in an incompressible boundary layer of a flat plate with air blowing through a microperforated surface consisting of alternating permeable and impermeable sections was studied experimentally and computationally. The mass flow rate of the air per unit area was varied in the range from 0 to 0.0709 kg/s/m2 , which corresponds to the maximum blowing coefficient equal to 0.00344. A consistent reduction of the local skin-friction values along the chord of the microperforated insert was found, the reduction achieving nearly 70 % at the end of the last active blowing sections, except the impermeable surface sections demonstrating, on the contrary, the skin friction increase: the longer section, the higher skin friction.

Towards a Greater Understanding of Turbulent Skin-Friction Reduction

2002 ◽  
Author(s):  
Nick Hutchins ◽  
Kwing-So Choi
Keyword(s):  
Boundary Layer ◽  
Skin Friction ◽  
Outer Layer ◽  
Large Scale ◽  
Convection Velocity ◽  
Friction Reduction ◽  
Horseshoe Vortices ◽  
Layer Region ◽  
Skin Friction Reduction ◽  
Near Wall

Measurements have been made in a turbulent boundary layer modified by flow aligned vertical (sub-boundary layer) elements. Comparisons between the coherent structure (near-wall and outer-layer region) for both modified and canonical cases have been conducted in order to better understand the mechanism of skin friction reduction. Thus far we can report a modified near-wall convection velocity obeying inner scaling and a reduced spread of correlated events away from the wall. The outer-layer appears to be characterised by large-scale arch-like structures which produce a velocity field consistent with the heads of lifted near-wall horseshoe vortices. The modified case shows reduced convection velocity, increased frequency of occurrence and increased entrainment for this type of outer-layer event.

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