Fundamental Aspects of the Coupling of Non-Equilibrium Vibrational Kinetics and Dissociation-Recombination Processes with the Boundary Layer Fluidynamics in N2 and Air Hypersonic Flows

1996 ◽  
pp. 703-716 ◽  
Author(s):  
I. Armenise ◽  
M. Capitelli ◽  
C. Gorse
Keyword(s):  
Boundary Layer ◽  
Hypersonic Flows ◽  
Recombination Processes ◽  
Vibrational Kinetics ◽  
Non Equilibrium

Asymptotic defect boundary layer theory applied to thermochemical non-equilibrium hypersonic flows

1997 ◽  
Vol 339 ◽  
pp. 213-238 ◽  
Author(s):  
S. SÉROR ◽  
D. E. ZEITOUN ◽  
J.-Ph. BRAZIER ◽  
E. SCHALL
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
Wind Tunnel ◽  
Boundary Layer Theory ◽  
Hypersonic Flows ◽  
Navier Stokes ◽  
First Order ◽  
Boundary Layer Equations ◽  
Defect Boundary ◽  
Non Equilibrium

Viscous flow computations are required to predict the heat flux or the viscous drag on an hypersonic re-entry vehicle. When real gas effects are included, Navier–Stokes computations are very expensive, whereas the use of standard boundary layer approximations does not correctly account for the ‘entropy layer swallowing’ phenomenon. The purpose of this paper is to present an extension of a new boundary layer theory, called the ‘defect approach’, to two-dimensional hypersonic flows including chemical and vibrational non-equilibrium phenomena. This method ensures a smooth matching of the boundary layer with the inviscid solution in hypersonic flows with strong entropy gradients. A new set of first-order boundary layer equations has been derived, using a defect formulation in the viscous region together with a matched asymptotic expansions technique. These equations and the associated transport coefficient models as well as thermochemical models have been implemented. The prediction of the flow field around the blunt-cone wind tunnel model ELECTRE with non-equilibrium free-stream conditions has been done by solving first the inviscid flow equations and then the first-order defect boundary layer equations. The numerical simulations of the boundary layer flow were performed with catalytic and non-catalytic conditions for the chemistry and the vibrational mode. The comparison with Navier–Stokes computations shows good agreement. The wall heat flux predictions are compared to experimental measurements carried out during the MSTP campaign in the ONERA F4 wind tunnel facility. The defect approach improves the skin friction prediction in comparison with a classical boundary layer computation.

Local Thermal Non-equilibrium Analysis of Boundary Layer Flow of Carreau Fluid Over a Wedge in a Porous Medium

2021 ◽  
Author(s):  
Ramesh Kudenatti ◽  
Sandhya L
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Porous Medium ◽  
Boundary Layer Flow ◽  
Fluid Phase ◽  
Equilibrium Analysis ◽  
Local Thermal Equilibrium ◽  
Carreau Fluid ◽  
Layer Flow ◽  
Non Equilibrium

Abstract This work examines the steady two-dimensional mixed convection boundary layer flow of non-Newtonian Carreau fluid embedded in a porous medium. The impermeable wedge is at rest over which the momentum and thermal boundary layers form due to motion of Carreau fluid with a large Reynolds number. We consider local thermal non-equilibrium for which the temperature of the solid porous medium is different from that of fluid phase, and hence, a single heat-transport equation is replaced by a two-temperature model. The governed equations for flow and heat transfer are converted into a system of ordinary differential equations using a similarity approach. It is observed that local thermal non-equilibrium effects are dominant for small interphase heat transfer rate and porosity scaled conductivity parameters. It is shown that the temperature at any location of the solid porous medium is always higher than that of fluid phase. When these parameters are increased gradually the local thermal equilibrium phase is recovered at which the temperatures of the fluid and solid are identical at each pore. Similar trend is noticed for both shear-thinning and shear-thickening fluids. The results further show that heat exchange between the fluid and solid porous medium is similar to both assisted and opposed flows and Carreau fluid. The velocity and temperature fields for the various increasing fluid index, Grashof number and permeability show that the thickness of the momentum and thermal boundary layer is thinner.

Non-conventional dissociation rate in non-equilibrium boundary layer

Shock Waves ◽  
2005 ◽  
pp. 185-190
Author(s):  
N. Belouaggadia ◽  
R. Brun ◽  
T. Saito ◽  
K. Takayama
Keyword(s):  
Boundary Layer ◽  
Dissociation Rate ◽  
Non Equilibrium
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