Equilibrium air stagnation point boundary-layer calculations using a variable heat of dissociation model

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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A New Method for the Solution of a Differential Equation with Two-Point Boundary Conditions Applied to the Compressible Boundary Layer on a Yawed Infinite Wing

Journal of the Royal Aeronautical Society ◽

10.1017/s036839310012944x ◽

1956 ◽

Vol 60 (552) ◽

pp. 808-809

Author(s):

L. F. Crabtree ◽

E.R. Woollett

Keyword(s):

Differential Equation ◽

Boundary Layer ◽

Exact Solution ◽

Stagnation Point ◽

Close Agreement ◽

Equations Of Motion ◽

New Method ◽

Compressible Boundary Layer ◽

Point Boundary ◽

Direct Solution

The compressible laminar boundary layer on a yawed infinite wing is considered in Ref. 1, where it is shown that the problem may be solved by a direct solution of the linearised equations of motion under certain assumptions. As an example of this procedure the boundary layer near a stagnation point was calculated. Tinkler has published solutions of the exact equations for the general Falkner-Skan case (Ref. 1) obtained on the M.I.T. differential analyser for several values of the parameter involved. It has been found that the numerical results of Ref. 1 were in error and the corrected results obtained by a new method are tabulated below. Tinkler's exact solution of the stagnation point flow for ω = 0·10 is also given for comparison, and it will be seen that there is close agreement

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Heat and mass transfer in unsteady compressible axisymmetric stagnation point boundary layer flow over a rotating body

International Journal of Heat and Mass Transfer ◽

10.1016/0017-9310(82)90016-3 ◽

1982 ◽

Vol 25 (2) ◽

pp. 290-293 ◽

Cited By ~ 8

Author(s):

M. Kumari ◽

G. Nath

Keyword(s):

Boundary Layer ◽

Mass Transfer ◽

Heat And Mass Transfer ◽

Stagnation Point ◽

Boundary Layer Flow ◽

Point Boundary ◽

Rotating Body ◽

Layer Flow

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On the sensitivity of heat transfer in the stagnation-point boundary layer to free-stream vorticity

Journal of Fluid Mechanics ◽

10.1017/s0022112063000963 ◽

1963 ◽

Vol 16 (4) ◽

pp. 497-520 ◽

Cited By ~ 81

Author(s):

S. P. Sutera ◽

P. F. Maeder ◽

J. Kestin

Keyword(s):

Heat Transfer ◽

Boundary Layer ◽

Prandtl Number ◽

Stagnation Point ◽

Thermal Boundary Layer ◽

Free Stream ◽

Stokes Equations ◽

Point Boundary ◽

Oncoming Flow ◽

Flat Plates

Experiments have given evidence of strong sensitivity of the stagnation-point heat transfer on cylinders to small changes in the intensity of free-stream turbulence. A similar effect on local heat-transfer rates to flat plates has been measured, but only when a favourable pressure gradient is present. In this work it is theorized that vorticity amplification by stretching is a possible, and perhaps the dominant, underlying mechanism responsible for this sensitivity. A mathematical model is presented for a steady, basically plane stagnation flow into which is steadily transported disturbed unidirectional vorticity having the only orientation susceptible to stretching. The resulting velocity and temperature fields in the stagnation-point boundary layer are analysed assuming the fluid to be incompressible and to have constant properties. By means of iterative procedures and electronic analogue computation an approximate solution to the full Navier-Stokes equations is achieved which indicates that amplification by stretching of vorticity of sufficiently large scale can occur. Such vorticity, present in the oncoming flow with a small intensity, can appear near the boundary layer with an amplified intensity and induce substantial three-dimensional effects therein. It is found that the thermal boundary layer is much more sensitive to the induced effects than the velocity boundary layer. Computations indicate that a certain amount of distributed vorticity in the oncoming flow causes the shear stress at the wall to increase by 5%, while the heat transfer there is augmented by 26% in a fluid with a Prandtl number of 0.74. Preliminary computations reveal that the sensitivity of the thermal boundary layer increases with Prandtl number.

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