Heat Transfer Across a Linearly Accelerated or Decelerated Laminar Boundary Layer

1965 ◽  
Vol 87 (3) ◽  
pp. 403-408 ◽  
Author(s):  
A. R. Bu¨yu¨ktu¨r ◽  
J. Kestin
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Laminar Boundary Layer ◽  
Free Stream ◽  
Frictional Heat ◽  
Stream Velocity ◽  
Transfer Rates ◽  
Boundary Layer Equations ◽  
Constant Coefficients ◽  
Prandtl Numbers

The paper presents solutions to the boundary-layer equations for heat-transfer rates into an accelerated and decelerated boundary layer in the presence of a linearly varying free-stream velocity. The equations are solved for the case of constant coefficients with frictional heat neglected, but over a range of Prandtl numbers.

Skin Friction and Heat Transfer for Laminar Boundary-Layer Flow With Variable Properties and Variable Free-Stream Velocity

1953 ◽  
Vol 20 (3) ◽  
pp. 415-421
Author(s):  
S. Levy ◽  
R. A. Seban
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Prandtl Number ◽  
Skin Friction ◽  
Laminar Boundary Layer ◽  
Boundary Layer Flow ◽  
Free Stream ◽  
Free Stream Velocity ◽  
Stream Velocity ◽  
Layer Flow

Abstract Numerical solutions of the momentum and energy equations are presented for particular types of laminar boundary-layer flow analogous to the Hartree “wedge flows.” Variation of the viscosity and of the thermal conductivity is considered under the circumstances of no dissipation, favorable pressure gradient, and the product of conductivity and density a constant. The solution is based on approximate representations of the velocity and temperature profiles in the boundary layer and these are of such character that the labor of calculation is minimized and the accuracy of the results preserved. The differential equations are reduced to two algebraic equations which rapidly yield the skin friction and the heat transfer in terms of the wall to free-stream temperature ratio for the desired value of Prandtl number. Numerical results are given for a range of wedge flows with gases of Prandtl number 0.70 and 1.0. These results reveal that when the free-stream velocity is variable the temperature difference between the wall and the free stream exerts a substantial effect on the velocity distribution in the boundary layer and on the skin-friction coefficient. Alternatively, the heat-transfer coefficient is not affected radically. A calculation method is presented for the determination of the heat transfer and skin friction for a flow with an arbitrary variation of velocity over an isothermal surface. This method utilizes the results of the present analysis for the variable property wedge flows.

scholarly journals The Effects of Upstream Mass Injection on Downstream Heat Transfer

1970 ◽  
Vol 92 (3) ◽  
pp. 385-392 ◽  
Author(s):  
W. R. Wolfram ◽  
W. F. Walker
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Laminar Boundary Layer ◽  
Flat Plates ◽  
Transfer Rates ◽  
Boundary Layer Equations ◽  
Mass Injection ◽  
Complete Set ◽  
Injection Region ◽  
Body Heat

The present study was performed in order to determine the effects of upstream mass injection on downstream heat transfer in a reacting laminar boundary layer. The study differs from numerous previous investigations in that no similarity assumptions have been made. The complete set of coupled reacting laminar boundary layer equations with discontinuous mass injection was solved for this problem using an integral-matrix technique. The effects of mass injection on heat transfer to both sharp and blunt-nosed isothermal flat plates were studied for a Mach 2 freestream. The amount of injection and the length of the injected region were varied for each body. Heat transfer rates were found to decrease markedly in the injected region. A sharp rise in heat transfer was found immediately downstream of the region of injection followed by an asymptotic approach to the heat transfer rates calculated for the case of no injection. An insulating effect was found to persist for a considerable distance downstream from the injection region. The distance required for this insulating effect to die out was found to depend on the length of the injection region as well as the rate of injection.

Turbulent Boundary Layer Heat Transfer Experiments: A Separate Effects Study on a Convexly Curved Wall

1983 ◽  
Vol 105 (4) ◽  
pp. 835-840 ◽  
Author(s):  
T. W. Simon ◽  
R. J. Moffat
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Free Stream ◽  
Initial Boundary ◽  
Stream Velocity ◽  
Asymptotic Condition ◽  
Secondary Effects ◽  
Initial State ◽  
Transfer Rates ◽  
Flat Wall

Measured heat transfer rates through turbulent and transitional boundary layers on an isothermal, convexly curved wall show Stanton numbers 20–50 percent below flat wall values. Recovery is slow on a flat wall downstream of the curve; after 60 cm, Stanton numbers were 15–20 percent below flat wall values. Five secondary effects were studied: (i) initial boundary layer thickness, (ii) free-stream velocity, (iii) free-stream acceleration, (iv) unheated starting length, and (v) transition. Regardless of the initial state, curvature without acceleration eventually forced the boundary layer into an asymptotic condition: StαReΔ2−1. Strong acceleration with curvature brought the exponent on ReΔ2 to −2.

On solutions of the compressible laminar boundary-layer equations and their behaviour near separation

1977 ◽  
Vol 80 (2) ◽  
pp. 279-292 ◽  
Author(s):  
T. Davies ◽  
G. Walker
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Mach Number ◽  
Skin Friction ◽  
Laminar Boundary Layer ◽  
Numerical Solutions ◽  
Free Stream ◽  
Suction Velocity ◽  
Boundary Layer Equations ◽  
Free Stream Mach Number

A numerical solution of the two-dimensional compressible laminar boundary-layer equations up to the point of separation is presented. For a particular mainstream velocity distribution it is necessary to specify the surface temperature (or the heat flux across the surface), the suction velocity, the free-stream Mach number and the viscosity-temperature relationship for a solution to be generated. The effect upon the position of separation of a hot or cold wall and of varying the free-stream Mach number is given special emphasis. The variations of the skin friction, heat transfer and various boundary-layer thicknesses for compressible flow past a circular cylinder and for flow with a linearly retarded mainstream were found. The behaviour of the solutions close to separation is investigated. Known functions which model the skin friction and heat transfer are introduced and are used to match the numerical solutions with the Buckmaster (1970) expansions.

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