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.

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.

Boundary Layer Calculation Including the Prediction of Transition and Curvature Effects

1989 ◽  
Author(s):  
B. Guyon ◽  
T. Arts
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Boundary Layers ◽  
Convex Surface ◽  
Turbine Blades ◽  
Operating Conditions ◽  
Detailed Knowledge ◽  
Flat Plates ◽  
Transfer Rates ◽  
Curvature Effects

The calculation of surface temperature on gas turbine blades in severe operating conditions requires a detailed knowledge of boundary layers behaviour. The prediction of laminar to turbulent transition as to existence and location, as well as the evaluation of heat transfer rates are major concerns. The program developed by SNECMA for this purpose is presented, in which models are introduced to take into account the main effects occuring on blades without film-cooling. The algorithm and discretisation scheme for boundary layer equations is Patankar and Spalding’s, with profiles initialization by Pohlhausen’s method. The turbulence and transition model, after Mc Donald and Fish, was improved in search for more stability and to have a better detection of the beginning of the transition. Adams and Johnston’s model for curvature, including propagation effects, was adapted to a transitional boundary layer. The validation tests of this program are described, which are based on numerous experimental data taken from a bibliography of tests over flat plates and blades. Other tests use heat transfer rate measurements conducted by SNECMA, together with VKI, on vanes and blades in non-rotating grids. The calculation results are further compared to the STAN5 program results; they show a superiority in predicting the transfer rates on a convex surface and for transitional boundary layers.

Laminar Boundary∼Layer Free Convection along an Inclined, Isothermal Surface

1972 ◽  
Vol 1 (4) ◽  
pp. 189-196 ◽  
Author(s):  
J.B. Lee ◽  
G.S.H. Lock
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Free Convection ◽  
Laminar Boundary Layer ◽  
Theoretical Consideration ◽  
Plane Surface ◽  
Convection Flow ◽  
Inclined Plane ◽  
Free Convection Flow ◽  
Boundary Layer Equations

This paper gives theoretical consideration to the problem of laminar, boundary-layer, free convection flow along a long, inclined, plane surface heated isothermally. Development of the appropriate boundary-layer equations is followed by their numerical solution for air. The effects of inclination and position on heat transfer and the temperature, pressure and velocity profiles are presented graphically for RaL ≤ 106.

A note on expansions for the two-dimensional, compressible, laminar boundary layer equations near a point of zero skin friction

1983 ◽  
Vol 94 (1-2) ◽  
pp. 93-96 ◽  
Author(s):  
G. Wilks
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Skin Friction ◽  
Laminar Boundary Layer ◽  
Two Dimensional ◽  
Transfer Coefficients ◽  
Boundary Layer Equations ◽  
Heat Transfer Coefficients

SynopsisThe first non-arbitrary coefficient, α12, of the Buckmaster expansions is evaluated in the context of the extended Goldstein-Stewartson theory. Leading terms of the next order contributions to the skin friction and heat transfer coefficients are also obtained.

An Analytical Study of Laminar Film Condensation: Part 1—Flat Plates

1961 ◽  
Vol 83 (1) ◽  
pp. 48-54 ◽  
Author(s):  
Michael Ming Chen
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Velocity Gradient ◽  
Film Condensation ◽  
Transfer Coefficients ◽  
Flat Plates ◽  
Integral Boundary ◽  
Boundary Layer Equations ◽  
Laminar Film ◽  
Laminar Film Condensation

The boundary-layer equations of momentum and energy are written in a modified integral form and solved for the case of laminar film condensation along a vertical flat plate. The analysis differs from previous works by employing the more realistic boundary condition of stationary vapor at large distances instead of zero velocity gradient at the interface. Solutions for both the liquid film and vapor boundary layer are given for the case μvρv ≪ μρ. Velocity and temperature profiles are obtained using perturbation method and the modified integral boundary-layer equations. The results show a significant negative velocity gradient at the interface as a result of vapor drag except for small values of kΔt/μλ. Theoretical heat-transfer coefficients are computed and found to be lower than previous theories, especially for low Prandtl numbers. Comparison with experimental heat-transfer data is given. The heat-transfer results are also presented in the form of an approximate formula for ease of application.

Heat transfer and transition to turbulence in the shock-induced boundary layer on a semi-infinite flat plate

1969 ◽  
Vol 36 (1) ◽  
pp. 87-112 ◽  
Author(s):  
W. R. Davies ◽  
L. Bernstein
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Flat Plate ◽  
Turbulent Flows ◽  
Laminar Boundary Layer ◽  
Flow Characteristics ◽  
Transition To Turbulence ◽  
Unsteady Boundary Layer ◽  
Transfer Rates ◽  
Laminar And Turbulent Flows

The results of experiments designed to investigate the shock-induced boundary layer on a semi-infinite flat plate are described.Those for the laminar boundary layer are shown to be in agreement with a theory due to Lam & Crocco (1958) which describes two distinct domains, one near the shock where the flow is quasi-steady in a shock-fixed co-ordinate system and an unsteady region in which the flow characteristics approach the familiar steady state asymptotically. Experimental results are also presented for the non-laminar boundary layer. In particular the transition to turbulence in this unsteady boundary layer is discussed in some detail.‘Establishment times’ for steady boundary layers are given for both laminar and turbulent flows, and their relevance to the testing times available in shock tubes is discussed. The measured heat transfer rates are compared with existing theories.

Aerothermal Boundary Layer Computation Including Strong Viscous-Inviscid Flow Interaction

1990 ◽  
Author(s):  
P. Kulisa ◽  
F. Leboeuf ◽  
P. Klinger ◽  
J. Bernard
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Film Cooling ◽  
Turbine Blades ◽  
Flow Characteristics ◽  
Inviscid Flow ◽  
Advanced Materials ◽  
Pressure Gradients ◽  
Flat Plates ◽  
Boundary Layer Equations

The high temperature level reached at the exit of combustion chambers of modern aircraft engines and the practical limitations of advanced materials, demand efficient cooling of turbine blades. Optimization of the cooling requires an accurate prediction of aerodynamic losses and heat transfer on turbine blades. A new two-dimensional compressible, aerothermal boundary layer code has been developed. The formulation includes strong viscous-inviscid interaction, which enhances the stability properties of the code. The boundary layer equations associated with the energy equation are solved with an implicit Keller-box scheme. Viscous-inviscid flow coupling is performed by adding an interaction equation which has an elliptic character. The complete system of equations is solved by a multi-pass procedure. This technique contributes to the stabilization of the method and allows the computation of regions with strong adverse pressure gradients, separation bubbles and injections in case of film cooling. Comparisons between experimental and theoretical results are provided. Flow characteristics including heat transfer were computed for several cases such as flat plates with strong pressure gradients, and turbine blade boundary layers. Good agreement between computation and experiment is observed, demonstrating the high accuracy and robustness of the code.

scholarly journals Forced convection heat transfer of Casson fluid in non-Darcy porous media

2019 ◽  
Vol 11 (1) ◽  
pp. 168781401881990 ◽  
Author(s):  
Bashar R Qawasmeh ◽  
Mohammad Alrbai ◽  
Sameer Al-Dahidi
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Porous Media ◽  
Prandtl Number ◽  
Forced Convection ◽  
Local Heat Transfer ◽  
Casson Fluid ◽  
Local Skin ◽  
Transfer Rates ◽  
Boundary Layer Equations

Forced convection of non-Newtonian Casson fluid laminar boundary layer flow past an isothermal horizontal flat plate in non-Darcy porous media is studied using Darcy–Forchheimer–Brinkman model. Similarity variables are used to transform the boundary layer equations. The boundary layer equations are reduced into system of first-order differential equations using similarity method. Then, solved numerically using adaptive Runge–Kutta–Fehlberg scheme simultaneously with shooting technique. The effects of Casson parameter, porosity, first- and second-order porous resistances, and Prandtl number on the fluid flow and heat transfer are investigated in terms of the local skin friction and local heat transfer parameters. In addition, velocity and temperature boundary layer profiles are plotted for all considered parameters. It is found that the heat transfer could be enhanced by increasing the Casson parameter and the porous resistance terms. To the contrary, the increase in the porosity reduces heat transfer rates. Finally, the increase in the Prandtl number enhances the heat transfer rates.

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