scholarly journals HEAT TRANSFER IN A TURBULENT BOUNDARY LAYER WITH A PRESSURE GRADIENT NORMAL TO THE FLOW.

1967 ◽  
Author(s):  
H. Thomann
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Gradient

scholarly journals HEAT TRANSFER IN GRADIENT TURBULENT BOUNDARY LAYER

2019 ◽  
Vol 41 (4) ◽  
pp. 19-26
Author(s):  
A.A. Avramenko ◽  
M.M. Kovetskaya ◽  
E.A. Kondratieva ◽  
T.V. Sorokina
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Transfer Coefficient ◽  
Turbulent Boundary Layer ◽  
Pressure Gradient ◽  
Transfer Coefficient ◽  
Boundary Layer Separation ◽  
Variable Pressure ◽  
Flow Acceleration ◽  
Longitudinal Pressure Gradient

Effect of pressure gradient on heat transfer in turbulent boundary layer is constantly investigated during creation and improvement of heat exchange equipment for energy, aerospace, chemical and biological systems. The paper deals with problem of steady flow and heat  transfer in turbulent boundary layer with variable pressure in longitudinal direction. The mathematical model is presented and the analytical solution of heat transfer in the turbulent boundary layer problem at positive and negative pressure gradients is given. Dependences for temperature profiles and coefficient of heat transfer on flow parameters were obtained.  At negative longitudinal pressure gradient (flow acceleration) heat transfer coefficient can both increase and decrease. At beginning of acceleration zone, when laminarization effects are negligible, heat transfer coefficient increases. Then, as the flow laminarization increases, heat transfer coefficient decreases. This is caused by flow of turbulent energy transfers to accelerating flow. In case of positive longitudinal pressure gradient, temperature profile gradient near wall decreases. It is because of decreasing velocity gradient before zone of possible boundary layer separation.

“Rough Surface Turbulent Boundary Layer Heat Transfer Using Generalized Reynolds Analogies”

2020 ◽  
Author(s):  
James Sucec
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Gradient ◽  
Boundary Layer Flow ◽  
External Boundary ◽  
Duct Flow ◽  
Layer Flow ◽  
Predicted Values

Abstract Stanton number, St, calculations as a function of position, x, are made for turbulent, external boundary layer flow over aerodynamically rough surfaces and also for a fully developed duct flow with rough top and bottom surfaces. This is accomplished with three different forms of generalized Reynolds analogies from the literature and also with a new data correlation developed with the aid of the thermal inner and outer layers. Comparison of these predicted values of St with experimental data, from the literature, is made for several favorable equilibrium, one non-equilibrium, and a zero pressure gradient as well as a duct flow over “real” roughness patterns. Predictions compare reasonably well with the data for some of the generalized Reynolds analogies.

Heat Transfer in the Accelerated Fully Rough Turbulent Boundary Layer

1981 ◽  
Vol 103 (1) ◽  
pp. 153-158 ◽  
Author(s):  
H. W. Coleman ◽  
R. J. Moffat ◽  
W. M. Kays
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Flux ◽  
Turbulent Boundary Layer ◽  
Prandtl Number ◽  
Pressure Gradient ◽  
Turbulent Heat Flux ◽  
Test Surface ◽  
Turbulent Heat ◽  
Turbulent Prandtl Number

Heat transfer behavior of a fully rough turbulent boundary layer subjected to favorable pressure gradients was investigated experimentally using a porous test surface composed of densely packed spheres of uniform size. Stanton numbers and profiles of mean temperature, turbulent Prandtl number, and turbulent heat flux are reported. Three equilibrium acceleration cases (one with blowing) and one non-equilibrium acceleration case were studied. For each acceleration case of this study, Stanton number increased over zero pressure gradient values at the same position or enthalpy thickness. Turbulent Prandtl number was found to be approximately constant at 0.7–0.8 across the layer, and profiles of the non-dimensional turbulent heat flux showed close agreement with those previously reported for both smooth and rough wall zero pressure gradient layers.

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