The numerical investigation of the effect of spanwise pressure gradient on heat transfer and a streamwise vortex embedded in a turbulent boundary layer

2002 ◽  
Author(s):  
InSub Lee ◽  
Hong Sun Ryou ◽  
Hei Cheon Yang ◽  
Sang Kyoo Park
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Gradient ◽  
Numerical Investigation ◽  
Streamwise Vortex

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.

Stability of Concave Boundary Layers: Overview of Stability Mechanism and Recent Findings

2008 ◽  
Author(s):  
Ladan Momayez ◽  
Pascal Dupont ◽  
Guillaume Delacourt ◽  
Hassan Peerhossaini
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Streamwise Vortex ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Streamwise Vortices ◽  
Concave Wall ◽  
Centrifugal Instability ◽  
Concave Boundary

A series of experimental measurements of flow and heat transfer under streamwise Go¨rtler vortices shows conclusively that the local surface heat transfer rates can exceed that of the turbulent boundary layer even in the absence of turbulence. We have observed unexpected behavior of heat transfer in a laminar boundary layer on a concave wall at low nominal velocity, a configuration ignored in the literature. In this situation, precise measurements of the wall heat flux show that the heat transfer enhancement is extremely elevated, above that corresponding to the case of a turbulent boundary layer on a flat plate. The nonlinearly developing steady streamwise vortex (primary instability) heat transfer can already bridge the local laminar to turbulent heat transfer values in the absence of turbulence. The analysis shows that for a range of velocities less than a certain critical velocity, the transitional boundary layer is dominated by centrifugal instability. However, the steady streamwise vortices, like steady Taylor vortices between coaxial rotating cylinders, are susceptible to secondary instabilities of the varicose and sinuous modes. In experiments both modes appear to coexist and cause waviness of the primary streamwise vortices. Other results confirm this discussion based on analysis of the influence of a forcing upstream disturbance.

Sign in / Sign up

Export Citation Format

Share Document