THE MOMENTUM AND VORTICITY TRANSFER THEORIES OF TURBULENT HEAT TRANSFER

1954 ◽  
Vol 32 (6) ◽  
pp. 419-429 ◽  
Author(s):  
A. W. Marris
Keyword(s):  
Heat Transfer ◽  
Outer Boundary ◽  
Eddy Diffusivity ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Distribution Law ◽  
Radial Temperature ◽  
Turbulent Region ◽  
Eddy Diffusivities ◽  
Developed Turbulence

The case of heat transfer by a cylindrical turbulent region is examined further theoretically from the standpoint of the vorticity transfer analogy. The radial distribution of the eddy diffusivity for vorticity is considered and, on the logarithmic velocity distribution law for fully developed turbulence, this quantity is found to be negative throughout an interval at the outer boundary of the turbulent region. When this region is excluded from the relevant integrals, results are obtained for the Nusselt modulus and radial temperature distribution for the particular case of Prandtl number equal to the ratio of the eddy diffusivities for vorticity and heat, and are compared with the corresponding results on the momentum transfer analogy theory.

Turbulent Heat Transfer at Low Reynolds Numbers

1969 ◽  
Vol 91 (4) ◽  
pp. 532-536 ◽  
Author(s):  
C. J. Lawn
Keyword(s):  
Heat Transfer ◽  
Gas Flow ◽  
Eddy Diffusivity ◽  
Reynolds Numbers ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Low Reynolds Numbers ◽  
Eddy Diffusivities ◽  
Uniform Wall ◽  
Uniform Wall Heat Flux

A realistic velocity profile and semiempirical values for the ratio of the eddy diffusivities of momentum and heat are used to solve the heat-balance equation for the situation of fully developed gas flow in a pipe with uniform wall heat flux. The predicted heat transfer is higher than the experimental at Reynolds numbers below 104 and this is shown to be due to the inadequacy of the simple eddy-diffusivity hypothesis.

Heat Transfer in Thermal Barrier Coated Rods With Circumferential and Radial Temperature Gradients

1985 ◽  
Vol 107 (1) ◽  
pp. 135-141 ◽  
Author(s):  
B. T. F. Chung ◽  
M. M. Kermani ◽  
M. J. Braun ◽  
J. Padovan ◽  
R. C. Hendricks
Keyword(s):  
Heat Transfer ◽  
Angular Position ◽  
Cross Flow ◽  
Thermal Response ◽  
Axial Direction ◽  
Ambient Air ◽  
Ceramic Coatings ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Radial Temperature

To study the heat transfer in ceramic coatings applied to the heated side of internally cooled hot section components of the gas turbine engine, a mathematical model is developed for the thermal response of plasma-sprayed ZrO2-Y2 O3 ceramic materials with a Ni-Cr-AL-Y bond coat on a Rene 41 rod substrate subject to thermal cycling. This multilayered cylinder with temperature dependent thermal properties is heated in a cross-flow by a high veloctiy flame and then cooled by ambient air. Due to high temperature and high velocity of the flame, both gas radiation and forced convection are taken into consideration. Furthermore, the local turbulent heat transfer coefficient is employed which varies with angular position as well as the surface temperature. The transient two-dimensional (heat transfer along axial direction is neglected) temperature distribution of the composite cylinder is determined numerically.

A Surface Rejuvenation Model for Turbulent Heat Transfer in Annular Flow With High Prandtl Numbers

1978 ◽  
Vol 100 (1) ◽  
pp. 92-97 ◽  
Author(s):  
B. T. F. Chung ◽  
L. C. Thomas ◽  
Y. Pang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Annular Flow ◽  
Circular Tube ◽  
Eddy Diffusivity ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Fully Developed Flow ◽  
High Prandtl Number ◽  
Prandtl Numbers

Heat transfer for high Prandtl number fluids flowing turbulently in a concentric circular tube annulus with prescribed wall heat flux is investigated analytically. This surface rejuvenation based analysis is restricted to thermally and hydrodynamically fully developed flow with constant properties and negligible viscous dissipation. This formulation leads to predictions for the Nusselt Number that are in basic agreement with predictions obtained on the basis of earlier eddy diffusivity models for 30 ≤ Pr ≤ 1000 and 104 ≤ Re ≤ 106.

Turbulent Heat Transfer Studies in Annulus With Inner Cylinder Rotation

1977 ◽  
Vol 99 (1) ◽  
pp. 12-19 ◽  
Author(s):  
T. M. Kuzay ◽  
C. J. Scott
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Annular Channel ◽  
Outer Wall ◽  
Temperature Fields ◽  
Turbulent Heat Transfer ◽  
Experimental Investigations ◽  
Turbulent Heat ◽  
Radial Temperature ◽  
Axial Temperature

Experimental investigations of turbulent heat transfer are made in a large-gap annulus with both rotating and nonrotating inner cylinder. The vertical annular channel has an electrically heated outer wall; the inner wall is thermally and electrically insulated. The axial air flow is allowed to develop before rotation and heating are imparted. The resulting temperature fields are investigated using thermocouple probes located near the channel exit. The wall heat flux, wall axial temperature development, and radial temperature profiles are measured. For each axial Reynolds number, three heat flux rates are used. Excellent correlation is established between rotational and nonrotational Nusselt number. The proper correlation parameter is a physical quantity characterizing the flow helix. This parameter is the inverse, of the ratio of axial travel of the flow helix in terms of hydraulic diameter, per half revolution of the spinning wall.

Investigation of Turbulent Prt Model and the Segmentation Rule for LBE Turbulent Heat Transfer

2020 ◽  
Author(s):  
Li Peiying ◽  
Deng Jian ◽  
Zhong Lei ◽  
Qian Libo ◽  
Cai Rong ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Theoretical Model ◽  
Liquid Metal ◽  
Group Analysis ◽  
Heat Transfer Process ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Radial Temperature ◽  
Renormalization Group Analysis ◽  
Bismuth Alloy

Abstract With liquid metal like lead-bismuth alloy (LBE) acting as a coolant for nuclear reactors, it is necessary to use a more accurate heat transfer relationship and a more reliable Prt model for the low Pr fluid. Because of the low Pr of liquid metal, the thermal conductivity is more dominant than the momentum transfer, which is quite different from ordinary fluids. In this case, the turbulent Prt can better reflect the heat transfer process. In this study, the Prt = A1+A2/Pr form is selected, and the corresponding coefficients are obtained by the renormalization group analysis method, then corrected by Pr. Furthermore, the applicable range and segmentation rule of the turbulent Prt model are discussed, and the obtained Prt segmentation theoretical model is written into CFD. The result shows that, compared with the previously unmodified model, the radial temperature distribution and Nusselt number (Nu) of the annular and bundle channel obtained by RANS method with the improved Prt model is in good agreement with experimental results, and the deviations are within 5%. It is proved that the turbulent Prt segmentation theoretical model proposed in this study is effective and can represent the heat transfer characteristics of liquid metal from the mechanism.

Investigation of a Two-Equation Turbulent Heat Transfer Model Applied to Ducts

2003 ◽  
Vol 125 (1) ◽  
pp. 194-200 ◽  
Author(s):  
Masoud Rokni and ◽  
Bengt Sunde´n
Keyword(s):  
Heat Transfer ◽  
Eddy Diffusivity ◽  
Turbulent Heat Transfer ◽  
Transfer Model ◽  
Turbulent Heat ◽  
Scalar Flux ◽  
Eddy Viscosity Model ◽  
Wide Range ◽  
Flux Model ◽  
Prandtl Numbers

This investigation concerns numerical calculation of fully developed turbulent forced convective heat transfer and fluid flow in ducts over a wide range of Reynolds numbers. The low Reynolds number version of a non-linear eddy viscosity model is combined with a two-equation heat flux model with the eddy diffusivity concept. The model can theoretically be used for a range of Prandtl numbers or a range of different fluids. The computed results compare satisfactory with the available experiment. Based on existing DNS data and calculations in this work the ratio between the time-scales (temperature to velocity) is found to be approximately 0.7. In light of this assumption an algebraic scalar flux model with variable diffusivity is presented.

Sign in / Sign up

Export Citation Format

Share Document