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.

On the Simulation of Turbulent Heat Transfer for Low-Pr Fluid Cross-Flow in Tube Banks

2021 ◽  
Author(s):  
Alessandro Tassone ◽  
Jasper Meeusen ◽  
Andrea Serafini ◽  
Gianfranco Caruso
Keyword(s):  
Heat Transfer ◽  
Cross Flow ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Tube Banks

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 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.

scholarly journals Numerical Analysis of Turbulent Heat Transfer in the Case of Minijets Array

Symmetry ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1785
Author(s):  
Sebastian Gurgul ◽  
Tomasz Kura ◽  
Elzbieta Fornalik-Wajs
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Heated Surface ◽  
Cross Flow ◽  
Turbulent Heat Transfer ◽  
Tetragonal Symmetry ◽  
Strength Analysis ◽  
Turbulent Heat ◽  
Phase Array ◽  
Surface Geometry

The presented numerical investigations show an analysis of the turbulent single-phase array of ten minijets impinging a heated surface, which lead to the intensification of heat transfer between the fluid and the surface. Attention was devoted to the comparison between phenomena occurring for the heated flat and concave surface geometry. The selection of the shapes was based on the impinging jets applications. From the numerical point of view, the focus was placed on a comparison of the Reynolds Averaged Navier–Stokes (RANS) turbulence model implementations in ANSYS Fluent software, and their impact on the modeling precision of the thermal and hydrodynamic boundary layers phenomena. The 3D numerical model was based on the continuity, momentum, and energy transport equations, together with three various RANS turbulence models: k-ω SST Kato-Launder, k-ε RNG Kato-Launder, and Intermittency Transition. The water submerged minijets, characterized by three various values of Reynolds number, were considered. Average surface Nusselt number values for all analyzed cases were compared with the experimental correlations and exhibited the same tendency but differed in detail. Numerically obtained average Nusselt number values agreed with the results of two from three correlations in the range of 10–20%. The flat surface was characterized by higher heat transfer than the concave one and an influence of the cross flow, changing the symmetrical distribution of the Nusselt number, was more visible for it. A cross flow impact was found in fuzzy hexagonal or tetragonal symmetry of this distribution. Additionally, the areas of high temperature gradient values were identified in the region of the strongest jets’ interactions, which can be important for mechanical strength analysis.

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