An Expression for Internal Flow Heat Transfer for Polynomial Wall Temperature Distributions

1969 ◽  
Vol 91 (1) ◽  
pp. 175-177 ◽  
Author(s):  
J. W. Mitchell
Keyword(s):  
Heat Transfer ◽  
Wall Temperature ◽  
Internal Flow ◽  
Temperature Distributions ◽  
Flow Heat

Uneven Wall Temperature Effect on Local Heat Transfer in a Rotating Two-Pass Square Channel With Smooth Walls

1993 ◽  
Vol 115 (4) ◽  
pp. 912-920 ◽  
Author(s):  
J.-C. Han ◽  
Y.-M. Zhang ◽  
Kathrin Kalkuehler
Keyword(s):  
Heat Transfer ◽  
Wall Temperature ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Diameter Ratio ◽  
Transfer Coefficients ◽  
Square Channel ◽  
Heat Transfer Coefficients ◽  
Buoyancy Forces ◽  
Flow Heat

The influence of uneven wall temperature on the local heat transfer coefficient in a rotating, two-pass, square channel with smooth walls is investigated for rotation numbers from 0.0352 to 0.352 by varying Reynolds numbers from 25,000 to 2500. The two-pass square channel, composed of 12 isolated copper sections, has a length-to-hydraulic diameter ratio of 12. The mean rotating radius to the channel hydraulic diameter ratio is kept at a constant value of 30. Three cases of thermal boundary conditions are studied: (A) four walls at the same temperature, (B) four walls at the same heat flux, and (C) trailing wall hotter than leading with side walls unheated and insulated. The results for case A of four walls at the same temperature show that the first channel (radial outward flow) heat transfer coefficients on the leading surface are much lower than that of the trailing surface due to the combined effect of Coriolis and buoyancy forces. The second channel (radial inward flow) heat transfer coefficients on the leading surface are higher than that of the trailing surface. The difference between the heat transfer coefficients for the leading and trailing surface in the second channel is smaller than that in the first channel due to the opposite effect of Coriolis and buoyancy forces in the second channel. However, the heat transfer coefficients on each wall in each channel for cases B and C are higher than case A because of interactions between rotation-induced secondary flows and uneven wall temperatures in cases B and C. The results suggest that the effect of uneven wall temperatures on local heat transfer coefficients in the second channel is greater than that in the first channel.

Literature Review of Single Phase Internal Flow Heat Transfer Correlations in Straight Circular Conduits

2011 ◽  
Author(s):  
Amanie N. Abdelmessih ◽  
Erik C. McGuire
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Internal Flow ◽  
Closed Solution ◽  
The Past ◽  
Wide Range ◽  
Flow Heat ◽  
Heat Transfer Correlations ◽  
Time Required ◽  
Enormous Number

An enormous number of empirical and analytical closed solution, single phase, internal flow heat transfer correlations exist in the open literature. This article is a compilation of single phase internal convective heat transfer correlations in straight, circular conduits. These correlations cover convective internal flow of various Newtonian fluids under a wide range of heating conditions, and orientations for the different flow regimes. In the past some engineers extended the use of some correlations beyond their limits. The purpose of this article is to compile internal flow heat transfer correlations in one source, to alleviate time required by the practicing engineer to research the literature for correlations to meet specific conditions.

Use of the Adiabatic Wall Temperature in Film Cooling to Predict Wall Heat Flux and Temperature

2008 ◽  
Author(s):  
Katharine L. Harrison ◽  
David G. Bogard
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flat Plate ◽  
Gas Turbine ◽  
Turbulence Model ◽  
Wall Temperature ◽  
Adiabatic Wall ◽  
Temperature Distributions ◽  
Adiabatic Effectiveness ◽  
Conjugate Model

The adiabatic wall temperature is generally assumed to be the driving temperature for heat transfer into conducting gas turbine airfoils. This assumption was analyzed through a series of FLUENT simulations using the standard k-ω turbulence model. Adiabatic effectiveness and heat transfer experiments commonly documented in literature were mimicked computationally. The results were then used to predict both the heat flux and temperature distributions on a conducting flat plate wall and the predictions were compared to the heat flux and temperature distributions found through a flat plate conjugate heat transfer simulation. The heat flux analysis was compared to previously published work using the realizable k-ε turbulence model. The same conclusions could be drawn for both turbulence models despite differences in simulated adiabatic effectiveness and heat transfer coefficient distributions. Agreement between heat flux predictions and the heat flux from the conjugate simulations correlated well with how closely the adiabatic wall temperature approximated the over-riding gas driving temperature for heat transfer into the wall. In general, the driving temperature for heat transfer was represented well by the adiabatic wall temperature and the heat flux was well predicted. However, in some locations, the heat flux was over-predicted by up to 300%. Since wall temperature is ultimately the parameter of interest for industrial gas turbine design, the conducting flat plate temperature distribution was also predicted. This was done by using the adiabatic effectiveness and heat transfer coefficients found with the standard k-ω turbulence model as boundary conditions in a three dimensional solid conduction simulation. Then metal temperatures predicted in the solid conduction simulation were compared to those found through conjugate analysis. Despite deviations in predicted heat flux and the conjugate model heat flux of up to 300%, deviations in the predicted and the conjugate model non-dimensional metal temperatures were less than 10%. Thus, use of the adiabatic wall temperature as the driving temperature for heat transfer to predict temperature on the surface of a conducting wall results in relatively small errors.

CFD Analysis Prediction of Heat Transfer Coefficient in Rotating Cavities With Radial Outflow

2006 ◽  
Author(s):  
Charles Wu ◽  
Boris Vaisman ◽  
Kevin McCusker ◽  
Roger Paolillo
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Test Data ◽  
Wall Temperature ◽  
Turbulence Models ◽  
Velocity Profiles ◽  
Transfer Coefficients ◽  
Reynolds Analogy ◽  
Temperature Distributions

This paper documents two related investigations. The first investigation was to benchmark commercial CFD code Fluent in rotating cavities for velocity profiles and beat transfer coefficients. The second investigation was to evaluate the methods of extracting heat transfer coefficients from CFD solution with direct method and Reynolds analogy approach. The rotating cavities examined include rotor-stator, contra-rotating and co-rotating disks. The velocity profiles benchmark was conducted prior to heat transfer coefficient benchmark. Several turbulence models were compared for closed rotating cavity flows. The comparisons between test data and CFD results of tangential and radial velocity profiles showed that the SST k-ω turbulence model performed the best among turbulence models tested. Hence, the SST k-ω model was chosen for heat transfer coefficient benchmarking. The comparisons of heat transfer coefficients between test data and CFD results were presented in the form of local Nusselt number. The thermal wall boundary conditions applied to all the computations were curved-fitted wall temperature distributions from available test data. The wall temperature distributions include approximately constant, positive and negative profiles. It was found that the accurate information of the thermal wall temperature distribution was critical to the benchmark and that only the CFD results with well defined information of wall temperature distributions matched well with test data. The Nusselt number extracted from the CFD solution with the Reynolds analogy approach tends to over predict the heat transfer coefficient on the higher radii and only matched test data at low Reynolds number with positive wall temperature profile. The error increases with higher Reynolds number and decreases with larger flow rate.

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