scholarly journals Discussion: “Incipient-boiling Superheats for Sodium in Turbulent Channel Flow: Effect of Rate of Temperature Rise” (Dwyer, O. E., Strickland, G., Kalish, S., Hlavac, P. J., and Schoener, G. A., 1973, ASME J. Heat Transfer, 95, pp. 159–165)

1973 ◽  
Vol 95 (2) ◽  
pp. 165-165
Author(s):  
Hans K. Fauske
Keyword(s):  
Heat Transfer ◽  
Channel Flow ◽  
Temperature Rise ◽  
Turbulent Channel Flow ◽  
Flow Effect

Incipient-boiling Superheats for Sodium in Turbulent Channel Flow: Effect of Rate of Temperature Rise

1973 ◽  
Vol 95 (2) ◽  
pp. 159-165 ◽  
Author(s):  
O. E. Dwyer ◽  
G. Strickland ◽  
S. Kalish ◽  
P. J. Hlavac ◽  
G. A. Schoener
Keyword(s):  
Experimental Study ◽  
Turbulent Flow ◽  
Experimental Method ◽  
Channel Flow ◽  
Temperature Rise ◽  
Turbulent Channel Flow ◽  
Control Temperature ◽  
Flow Effect ◽  
Temperature Ramp ◽  
And Control

Using sodium, an experimental study was carried out to determine the effect of rate of temperature rise on the incipient-boiling superheat for fully developed, forced turbulent flow. Three different methods of achieving boiling inception were used. The magnitude of the incipient-boiling superheat was found to be quite reproducible and independent of the experimental method as long as the rate of temperature rise (temperature ramp) was kept constant and kept the same. Moreover, the value of the superheat was found to have a strong dependency on the temperature ramp—the greater the ramp, the larger the superheat. The failure to carefully measure and control temperature ramp is apparently one reason why incipient-boiling-superheat data generally show so much scatter, and those from different laboratories so much disagreement.

Heat transfer enhancement of turbulent channel flow using tandem self-oscillating inverted flags

2018 ◽  
Vol 30 (7) ◽  
pp. 075108 ◽  
Author(s):  
Yujia Chen ◽  
Yuelong Yu ◽  
Wenwu Zhou ◽  
Di Peng ◽  
Yingzheng Liu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Channel Flow ◽  
Turbulent Channel Flow ◽  
Transfer Enhancement

Relationship between the heat transfer law and the scalar dissipation function in a turbulent channel flow

2017 ◽  
Vol 830 ◽  
pp. 300-325 ◽  
Author(s):  
Hiroyuki Abe ◽  
Robert Anthony Antonia
Keyword(s):  
Heat Transfer ◽  
Prandtl Number ◽  
Channel Flow ◽  
Dissipation Rate ◽  
Turbulent Channel Flow ◽  
Scalar Dissipation ◽  
Scalar Dissipation Rate ◽  
Mean Velocity ◽  
The Mean ◽  
Logarithmic Dependence

Integration across a fully developed turbulent channel flow of the transport equations for the mean and turbulent parts of the scalar dissipation rate yields relatively simple relations for the bulk mean scalar and wall heat transfer coefficient. These relations are tested using direct numerical simulation datasets obtained with two isothermal boundary conditions (constant heat flux and constant heating source) and a molecular Prandtl number Pr of 0.71. A logarithmic dependence on the Kármán number $h^{+}$ is established for the integrated mean scalar in the range $h^{+}\geqslant 400$ where the mean part of the total scalar dissipation exhibits near constancy, whilst the integral of the turbulent scalar dissipation rate $\overline{\unicode[STIX]{x1D700}_{\unicode[STIX]{x1D703}}}$ increases logarithmically with $h^{+}$. This logarithmic dependence is similar to that established in a previous paper (Abe & Antonia, J. Fluid Mech., vol. 798, 2016, pp. 140–164) for the bulk mean velocity. However, the slope (2.18) for the integrated mean scalar is smaller than that (2.54) for the bulk mean velocity. The ratio of these two slopes is 0.85, which can be identified with the value of the turbulent Prandtl number in the overlap region. It is shown that the logarithmic $h^{+}$ increase of the integrated mean scalar is intrinsically associated with the overlap region of $\overline{\unicode[STIX]{x1D700}_{\unicode[STIX]{x1D703}}}$, established for $h^{+}$ (${\geqslant}400$). The resulting heat transfer law also holds at a smaller $h^{+}$ (${\geqslant}200$) than that derived by assuming a log law for the mean temperature.

DNS of Heat Transfer Reduction in Viscoelastic Turbulent Channel Flows

2015 ◽  
Author(s):  
Kyoungyoun Kim ◽  
Radhakrishna Sureshkumar
Keyword(s):  
Heat Transfer ◽  
Channel Flow ◽  
Reduction Rate ◽  
Turbulent Channel Flow ◽  
Passive Scalar ◽  
Heat Fluxes ◽  
Turbulent Heat Transfer ◽  
Uniform Heat Flux ◽  
Turbulent Heat ◽  
Turbulent Heat Fluxes

A direct numerical simulation (DNS) of viscoelastic turbulent channel flow with the FENE-P model was carried out to investigate turbulent heat transfer mechanism of polymer drag-reduced flows. The configuration was a fully-developed turbulent channel flow with uniform heat flux imposed on both walls. The temperature was considered as a passive scalar. The Reynolds number based on the friction velocity (uτ) and channel half height (δ) is 125 and Prandtl number is 5. Consistently with the previous experimental observations, the present DNS results show that the heat-transfer coefficient was reduced at a rate faster than the accompanying drag reduction rate. Statistical quantities such as root-mean-square temperature fluctuations and turbulent heat fluxes were obtained and compared with those of a Newtonian fluid flow. Budget terms of the turbulent heat fluxes were also presented.

1518 Dissimilar heat transfer enhancement using permeable walls in turbulent channel flow

2015 ◽  
Vol 2015 (0) ◽  
pp. _1518-1_-_1518-3_
Author(s):  
Hisaaki HASEGAWA ◽  
Yuuki AOKI ◽  
Kousuke ISHIKAWA ◽  
Genta KAWAHARA ◽  
Markus UHLMANN ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Channel Flow ◽  
Turbulent Channel Flow ◽  
Transfer Enhancement ◽  
Permeable Walls

Heat transfer in a turbulent channel flow with square bars or circular rods on one wall

2015 ◽  
Vol 776 ◽  
pp. 512-530 ◽  
Author(s):  
S. Leonardi ◽  
P. Orlandi ◽  
L. Djenidi ◽  
R. A. Antonia
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Prandtl Number ◽  
Channel Flow ◽  
Turbulent Channel Flow ◽  
Turbulent Heat ◽  
Turbulent Prandtl Number ◽  
Smooth Wall ◽  
Roughness Elements ◽  
Smooth Channel

Direct numerical simulations (DNS) are carried out to study the passive heat transport in a turbulent channel flow with either square bars or circular rods on one wall. Several values of the pitch (${\it\lambda}$) to height ($k$) ratio and two Reynolds numbers are considered. The roughness increases the heat transfer by inducing ejections at the leading edge of the roughness elements. The amounts of heat transfer and mixing depend on the separation between the roughness elements, an increase in heat transfer accompanying an increase in drag. The ratio of non-dimensional heat flux to the non-dimensional wall shear stress is higher for circular rods than square bars irrespectively of the pitch to height ratio. The turbulent heat flux varies within the cavities and is larger near the roughness elements. Both momentum and thermal eddy diffusivities increase relative to the smooth wall. For square cavities (${\it\lambda}/k=2$) the turbulent Prandtl number is smaller than for a smooth channel near the wall. As ${\it\lambda}/k$ increases, the turbulent Prandtl number increases up to a maximum of 2.5 at the crests plane of the square bars (${\it\lambda}/k=7.5$). With increasing distance from the wall, the differences with respect to the smooth wall vanish and at three roughness heights above the crests plane, the turbulent Prandtl number is essentially the same for smooth and rough walls.

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