An Experimental Study of High Rayleigh Number Natural Convection in an Enclosure

1986 ◽  
Author(s):  
Paul W. Giel ◽  
Frank W. Schmidt
Keyword(s):  
Experimental Study ◽  
Natural Convection ◽  
Rayleigh Number

Natural Convection of a Liquid Metal in Vertical Circular Cylinders Heated Locally From the Side

1998 ◽  
Vol 120 (1) ◽  
pp. 108-114 ◽  
Author(s):  
R. Selver ◽  
Y. Kamotani ◽  
S. Ostrach
Keyword(s):  
Experimental Study ◽  
Natural Convection ◽  
Numerical Analysis ◽  
Rayleigh Number ◽  
Thermal Instability ◽  
Experimental Information ◽  
Diameter Ratio ◽  
Circular Cylinders ◽  
Oscillation Frequencies ◽  
Axial Band

An experimental study is made of natural convection in gallium melts enclosed by vertical circular cylinders with localized circumferential heating. Heating is done in an axial band at the mid-height, and both ends of the cylinder are cooled. In the present study, the cylinder aspect (Ar = height/diameter) ratio ranges from 2 to 10, and the Rayleigh number (Ra) ranges from 9.0 × 104 to 3.0 × 107. The Prandtl number is 0.021. Temperature measurements are made at six axial levels around the circumference of the cylinder to study thermal convection in the melt. A numerical analysis is also conducted to supplement the experimental information. When Ra is small, the melt is in steady toroidal motion. Above a certain Ra, the flow becomes nonaxisymmetric as a result of a thermal instability, in the case of Ar larger than 3. With increasing Ra, the motion becomes oscillatory, mainly in the upper half. When Ar is smaller than 3, the toroidal flow becomes nonaxisymmetric and oscillatory at the same time beyond a certain Ra. The conditions for the appearance of oscillations and the oscillation frequencies are investigated in detail.

scholarly journals Experimental Study on Horizontal Cylinders with Triangular Fins under Natural Convection

Energies ◽  
2018 ◽  
Vol 11 (4) ◽  
pp. 836 ◽  
Author(s):  
Gu-Won Lee ◽  
Hyun Kim ◽  
Dong-Kwon Kim
Keyword(s):  
Experimental Study ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Aspect Ratio ◽  
Thermal Resistance ◽  
Thickness Increase ◽  
Nusselt Numbers ◽  
Cooling Devices ◽  
Horizontal Cylinders ◽  
Fin Thickness

In this study, thermal resistances of horizontal cylinders with triangular fins were measured in regard to fin numbers, fins heights, and temperature differences. Thereafter, an empirical correlation was proposed and validated for predicting the Nusselt numbers under the following conditions: Rayleigh number, 200,000–1,000,000; fin aspect ratio, 1.6–5.0; and fin number, 9–72. Finally, with the proposed correlation, the effects of fin numbers, fins heights, and fin thicknesses on the thermal resistances of the horizontal cylinders with triangular fins were investigated. It was shown that the thermal resistance generally increases as the fin number, fin height, and fin thickness increase. It is expected that horizontal cylinders for various cooling devices with triangular fins can be designed based on the findings of the present study.

EXPERIMENTAL STUDY OF NATURAL CONVECTION IN A CAVITY: PRECISE VISUALIZATION METHOD OF TEMPERATURE FIELD

2018 ◽  
Author(s):  
Menghua Duan ◽  
Lin Chen ◽  
Yongchang Feng ◽  
Junnosuke Okajima ◽  
Atsuki Komiya
Keyword(s):  
Experimental Study ◽  
Temperature Field ◽  
Natural Convection ◽  
Visualization Method

AN EXPERIMENTAL STUDY OF A MELTING PROBLEM WITH NATURAL CONVECTION

2019 ◽  
Author(s):  
Yin-Chao Yen ◽  
Chi Tien ◽  
Gary Sander
Keyword(s):  
Experimental Study ◽  
Natural Convection
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