Nu-Ra correlations for natural convection at high Ra numbers in air-filled tilted hemispherical cavities with dome oriented upwards. Disk submitted to constant heat flux

Abstract

Purpose

The purpose of this paper is to propose correlations between Nusselt and Rayleigh numbers for the case of inclined and closed air-filled hemispherical cavities. The disk of such cavities is subjected to a constant heat flux. The study covers a wide range of Rayleigh numbers from 5×107 to 2.55×1012.

Design/methodology/approach

Correlations are obtained from numerical approach validated by experimental measurements on some configurations, valid for several angles of inclination of the cavity between 0° (horizontal disk) and 90° (vertical disk) in steps of 15°.

Findings

The statistical analysis of a large number of calculations leads to reliable results covering laminar, transitional and turbulent natural convection heat transfer zones.

Practical implications

The proposed correlations provide solutions for applications in several fields of engineering such as solar energy, aerospace, building, safety and security.

Originality/value

The new relations proposed are the first published for high Rayleigh numbers for this type of geometry. They supplement the knowledge of natural convection in hemispherical inclined cavities and constitute a useful tool for application in various engineering areas as solar energy (thermal collector, still, pyranometer, albedometer, pyrgeometer), aerospace (embarked electronics), building, safety and security (controlling and recording sensors).

Citation

Baïri, A., García de María, J.M., Alilat, N., Laraqi, N. and Bauzin, J.-G. (2015), "Nu-Ra correlations for natural convection at high Ra numbers in air-filled tilted hemispherical cavities with dome oriented upwards. Disk submitted to constant heat flux", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 25 No. 3, pp. 504-512. https://doi.org/10.1108/HFF-12-2013-0335