Experimental Investigation of Natural Convection Losses From Open Cavities

Abstract

Experimental results for natural convection in a cavity are reported. Both constrained and unconstrained cavity geometries were studied. Detailed velocity profiles were obtained using Laser doppler velocimetry for Rayleigh numbers between 3 × 1010 and 2 × 1011, corresponding to a constant elevated wall temperature boundary condition. Characteristics of two-dimensional and three-dimensional flows obtained with dye flow visualization are discussed, including boundary layer transition to turbulence, flow patterns in the cavity, and flow outside of the cavity. Local Nusselt number is correlated with local Rayleigh number for constrained and unconstrained cavities.

Experimental and numerical study of turbulent natural convection in an open cubic cavity

“…In literature are reported several studies of heat transfer in open cavities, which can be classified as: (a) numerical , (b) experimental [38][39][40][41] and (c) numerical-experimental [42][43][44]. Most of numerical studies has been conducted with a two-dimensional approach, however the three dimensional description of the phenomena is more realistic.…”

Numerical Studies on Natural Convection Heat Losses from Open Cubical Cavities

“…It is observed from the literature that experimental and numerical studies on natural convection in open cavities have been performed for different cavity shapes, namely, cubical [1][2][3][4][5][6], rectangular [7][8][9][10][11][12][13][14][15][16][17], and square [18][19][20][21][22][23][24]. Studies have also been reported on other cavity shapes used for specific applications like solar thermal receivers [25][26][27][28][29][30][31].…”

“…It was also observed that most of the studies from cubical and rectangular open cavities with a constant temperature back wall boundary condition are limited to Rayleigh numbers of about 10 7 except for studies such as Hess and Henze [3] and Chan and Tien [10], where Rayleigh numbers of about 5 -1.5 × 10 9 are studied. Nusselt number correlations that involve Rayleigh numbers and the inclination effects are proposed.…”

“…Opening ratios of 1 [1-3, 5, 6, 9-13, 16-23, 25, 26], 0.5 [3,8,22,30], 0.6 and 0.4 [7], and 0.25 [30] have been studied. Clausing et al [4], Chakroun et al [14], Elsayed and Chakroun [15], Bilgen and Oztop [24], Stine and McDonald [28], McDonald [29], and Sendhil Kumar and Reddy [31] have analysed different opening ratios ranging from 1 to about 0.1.…”

“…In the studies involving open cavity natural convection, two basic boundary wall conditions are observed: (a) all the walls of the open cavity were heat transfer surfaces at constant temperature [1,2,4,6,8,9,12,18,19,21,22,25,26,[30][31][32], henceforth referred to as isothermal wall boundary condition and (b) only one wall (wall opposite to the aperture) was at constant temperature and the remaining walls were kept adiabatic, henceforth referred to as constant temperature back wall boundary condition [3,5,10,11,13,20,23,24,33]. Other wall boundary conditions such as one wall having constant heat flux and other walls being adiabatic [14][15][16] and nonisothermal wall temperatures [7,[27][28][29] were also studied.…”