Radiation heat transfer affects natural convection of air inside an open-ended cavity with a heated horizontal upper plate and an unheated lower parallel plate. Its effect is the heating of the lower plate, which heats the adjacent fluid layer and could determine secondary motions. In this paper, an experimental study is carried out to describe the effect of high value of surface emissivity on air flow in an open-ended cavity. The investigation is performed by means of wall temperature profiles, smoke visualization, and air temperature measurements. Results are obtained for an emissivity of the horizontal plates equal to 0.8, for aspect ratios between 10.0 and 20.0. By means of flow visualization and local air temperature measurements in the cavity as a function of time, remarkable secondary motions in the cavity are observed for the highest considered surface heat flux ($Ra=8.91×103$, $6.45×104$, and $1.92×105$). Measurement of the air temperature in the cavity also shows that radiation causes and damps secondary motions at the same time. Mean air temperature profiles as a function of the vertical coordinate, at different locations along the longitudinal axis, confirm both the main flow path inside the cavity and radiation effect on convective heat transfer. Finally, correlations for average Nusselt numbers and dimensionless maximum wall temperatures, in terms of Rayleigh number and channel aspect ratio, are proposed for natural convection with or without radiative heat transfer contribution for $2.26×103≤Ra≤1.92×105$ and $10≤2L/b≤20$.

1.
Vafai
,
K.
, and
Ettefagh
,
J.
, 1990, “
The Effects of Sharp Corners on Buoyancy-Driven Flows With Particular Emphasis on Outer Boundaries
,”
Int. J. Heat Mass Transfer
0017-9310,
33
, pp.
2311
2328
.
2.
Manca
,
O.
,
Morrone
,
B.
, and
Nardini
,
S.
, 2000, “
Experimental Analysis of Thermal Instability in Natural Convection Between Horizontal Parallel Plates Uniformly Heated
,”
ASME J. Heat Transfer
0022-1481,
122
, pp.
50
57
.
3.
Manca
,
O.
, and
Nardini
,
S.
, 2007, “
Experimental Investigation on Natural Convection in Horizontal Channels With Upper Wall at Uniform Heat Flux
,”
Int. J. Heat Mass Transfer
,
50
, pp.
1075
1086
. 0017-9310
4.
Lage
,
J. L.
,
Lim
,
J. S.
, and
Bejan
,
A.
, 1992, “
Natural Convection With Radiation in Cavity With Open Top End
,”
ASME J. Heat Transfer
0022-1481,
114
, pp.
479
486
.
5.
Bejan
,
A.
, and
Kimura
,
S.
, 1981, “
Penetration of Free Convection Into a Lateral Cavity
,”
J. Fluid Mech.
0022-1120,
103
, pp.
465
478
.
6.
LeQuere
,
O.
,
Humphery
,
J. A. C.
, and
Sherman
,
F. S.
, 1981, “
Numerical Calculation of Thermally Driven Two-Dimensional Unsteady Laminar Flow in Cavities of Rectangular Cross Section
,”
Numer. Heat Transfer
0149-5720,
4
, pp.
249
283
.
7.
Penot
,
F.
, 1982, “
Numerical Calculation of Two-Dimensional Natural Convection in Isothermal Open Cavities
,”
Numer. Heat Transfer
0149-5720,
5
, pp.
421
437
.
8.
Hess
,
C. F.
, and
Henze
,
R. H.
, 1984, “
Experimental Investigation of Natural Convection Losses From Open Cavities
,”
ASME J. Heat Transfer
,
106
, pp.
333
338
. 0022-1481
9.
Chan
,
Y. L.
, and
Tien
,
C. L.
, 1985, “
A Numerical Study of Two-Dimensional Natural Convection in Square Open Cavities
,”
Numer. Heat Transfer
0149-5720,
8
, pp.
65
80
.
10.
Chan
,
Y. L.
, and
Tien
,
C. L.
, 1985, “
A Numerical Study of Two-Dimensional Natural Convection in Shallow Open Cavities
,”
Int. J. Heat Mass Transfer
0017-9310,
28
, pp.
603
612
.
11.
Chan
,
Y. L.
, and
Tien
,
C. L.
, 1986, “
Laminar Natural Convection in Shallow Open Cavities
,”
ASME J. Heat Transfer
,
108
, pp.
305
309
. 0022-1481
12.
Angirasa
,
D.
,
Pourquié
,
M. J.
, and
,
F. T.
, 1992, “
Numerical Study of Transient and Steady Laminar Bouyancy-Driven Flows and Heat Transfer in a Square Open Cavity
,”
Numer. Heat Transfer, Part A
1040-7782,
22
, pp.
223
239
.
13.
Angirasa
,
D.
,
Eggels
,
J. G.
, and
,
F. T.
, 1995, “
Numerical Simulation of Transient Natural Convection from an Isothermal Cavity Open on a Side
,”
Numer. Heat Transfer, Part A
1040-7782,
28
, pp.
755
768
.
14.
Abib
,
A. H.
, and
Jaluria
,
Y.
, 1995, “
Penetrative Convection in a Stably Stratified Enclosure
,”
Int. J. Heat Mass Transfer
,
38
(
13
), pp.
2489
2500
. 0017-9310
15.
Vafai
,
K.
, and
Ettfagh
,
J.
, 1990, “
Thermal and Fluid Flow Instabilities in Buoyancy-Driven Flows in Open-Ended Cavities
,”
Int. J. Heat Mass Transfer
0017-9310,
33
, pp.
2329
2344
.
16.
Manca
,
O.
,
Morrone
,
B.
, and
Nardini
,
S.
, 2000, “
Visualization of Flow Structures in Natural Convection Between Horizontal Uniformly Heated Parallel Plates
,”
J. Flow Visualization Image Process.
1065-3090,
7
, pp.
159
171
.
17.
Khanafer
,
K.
, and
Vafai
,
K.
, 2000, “
Buoyancy-Driven Flows and Heat Transfer in Open-Ended Enclosures: Elimination of the Extended Boundaries
,”
Int. J. Heat Mass Transfer
,
43
, pp.
4087
4100
. 0017-9310
18.
Khanafer
,
K.
, and
Vafai
,
K.
, 2002, “
Effective Boundary Conditions for Buoyancy-Driven Flows and Heat Transfer in Fully Open-Ended Two-Dimensional Enclosure
,”
Int. J. Heat Mass Transfer
,
45
, pp.
2527
2538
. 0017-9310
19.
,
S.
, and
Kauli
,
H.
, 2004, “
Effects of Plate Separation, Plate Length and Temperature Difference on Buoyancy Driven Heat Transfer in Finite Horizontal Parallel Plates
,”
Heat Mass Transfer
0947-7411,
40
, pp.
293
330
.
20.
Icoz
,
T.
, and
Jaluria
,
Y.
, 2005, “
Numerical Simulation of Boundary Conditions and the Onset of Instability in Natural Convection Due to Protruding Thermal Sources in an Open Rectangular Channel
,”
Numer. Heat Transfer
,
48
, pp.
831
847
. 1040-7782
21.
Turgut
,
O.
, and
Onur
,
N.
, 2007, “
An Experimental and Three-Dimensional Numerical Study of Natural Convection Heat Transfer Between Two Horizontal Parallel Plates
,”
Int. Commun. Heat Mass Transfer
0735-1933,
34
, pp.
644
652
.
22.
Andreozzi
,
A.
,
Jaluria
,
Y.
, and
Manca
,
O.
, 2007, “
Numerical Investigation on Transient Natural Convection in a Horizontal Channel Heated From Upper Wall
,”
Numer. Heat Transf.
,
51
, pp.
815
842
. 1040-7782
23.
Hinojosa
,
J. F.
,
Cabanillas
,
R. E.
,
Alvarez
,
G.
, and
,
C. E.
, 2005, “
Nusselt Number for the Natural Convection and Surface Thermal Radiation in a Square Tilted Open Cavity
,”
Int. Commun. Heat Mass Transfer
0735-1933,
32
, pp.
1184
1192
.
24.
Lin
,
C. X.
, and
Ko
,
S. Y.
, 1994, “
Effect of Surface Radiation on Turbulent Free Convection in an Open-Ended Cavity
,”
Int. Commun. Heat Mass Transfer
0735-1933,
21
, pp.
117
129
.
25.
Yu
,
E.
, and
Joshi
,
Y. K.
, 1999, “
Heat Transfer in Discretely Heated Side-Vented Compact Enclosures by Combined Conduction, Natural Convection, and Radiation
,”
ASME J. Heat Transfer
0022-1481,
121
, pp.
1002
1010
.
26.
Hinojosa
,
J. F.
,
,
C. A.
,
Cabanillas
,
R. E.
, and
Alvarez
,
G.
, 2005, “
Numerical Study of Transient and Steady-State Natural Convection and Surface Thermal Radiation in a Horizontal Square Open Cavity
,”
Numer. Heat Transfer
,
48
, pp.
179
196
. 1040-7782
27.
Chiu
,
W. K. S.
,
Richards
,
C. J.
, and
Jaluria
,
Y.
, 2000, “
Flow Structure and Heat Transfer in a Horizontal Channel Heated From Below
,”
Phys. Fluids
1070-6631,
12
(
8
), pp.
2128
2136
.
28.
Chyu
,
M. C.
, 1987, “
On the Boundary Condition and Data Reduction of Heat Transfer Experiment
,”
Int. Commun. Heat Mass Transfer
0735-1933,
14
, pp.
543
550
.
29.
2005, LABVIEW, Reference Manual, National Instruments, Austin, TX.
30.
Dantec
, 1996, “
Probes for Hot-Wire Anemometry
,” Dantec Measurement Technology Publication No. 196-105-01.
31.
Bruun
,
H. H.
, 1995,
Hot-Wire Anemometry: Principles and Signal Analysis
,
Oxford University Press
,
New York
.
32.
Kline
,
S. J.
, and
McClintock
,
F. A.
, 1953, “
Describing Uncertainty in Single Sample Experiments
,”
Mech. Eng. (Am. Soc. Mech. Eng.)
,
75
, pp.
3
12
. 0025-6501
33.
Moffat
,
R. J.
, 1988, “
Describing the Uncertainties in Experimental Results
,”
Exp. Therm. Fluid Sci.
0894-1777,
1
, pp.
3
17
.