<p>The laminar natural convection in air-filled rectangular cavities with and without a
partition on the wall was experimentally investigated. Temperature measurements
and flow visualizations were performed for cases with heated and cooled vertical
walls (corresponding to global Grashof numbers GrH of approximately 1.4 x 10^8 to
1.8 x 10^8) and non-dimensional top wall temperatures θT of 0.52 (insulated) to 2.3.
In the rectangular cavities without the partition and with aspect ratios of 0.5, 1.0
and 2.0, the heated top wall caused the natural convection boundary layer flow to
separate from either the top wall (for the cases with Or ;S 1.2) or the heated vertical
wall (for the cases with θT >~ 1.2) due to the negative buoyancy force. For the
cases with θT >~ 1.2, there is an anti-clockwise recirculating flow in the upper left
corner region. The extent of the recirculating flow decreased with an increase of the
aspect ratio. The temperature gradient in the core region, dθ∞ /d(y/H), increased
with an increase of θT. For a given aspect ratio, dθ∞/d(y/H) changed more rapidly
with the change in θT for the cases with θT <~ 1.2 compared to the cases with θT >~
1.2. The increase in dθ∞/ d(y/H) was more significant for the smaller aspect ratio
cavity. The temperature profiles predicted from the similarity solutions proposed by
Kulkarni et al. [1] and from the non-similarity model developed by Chen and Eichhorn
[2] for natural convection on an isothermal vertical wall in a stratified environment
were compared to the measurements in the current cases. These models were not able to accurately describe the characteristics of the natural convection flow in the
rectangular cavities.</p> <p>An aluminium partition with non-dimensional heights Hp/H of 0.0625 and 0.125 was attached either to the heated vertical wall or top wall at y/H = 0.65,
0.95 and x/H = 0.1, 0.2, 0.4 and 0.6 to study the effect of the partition on the
laminar natural convection flow in a square cavity. The blockage and thermal effects
of the partition resulted in changes in the temperature and flow fields, but were
mainly limited in the vicinity of the partition. The effect of the partition changed
with the height and location of the partition. When the partition was attached to the
heated top wall, a recirculating flow was formed between the partition and the heated
vertical wall. For a given partition height, the structure of this recirculating flow was
dependent on the partition location and θT. A thermal boundary layer developed
along the rear surface of the partition due to the thermal effect of the partition. The
ambient temperature outside the boundary layer and Nu near the corner region were
affected by the partition height due to the changes in the recirculating flow and the
rear surface of the partition.</p> / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/16814 |
| Date | 12 1900 |
| Creators | Wu, Wenjiang |
| Contributors | Ching, Chan, Mechanical Engineering |
| Source Sets | McMaster University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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