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The Yoyogi National Stadium was constructed in Tokyo for the Olympic
Games of 1964. Since the Olympics, the stadium has continued to be used
for swimming competitions, but has also been used as a concert hall. A
CFD evaluation of the stadium interior was recently performed by the Shimizu
Corporation to better understand the quality of the air-conditioning system
for both modes of stadium operation.
The Yoyogi stadium is shown with its double-crescent
roof design
The stadium consists of a large open space covered by a hanging-construction
roof with a double-crescent design. The roof is 126 m in length and 120
m wide. Under the roof, numerous nozzles and intakes are located for the
purpose of circulating the air. The stadium also contains stairs and seats,
and as many of these details as possible were included in the 600,000-cell
mesh. FLUENT was used for the turbulent simulations. In an effort to assess
the cooling system on a hot summer day, the roof temperature was set to
30° Celsius.
A 600,000-cell mesh was used for the simulations
When the stadium is used for swimming, the air nozzles and intakes, located
on opposite sides of the building, are operated in an asymmetric pattern
relative to the centerline. The flow-field produced by the nozzles is
counterclockwise above the first f loor seats and clockwise over the second
floor seats. Excellent heat transfer occurs between these counter-rotating
streams, resulting in a uniform temperature distribution in the stadium
with a variation less than 1° C. When compared against test measurements,
the CFD results were found to be in excellent agreement, thereby validating
the model.
For the stadium to be used as a concert hall, it was decided that four
additional nozzles should be activated on one side of the stadium and
deactivated on the other. The resulting flow-field was considerably different
from that in the earlier case, with side-to-side rather than circulating
flow patterns on the different levels. Nevertheless, the temperature distribution
was found to be very uniform for this design as well, in support of the
proposed modifications. As a result of the CFD calculations, the modifications
could be assessed prior to construction, ensuring that the proposed changes
would result in a comfortable environment for the audience members.
The velocity field in stadium mode above the first floor
shows a circulating airflow pattern, with a resultant temperature variation
not more than 1° C
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