Appeal No. 2004-0323 Page 16
Application No. 09/716,045
for the researcher. These problems are increased by the fact that most vertical
wind tunnels of this type utilize a standard aircraft propeller to accelerate the air
which further contributes to the heightened noise levels and the uneven velocity
profiles.
Additionally, the positioning of the fan motor in a vertically upright
orientation presents its own set of engineering obstacles. First, in order to create
the desired laminar flow, the length of the entire assembly from the fan drive
motor to the upper exit section can be quite long. Therefore, in order to house
the necessary equipment and place the upper exit section of the wind tunnel at
an easily accessible location, either significant excavation or construction of an
elevation structure must be completed which can greatly increase the expense
and complexity of the wind tunnel construction. Furthermore, additional ductwork
has to be built to provide inlet air for the fan, further adding to construction
expense. Even more significantly, though, is the fact that the vertical orientation
of the fan motor places more stress on the motor bearings than a horizontal
orientation would, thereby increasing maintenance expense and reducing the life
span of the motor.
In order to overcome these problems, wind tunnels have been built to
create vertical air flows using generally horizontally oriented fans. For example,
prior art wind tunnels have been made for creating a vertical air flow using
horizontal fans whereby the horizontal fan accelerates air through a run of
horizontal ductwork after which the air is turned to a vertical direction using a
vertically angled baffle. However, prior art apparatuses using this method have
encountered problems. For instance, the velocity profile of the air flow leaving
the tunnel is not as uniform or consistent as is generally required or desired.
Furthermore, the baffles used for redirecting the flow is very inefficient, resulting
in unacceptable energy losses, and therefore lower than desired air flow
velocities.
Accordingly, there is a need for an apparatus for creating a vertical flow of
air which provides relatively uniform flow velocities, which is relatively quiet in
operation, which is of simple design and construction, and which can be
assembled and maintained at a low cost. Accordingly, there also exists a need
for an apparatus which can efficiently redirect air flow from a generally horizontal
direction to a generally vertical direction. There also exists a need for an
apparatus which can redirect a three-dimensional, inward directed air flow to a
generally planar radially-inward directed flow. Furthermore, there exists a need
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