Appeal No. 2004-0323 Page 15
Application No. 09/716,045
Larsen's invention relates to an apparatus for redirecting air flow, and more
particularly, to an apparatus for efficiently redirecting a horizontal, planar, radially
inward directed air flow ninety degrees to a vertically directed air flow having a generally
uniform velocity profile. Additionally, Larsen's invention provides an apparatus for
directing a three-dimensional inward directed air flow to a planar radially inward directed
flow as well as an apparatus for directing an air flow having a generally uniform velocity
profile to the inlet of a ducted fan. In the BACKGROUND OF THE INVENTION section
of the patent (column 1, line 16, to column 2, line 27) Larsen teaches that:
Wind tunnels can generally be open circuit designs, wherein the air is
drawn from and discharged to the ambient atmosphere, or closed circuit designs,
wherein the air is recycled. In the case of an open circuit design, in order to
create a vertically discharged air stream, prior art wind tunnels have used a
vertically oriented fan to directly accelerate air which is exhausted to an upper
exit section. Wind tunnels such as these have been used for recreation, such as
re-creating a free-fall environment for training sky divers, or for scientific and
research purposes. When such a tunnel is used for recreational or training
purposes, a user is placed directly into the accelerated air flow, which acts upon
the user's body with sufficient force so as to suspend the user's body at a certain
elevation. The user is thus maintained in the elevated position until the user is
removed from the flow of air, or the air flow is reduced or terminated. When used
for research purposes, an object to be studied is placed in the air stream so that
measurements can be taken. Commonly, smoke tracers are also used so that
the air flow around the object can be observed. In either usage, a relatively
uniform velocity profile is highly desirable.
However, existing vertical wind tunnels as described above have several
drawbacks for these usages. For example, in recreational circumstances, the
user is either elevated directly over or directly beneath the fan or blower motor
and is therefore subjected to noise levels loud enough that ear plugs may be
required to reduce the sound to a tolerable level. Furthermore, the air flow
emanating from the fan is generally quite turbulent and has an uneven velocity
profile, which leads to rough conditions for the user and unpredictable variables
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