TUBULAR INLINE EXHAUST FAN ASSEMBLY
This is an international patent application filed pursuant to
35 USC §363 claiming priority under 35 USC §120 of/to U.S. Pat.
Appl . Ser. No. 61/379, 832 having a filing date of September 3 , 2010
and entitled TUBULAR INLINE FAN ASSEMBLY/HOUSING WITH HOLLOW VANES , the
disclosure of which is hereby incorporated by reference in its
entirety .
TECHNICAL FIELD
The present invention generally relates to a fan housing
characterized by hollow vanes, more particularly, to an exhaust fan
assembly, such as a direct drive tubular inline exhaust fan
assembly, characterized by such fan housing.
BACKGROUND OF THE INVENTION
The transport of deleterious/potentially deleterious gases
and/or the transport /removal of same from spaces so characterized
is an important, oftentimes critical operation. For example, and
without limitation, the venting of high-temperature, particular
laden, toxic, noxious, corrosive, etc. "gases" or fumes from work
places such as laboratories, industrial or chemical processing
areas or other environments such as tunnels are well known.
Heretofore, and generally, such fumes have been either guided to a
tall exhaust stack whereby they are discharged at a height well
above ground/roof level, or, during the process of evacuating such
fumes, make-up or "fresh" air is introduced so as to mix and
thereby dilute the contaminated air, with a high velocity roof top
discharge of the diluted air commonplace.
In the context of direct drive tubular inline fan
housings/assemblies, traditionally they have been characterized by
a so called "bifurcated" design which is intended to isolate, and
to some degree cool a fan motor from the contaminated air stream,
as well as single-thickness vanes to support the fan motor and
"straighten" the air stream "swirl" downstream of the fan impeller,
see e.g., U.S. Pat. No. 7,320,363 B2 (Seliger et al .), incorporated
herein by reference in its entirety. Moreover, in the context of
induced flow fans characteristic of chemical, industrial,
manufacturing fume exhaust operations, such direct drive tubular
inline fan housings/assemblies are characterized by contraction
nozzles for high-speed discharge, and windbands for dilution of
fume efflux with ambient air, see e.g., Seliger et al .
Further still, in the context of induced flow fan assemblies,
fume exhaust accessories include, and may not be limited to,
multiple nozzles of differing outlet areas to accommodate/acheive
operating points/velocities believed advantageous, an isolation
damper to prevent flow reversal through an idle fan in a parallel
fan configuration of a plenum assembly, a bypass damper to maintain
nozzle outlet velocity by drawing upon additional ambient air when
efflux flow is reduced in a variable exhaust system, and/or a
weather management system to prevent precipitation ingress to the
system, structures thereof and the structure within which the
assembly is deployed.
In as much as apparent improvements have been made with regard
to service/maintenance of components of such systems and marginal
efficiencies with regard to operating efficiencies and sound
attenuation for such systems, it is nonetheless believed that
heretofore known functionality may be achieved with a simplified
structure/assembly, e.g., a fan housing, which circumvents,
eliminates or at least reduces what is believed to be unnecessary
momentum and energy losses attendant to any of the functions of
"swirl" straightening, motor cooling/protection, high-speed upblast
discharge, and/or fume efflux dilution, especially at high airflow
rates, while at least maintaining present industry efficiencies as
to operation and/or sound output. Moreover, in relation to induced
flow fan accessories (i.e., the functional objectives thereof), it
is believed that such function can be retained while nonetheless
eliminating heretofore known structures owing to, among other
things, synergistic effects having origins in Applicant's
simplified structure/assembly.
SUMMARY OF THE INVENTION
An improved exhaust fan housing, and exhaust fan assembly so
characterized, is generally provided. The exhaust fan housing
includes a first cylindrical element, a second cylindrical element
interior of the first cylindrical element, and a plurality of
hollow vanes traversing an annular fluid passage chamber delimited
thereby and uniting the first and second cylindrical elements. A
central drive chamber, delimited by the second cylindrical element,
is in fluid communication with ambient air exterior of the first
cylindrical element via the hollow vanes. Each hollow vane is
characterized by spaced apart wall segments which unitingly
terminate so as to delimit a leading edge for each hollow vane,
each of the spaced apart wall segments having a free end or a
closed end delimiting first and second trailing edges for the
hollow vanes.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts a single direct drive mixed flow induced flow
exhaust assembly;
FIG. 2 depicts the exhaust assembly of FIG. 1 in exploded view
to reveal structural particulars and relationships for and/or
between revealed structures;
FIG. 3 depicts, in elevation, a representative, non-limiting
sound attenuated fan assembly having particular utility in relation
to, for example, a single direct drive mixed flow induced flow
exhaust assembly;
FIG. 3A is a section, about line A-A, of the sound attenuated
fan assembly of FIG. 3 ;
FIG. 3B is an alternate view of the section of FIG. 3A;
FIG. 4 depicts, in elevation, the fan housing of the sound
attenuated fan assembly of FIG. 3 ;
FIG. 4A is a section, about line A-A, of the fan housing of
FIG. 4 ;
FIG. 4B is an alternate view of the section of FIG. 4A;
FIG. 5 depicts, in perspective, a representative, non-limiting
hollow vane of the fan housing of FIG. 4 ;
FIG. 5A is an end view of the vane of FIG. 5 ;
FIG. 5B is side view of the vane of FIG. 5 ;
FIG. 5C depicts a flat pattern plan of the vane of FIG. 5 ;
FIG. 6 depicts, in elevation, a first representative, nonlimiting
fan housing shell;
FIG. 6A depicts a flat pattern plan of the fan housing shell
of FIG. 6 ;
FIG. 7 depicts, in elevation, a further representative, nonlimiting
motor housing shell;
FIG. 7A depicts a flat pattern plan of the motor housing shell
of FIG. 7 ;
FIG. 8 depicts, in elevation, a representative, non-limiting
insulated windband assembly of/for the sound attenuated fan
assembly of FIG. 3 ;
FIG. 8A is a section, about line A-A, of the insulated
windband assembly of FIG. 8 ; and,
FIG. 8B is an alternate view of the section of FIG. 8A.
DETAILED DESCRIPTION OF THE INVENTION
With regard to the instant description, and the referenced
figures, a representative exhaust assembly is generally shown in
FIG. 1 , exploded view FIG. 2 , with select structures, adapted or
otherwise, thereof subsequently depicted. For instance, a
representative, non-limiting sound attenuated fan assembly having
particular utility in relation to, for example, a single direct
drive mixed flow induced flow exhaust assembly is shown in FIG. 3 ;
a fan housing of the sound attenuated fan assembly of FIG. 3 is
shown in FIG. 4 ; a representative, non-limiting hollow vane of the
fan housing of FIG. 4 is shown in FIG. 5 ; representative, nonlimiting
alternate motor housing shell configurations are shown in
FIGS. 6 & 7 ; and, windband/windband assembly particulars are
provided for in FIG. 8 .
In advance of further particulars, several generalities are to
be noted. As is widely known and appreciated, in as much as
ventilation systems are commonly associated with buildings, other
occupied structures such as tunnels and the like are commonly
vented, selectively or otherwise. While the subject description
proceeds in the context of building ventilation, the disclosed
assemblies, subassemblies and/or elements thereof, alone or in
combination with other known or later developed structures are
likewise contemplated for application or adaptation in furtherance
of accomplishing a general functional objective of more efficiently
transporting and/or exhausting deleterious fluids from one or more
generally defined spaces.
With general reference to FIGS. 1 & 2 , exhaust assembly 10 may
be fairly characterized by a fan assembly 12, a plenum or mixing
box 14, and a windband assembly 16. Provisions for multiples of the
depicted exhaust assembly, via common place adaptations, are well
known and widely practiced.
A variety of fluid flow paths associated with the exhaust
assembly of FIG. 1 are generally indicated, more particularly,
vented space effluent flow (Q L), by-pass flow (Q ), fan flow (Q ),
entrained flow (Q E), and total flow (Q ). Notionally, QF is
characterized by suction and pressure flow components, and Q is
fairly characterized by first and second components or
contributions, namely, a first by-pass contribution from the
ambient into a fan housing of the fan assembly, and a second bypass
contribution from the ambient into the windband via an annular
gap delimited by the fan housing and the windband (i.e., the lower
periphery thereof as shown) . In light of the foregoing, and as is
generally understood, several relationships are to be noted,
namely :
Q = QE + Q ; Q = QB + QL ; · · Q = QE + QB + QL
Moreover, both dilution and entrainment ratios, D and De, may be
defined as follows:
D = Q /QL; De = Q /QF
In connection to the elements of the exhaust assembly of FIG.
1 , particulars, at least with regard to the plenum and fan
assembly, are generally depicted in the exhaust assembly view of
FIG. 2 . The plenum 14, disposed at the base of the exhaust assembly
10, generally receives vented space effluent flow (Q L) and mixes it
with fresh/ambient air, i.e., by-pass flow (Q ), as previously
noted. Characteristic of such plenums are the mixing box per se 18,
a by-pass damper 2 0 and related weather hood 22, and an isolation
damper 24. Particulars of such plenum or mixers are widely known,
with details provided by, among others, Seliger et al . 636, see
e.g., FIGS. 3A-4, and the associated written description related
thereto .
A fan assembly 12 is in fluid communication with the plenum 14
and may be fairly characterized by first 30 and second 40 fan
assembly portions which are in axial alignment in relation to an
axial centerline of the exhaust assembly 10 as depicted. The first
fan assembly portion 30 generally includes a fan inlet cone 32 in
combination with an inlet cone housing 34. The second fan assembly
portion 40 generally includes a fan housing 42 characterized by
spaced apart inner 44 and outer 4 6 walls, which alone or in
combination delimit: i ) an annular fluid passage chamber 48 between
the inner wall 44 and the outer 4 6 wall; ii) a central drive
chamber 50 circumf erent ially bounded by the inner wall 44 and
adapted to retain a motor for an exhaust fan; and, iii) an exhaust
fan chamber 52 within the outer wall 4 6 and below the inner wall
44. The second fan assembly portion 40 further includes a plurality
of hollow vanes, e.g., airfoil-shaped hollow vanes 80 as depicted,
extending between the inner wall 44 and the outer 46 wall of the
fan housing 42 of the second fan assembly portion 40 so as to
reside within the annular fluid passage chamber 48 thereof.
As will be subsequently and further detailed, the fan housing
42 advantageously includes cylindrical or conical, concentric inner
44 and outer 4 6 walls, cylindrical as depicted, each characterized
by apertures or through holes 54 which are in paired
alignment /registration to delimit passageways, a motor 5 6 within
cylindrical or conical inner wall 44 (i.e., within central drive
chamber 50), a fan wheel 58 within the cylindrical outer wall 4 6
and beneath or below the inner wall 44 (i.e., within the exhaust
fan chamber 52), and a plurality of hollow vanes 80 which reside
within annular fluid passage chamber 48 and delimit partial
passageway walls for each of the aligned or registered aperture
pairs of the inner 44 and outer 4 6 walls. Each of the hollow vanes
80 are characterized by a leading edge 82 at least one trailing
edge 84, e.g., two trailing edges 84 as shown and each delimiting
a partially walled passageway 86 for radial fluid flow from
exterior of the outer wall 44 to and through the inner wall 4 6 of
the fan housing 42 and into the central drive chamber 50.
Advantageously, but not necessarily, the contemplated hollow vanes
are adapted so as to facilitate integration to/with the windband in
furtherance of the support of same via the fan assembly, more
particularly, the fan housing.
With general reference now to the assemblies or subassemblies
of either of FIGS. 3 or 4 , there is shown select subassemblies or
structures of an exhaust assembly. As a preliminary matter, it is
to be noted that improved acoustic performance for the contemplated
exhaust assembly, owing to selective insulation of subassemblies
and/or structures thereof, utilizing a closed cell insulation as
opposed to fiberglass, perf plate, baffles, etc., is generally
realized. More particularly, windband 100 of windband assembly 16
(i.e., its air discharge, e.g., Q , contacting face or surface,
FIG. 3A) , and/or the outer wall 4 6 of the fan housing 42 (i.e., its
air discharge, e.g., QF, contacting face or surface, FIGS. 3A or
4A) are equipped with closed cell insulation 17, e.g., 2 " thick
closed cell foam.
As previously noted, the fan assembly 12 is generally
characterized by fan housing 42, and fan inlet cone housing or fan
housing transition 34 mechanically united thereto, as by bolting
about a flanged interface for the structures as depicted in either
of FIGS. 3B or 4B. The "fan" or impeller of the fan assembly
generally comprises a fan wheel 58 having a wheel back 60 opposite
a rim 62, and a plurality of spaced apart fan blades 64 uniting the
wheel back 60 and the rim 62, and an inlet cone 32 depending from
or adjacent the rim 62 of the fan wheel 58. As a direct drive fan
is contemplated, fan motor 5 6 is operatively linked, via a shaft or
other such coupling means, to fan wheel 58 in furtherance of
imparting motion, i.e., rotation to the fan wheel.
The fan housing 42 of the fan assembly 12 is generally
characterized by, among other features, cylindrical spaced apart
first (e.g., outer 46) and second (e.g., inner 44) concentric
walls, and annular space 48 delimited thereby. In as much as the
outer wall may be fairly characterized as a cylinder having "open"
opposed or opposing ends, i.e., a sleeve or sleeve like structure,
the interior wall may be fairly characterized as cylinder have one
"open" end opposite a "closed" end, namely, and as depicted, an
open "top" and a closed "bottom." Passing initial reference is
likewise made to FIGS. 6A & 7A which, while depicting advantageous,
non-limiting flat pattern plans of/for the interior wall or motor
housing shell, nonetheless notionally represent corresponding flat
pattern plans of/for the outer wall.
In connection to the cylindrical inner wall 44, it generally
defines central drive chamber 50 within which fan motor 5 6 resides.
As indicated, the cylindrical or conical inner wall 44 includes a
base 45 so as to thereby delimit a motor shell for support of the
fan motor, which is adapted in furtherance of operative union of
the fan motor to the fan wheel. Moreover, and as is best
appreciated with reference to either of FIGS. 6/6A or 7/7A, inner
wall 44 (e.g., FIG. 6 or 7 ) includes spaced apart apertures 54,
advantageously, but not exclusively, as laid out and configured as
per FIGS. 6A & 7A. Via the contemplated arrangement /configuration
of the inner wall or motor housing shell, the motor/central drive
chamber is thereby isolated from vented space exhaust, more
particularly, in the previously established vernacular, while
entrained flow QE passes into the motor housing shell, vented space
exhaust QL, by-pass flow Q and fan flow Q do not pass into or
through the motor housing shell.
In connection to the cylindrical outer wall 46, it, in
combination with or in relation to the cylindrical or conical inner
wall 44, delimits annular space 48 into and through which several
flows are associated, as well as a volume, i.e., chamber 52, within
which the fan wheel resides. As previously indicated, cylindrical
outer wall 46, as cylindrical inner wall 44, includes spaced apart
apertures 54 advantageously laid out and configured to mimic those
of the inner wall 44 of the central drive chamber 50, and to be in
opposition (i.e., registered or registering paired opposition) with
regard to same so as to delimit passageways, i.e., entrained flow
QE component (see e.g., FIG. 1 ) passageways 86.
As is notionally depicted (see e.g., FIG. 4B) , annular space
or chamber 48 of fan housing 42 is advantageously and fairly
characterized as "ring" of constant "width" throughout its
"height." More particularly, and with reference to FIG. 4A,
dimension "d" between the cylindrical inner and outer walls is
preferably, but not necessarily, substantially constant.
Traversing the annular space of the fan housing are passageway
walls which unite the cylindrical inner and outer walls, more
particularly, which link paired spaced apart apertures or through
holes of the inner and outer walls of the fan housing.
Advantageously, but not necessarily, the passageway walls are
partial walls, i.e., not continuous, and more particularly, the
passageway walls are configured as airfoil-shaped hollow vanes, see
e.g., FIG. 5 or 5A. Via the subject relation for, between and among
the cylindrical or conical inner wall, cylindrical outer wall, and
the passageway walls therebetween, each of the vented space flow
QL, by-pass flow Q , and fan flow Q pass through the annular space
of the fan housing, with, as previously noted, an entrained flow QE
component passing through the passageways of the fan housing.
With general reference now to the structure of FIG. 5 and
associated views thereof in FIGS. 5A-5C, an advantageous, nonlimiting
passageway wall, e.g., hollow vane 80, is depicted. As
preliminary matter, the structure of FIG. 5 is part and parcel of
the fan housing of, for example. FIG. 3 , and, not inconsistent with
the passageways of FIG. 6 . Moreover, a further, alternate, nonlimiting
passageway wall is noted in connection to the fan housing
of, for example, FIG. 2 , and not inconsistent with the passageways
of FIG. 7 .
Hollow vane 80 is generally characterized by leading edge 82,
i.e., a "front," "lower" (as depicted) or down-stream structure,
from which extends first and second spaced apart passageway wall
segments 88 (see e.g., FIG. 5A) . Each of the first and second
spaced apart passageway wall segments 88 have free end portions
which delimit trailing edges 84, i.e., "back," "upper" (as
depicted) or up-stream structures, for hollow vane 80 which delimit
partial walled passageway 86 (see e.g., FIG. 5 ) .
In connection to the passageway wall structures, and as
previously noted, each may be fairly characterized as an airfoilshaped
hollow vane. Attendant to such structures are generally
known properties and relationships, see e.g., "Wing Geometry
Definitions, " NASA, Glenn Research Center,
11 :// i t .na sa . ov/a 1ane./ eor .htrn 1 incorporated herein, in
its entirety, by reference.
With regard to each of the passageway walls or wall
structures, leading edge 82 thereof generally delimits pressure (P)
and suction (S) "sides" or surfaces of/for the structure as
indicated, and, as an aid to further discussion, the trailing edge
portions 84 of hollow vanes 80 are indicated as pressure (TE ) and
suction (TE S) trailing edges. As is generally indicated, the
pressure surface of the passageway wall structure is
advantageously, but not necessarily, linear (i.e., the pressure
surface linearly extends from the leading edge) . Moreover, a first
portion or segment 90 of the suction surface proximal to leading
edge 82 generally diverges from the pressure surface, with a second
portion or segment 92 of the suction surface advantageously, but
not necessarily, being in a spaced apart parallel relationship with
the pressure surface of the hollow vane/passageway wall structure.
As previously noted, the passageway wall structure may be
fairly characterized as an airfoil or airfoil-like. In connection
to vane geometry, more particularly, airfoil geometry, several
definitions and structural features/relationship are to be noted,
particulars to follow generalities.
Generally, as is well known (see "Wing Geometry Definitions") ,
the straight line drawn from the leading to trailing edges of the
airfoil is called the chord line. The chord line cuts the airfoil
into an upper surface and a lower surface. A plot of the points
that lie halfway between the upper and lower surfaces yields a
curve called the mean camber line. For a symmetric airfoil, the
upper surface is a reflection of the lower surface and the mean
camber line will overlay the chord line, however, more often than
not, the mean camber line and the chord line are two separate
lines, with the maximum distance between the two lines referred to
as the camber (C) , i.e., a measure of the curvature of the airfoil,
with high camber representing a high curvature. The maximum
distance between the upper and lower surfaces is called the
thickness (TH) .
Particularly, with reference to the contemplated airfoil or
airfoil-like passageway wall structure, the distance from the
leading to trailing edges is called the chord, with chord lengths
generally depicted or referenced, maximum, for each of the pressure
and suction surfaces of/for the passageway walls or wall structures
(FIG. 5A) , i.e., maximum chord lengths "LPS" (pressure) and "LSS"
(suction) . A leading edge radius is generally noted as "RLE," with
leading and trailing edge skew angles (SALE and SA E , respectively) ,
FIG. 5B, being a departure from "horizontal" as measured from a
plane that is normal to the axial direction and/or mean airflow
direction, e.g., SA equals 0 ° for the depicted suction surface
trailing edge of FIG. 5B. Moreover, vane chord (V) and chord ratio
(CR) are generally defined as follows:
L = max (LPS, LSS); CR = min(LPS, LSS)/L
In light of the foregoing, the following parameter ranges are
contemplated, and believed advantageous, though not necessarily
limiting :
CR = 10 to 100%
TH/L = 1 to 50%
C/L = 0 to 25%
RLE/L = 0 to 25%
SALE = -50 to +50°
SA E = -80 to +80°
Moreover, with regard to the number of hollow vanes for a given
application, while there exists a structural tension between the
cylindrical outer and inner walls, i.e., the motor, and thus the
motor shell or inner wall are structurally supported by the outer
wall of the fan housing, it is believed that an advantageous, nonlimiting
relationship exists between the number of hollow vanes and
the nature of the fan wheel/impeller. More particularly, the number
of hollow vanes "n" may be generally correlated to/with the number
of impeller blades "x" via the expression n = x +/- 1 , with n
advantageously thereafter selected so as to be a prime number,
namely, the next highest or lowest prime number "n."
In as much as the hollow vanes may be configured so as to have
an asymmetrical leading edge (i.e., a lack of symmetry about a
leading edge center line, or, in the aforementioned semantic, the
mean camber line does not fall upon the chord line) , the hollow
vanes are likewise contemplated to be configured to have a
symmetrical leading edge (i.e., the mean camber line falls upon the
cord line) . Such straight centerline hollow vane configuration is
believed especially advantageous wherein flow reversibility is a
consideration. For example, and without limitation, emergency
tunnel ventilation utilizes reversible jet fans in furtherance of
handling fire and chemical emergencies in underground tunnels. With
a jet fan housing characterized by hollow vanes having oval or
other symmetric configuration, greater fresh air introduction as an
aid to extended motor operation is believed possible, with improved
thrust realized.
Returning briefly to the representation of the partial
passageway wall of FIG. 5 or 5B, as well as select contextual
representations thereof as will be noted, it is advantageously
contemplated to include/incorporate a flange or tab 94 in
furtherance of supporting a windband 100 or windband assembly 16.
Each of the hollow vanes 80 is generally adapted to include a
flange or tab 94 which outwardly and upwardly extends from a wall
segment of the spaced apart passageway wall segments delimiting the
hollow vane (see, e.g., FIG. 4A) , more particularly, as shown, the
pressure surface of the hollow vane (see e.g., FIG. 4 or FIG. 5B) .
With reference now to FIG. 8 and the sectional views thereof,
a preferred, non-limiting windband assembly 16 is noted. Again, as
was previously noted with regard to the cylindrical outer wall of
the fan housing, an interior surface or face of the windband 100 of
the windband assembly 16 is adapted to include a closed cell foam
insulation 17 in furtherance of improved acoustic performance of
the exhaust fan housing/exhaust fan assembly. Moreover, as
indicated, a windband flange 102 is held interior of a lower
peripheral rim 104 of the windband 100, and spaced apart therefrom,
via radially spaced apart brackets 106. As should be readily
appreciated with reference to, e.g., FIG. 3B, the windband brackets
106 are operatively mated with the flanges or tabs 94 of the wall
segment of the spaced apart passageway wall segments of hollow
vanes 80 (see, e.g., FIG. 4A) .
Thus, in light of the foregoing assemblies, subassemblies, and
structures, heretofore known exhaust fan housing or housing related
elements such as, among other things, single thickness vanes and
contraction nozzles, are eliminated while nonetheless retaining the
functions of those elements. Moreover, via the described and/or
depicted assembly elements, their relationships and
interrelationships, improved pressure versus flow characteristics
are noted with reference to heretofore known exhaust assemblies.
Further still, improved sound attenuation is likewise achieved via
the described and/or depicted assembly elements, their
relationships and interrelationships.
Finally, since the structures of the assemblies/mechanisms
disclosed herein may be embodied in other specific forms without
departing from the spirit or general characteristics thereof, some
of which forms have been indicated, the embodiments described and
depicted herein/with are to be considered in all respects
illustrative and not restrictive. Accordingly, the scope of the one
or more disclosed inventions is/are as defined in the language of
the appended claims, and includes not insubstantial equivalents
thereto.

That which is claimed:
1 . An exhaust fan housing comprising a first cylindrical or conical
element, a second cylindrical element interior of said first
cylindrical or conical element, and a plurality of partial
passageway walls operatively uniting said first cylindrical or
conical element and said second cylindrical element, an interior
space delimited by said second cylindrical element in fluid
communication with ambient air exterior of said first cylindrical
or conical element via partial passageway walls of said plurality
of partial passageway walls, each partial passageway wall of said
plurality of partial passageway walls characterized by spaced apart
passageway wall segments which unitingly terminate so as to delimit
a leading edge for each partial passageway wall of said partial
passageway walls, each of said spaced apart passageway wall
segments having a free end delimiting first and second trailing
edges for each partial passageway wall of said partial passageway
walls .
2 . The exhaust fan housing of claim 1 wherein a first wall
passageway wall segment of said spaced apart passageway wall
segments is characterized by a first chord length, and a second
wall passageway wall segment of said spaced apart passageway wall
segments is characterized by a second chord length, said first
chord length being greater than said second chord length.
3 . The exhaust fan housing of claim 1 wherein a first wall
passageway wall segment of said spaced apart passageway wall
segments is characterized by a first chord length, and a second
wall passageway wall segment of said spaced apart passageway wall
segments is characterized by a second chord length, said first
chord length being substantially equivalent to said second chord
length .
4 . The exhaust fan housing of claim 1 wherein a first wall
passageway wall segment of said spaced apart passageway wall
segments is a pressure surface characterized by a first chord
length, and a second wall passageway wall segment of said spaced
apart passageway wall segments is a suction surface characterized
by a second chord length, said first chord length being greater
than said second chord length.
5 . The exhaust fan housing of claim 1 wherein a first wall
passageway wall segment of said spaced apart passageway wall
segments is a pressure surface characterized by a first chord
length, and a second wall passageway wall segment of said spaced
apart passageway wall segments is a suction surface characterized
by a second chord length, said first chord length being
substantially equivalent to said second chord length.
6 . The exhaust fan housing of claim 1 wherein each trailing edge of
said first and second trailing edges is characterized by a skew
angle of about zero degrees.
7 . The exhaust fan housing of claim 1 wherein each trailing edge of
said first and second trailing edges of each of said spaced apart
passageway wall segments is characterized by a skew angle within a
range of about -80 to +80 degrees.
8 . The exhaust fan housing of claim 1 wherein said leading edge for
each partial passageway wall of said partial passageway walls is
characterized by a skew angle of about zero degrees.
9 . The exhaust fan housing of claim 1 wherein said leading edge for
each partial passageway wall of said partial passageway walls is
characterized by a skew angle within a range of about -50 to +50
degrees .
10. The exhaust fan housing of claim 1 wherein said leading edge
for each partial passageway wall of said partial passageway walls
is characterized by a leading edge radius to maximum chord length
ratio having a value within a range of about 0-0.25.
11. The exhaust fan housing of claim 1 wherein said each partial
passageway wall of said plurality of partial passageway walls is
characterized by a chord ratio having a value within a range of
about 0.1-1.0.
12. The exhaust fan housing of claim 1 wherein said each partial
passageway wall of said plurality of partial passageway walls is
characterized by a thickness to minimum chord ratio having a value
within a range of about 0.01-0.5.
13. The exhaust fan housing of claim 1 wherein said each partial
passageway wall of said plurality of partial passageway walls is
characterized by a camber to minimum chord ratio having a value
within a range of about 0-0.25.
14. The exhaust fan housing of claim 1 wherein one passageway wall
segment of said spaced apart passageway wall segments is adapted to
include a tab for mated union with a portion of a windband assembly
in furtherance of supporting same.
15. The exhaust fan housing of claim 1 wherein one passageway wall
segment of said spaced apart passageway wall segments is adapted to
include an upwardly extending tab for mated union with a portion of
a windband assembly in furtherance of supporting same.
16. The exhaust fan housing of claim 1 further comprising closed
cell insulation, an interior surface of said first cylindrical
element adapted to include said closed cell insulation.
17. The exhaust fan housing of claim 1 wherein a spacing for and
between said first and second cylindrical elements is substantially
constant along a shared axial centerline for each of said first and
second cylindrical elements.
18. The exhaust fan housing of claim 1 further comprising a
directly driven impeller, said impeller housed within said first
cylindrical element and below said second cylindrical element.
19. The exhaust fan housing of claim 18 wherein said impeller is
characterized by "x" number of vanes, a number of partial
passageway walls "n" of said plurality of partial passageway
equating to a prime number satisfying n = x +/- 1 , or a next
higher/lower value of the expression which is a prime number.
20. The exhaust fan housing of claim 1 wherein said leading edge
for said partial passageway wall is symmetrical about a centerline
thereof .
21. The exhaust fan housing of claim 2 0 further comprising closed
cell insulation, an interior surface of said first cylindrical
element adapted to include said closed cell insulation.
22. The exhaust fan housing of claim 1 wherein said leading edge
for said partial passageway wall is asymmetric about a centerline
thereof .
23. The exhaust fan housing of claim 22 further comprising closed
cell insulation, an interior surface of said first cylindrical
element adapted to include said closed cell insulation.
24. An exhaust fan assembly comprising:
a . a plenum for receipt of exhaust and bypass flow;
b . a fan assembly in fluid communication with said plenum and
characterized by first and second fan assembly portions, said
first portion comprising a fan inlet cone in combination with
an inlet cone housing, said second portion comprising a fan
housing characterized by spaced apart inner and outer walls,
which alone or in combination delimit i ) an annular fluid
passage chamber between said inner wall and said outer wall,
ii) a central drive chamber circumf erent ially bounded by said
inner wall and adapted to retain a motor for an exhaust fan,
and iii) an exhaust fan chamber within said outer wall and
below said inner wall, and a plurality of hollow vanes
extending between said inner wall and said outer wall of said
fan housing of said second fan assembly portion so as to
reside within said annular fluid passage chamber thereof, each
hollow vane of said hollow vanes characterized by a leading
edge and two trailing edges, each of said inner and outer
walls adapted such that said each hollow vane delimits a
partially walled passageway for radial fluid flow from
exterior of said outer wall to and through said inner wall and
into said central drive chamber; and,
c . a windband assembly operatively linked to said fan
assembly, said windband assembly characterized by a plurality
of brackets adapted for mated securement to a portion of each
hollow vane of said plurality of hollow vanes in furtherance
of supporting said windband assembly in relation to said fan
housing .
25. An exhaust fan assembly of claim 24 wherein an inner surface of
a windband of said windband assembly is equipped with closed cell
foam in furtherance of sound attenuation.
26. An exhaust fan assembly of claim 24 wherein said annular fluid
passage chamber between said inner wall and said outer wall is
characterized by sound attenuation material.
27. An exhaust fan assembly of claim 24 wherein an inner surface of
said inner wall is equipped with closed cell foam in furtherance of
sound attenuation.
28. An exhaust fan assembly of claim 27 wherein an inner surface of
a windband of said windband assembly is equipped with closed cell
foam in furtherance of sound attenuation.