U.S. patent number 3,585,919 [Application Number 04/820,377] was granted by the patent office on 1971-06-22 for fluid handling system and method.
This patent grant is currently assigned to Aero-Dyne Manufacturing, Inc.. Invention is credited to Clifford Culpepper, Jr..
United States Patent |
3,585,919 |
Culpepper, Jr. |
June 22, 1971 |
FLUID HANDLING SYSTEM AND METHOD
Abstract
A fluid handling method and system in which fluid flow through a
hollow casing is distributed in accordance with a predetermined
profile along an elongate slot in the casing of relatively high
aspect ratio by the provision of internal flow diverting baffle
means interposed between communicating conduit means of relatively
low aspect ratio and the slot and blocking direct fluid flow
therebetween while diverting the flow into a predetermined profile
along the slot.
Inventors: |
Culpepper, Jr.; Clifford
(Charlotte, NC) |
Assignee: |
Aero-Dyne Manufacturing, Inc.
(Charlotte, NC)
|
Family
ID: |
25230606 |
Appl.
No.: |
04/820,377 |
Filed: |
April 30, 1969 |
Current U.S.
Class: |
454/253;
55/DIG.36; 126/299D |
Current CPC
Class: |
F24F
7/08 (20130101); Y10S 55/36 (20130101) |
Current International
Class: |
F24F
7/08 (20060101); F24f 013/00 () |
Field of
Search: |
;98/33,35,62,8,10,115K |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wye; William J.
Claims
I claim:
1. In a fluid distribution system including conduit means for
containing a fluid flow and a hollow manifold casing of
predetermined cross-sectional area interposed between said conduit
means and an enclosure for flow of fluid through said casing
between said conduit means and said enclosure, said casing having a
wall with an elongate slot therein for fluid flow distribution and
said slot having an aspect ratio relatively greater than the aspect
ratio of said conduit means at the location of communication
thereof with said casing, an improvement comprising baffle means
having a cross-sectional area less than that of said casing and
mounted within said casing between said slot and said conduit means
for distributing the volume of fluid flowing through the slot in a
predetermined profile therealong by mechanically blocking fluid
flow through the interior of said casing and diverting the fluid
flow to follow predetermined flow paths longitudinally within said
casing.
2. A fluid distribution system according to claim 1 wherein the
direction of fluid flow is from said conduit means into said casing
and outwardly through said slot.
3. A fluid distribution system according to claim 1 wherein the
direction of fluid flow is inwardly through said slot and through
said casing into said conduit means.
4. A fluid distribution system according to claim 1 wherein said
baffle means defines with said casing a tuned port having an open
area distributed relative to said slot in approximation to a
squared function affecting fluid flow longitudinally within said
casing, said baffle means and said slot cooperating for
distributing the volume of fluid flowing through said slot
uniformly therealong.
5. In an air handling system including conduit means for containing
an air flow and a hollow manifold casing of predetermined
cross-sectional area interposed between said conduit means and an
enclosure for flow of air through said casing between said conduit
means and said enclosure, said casing having a wall with an
elongate slot therein for fluid flow distribution and said slot
having an aspect ratio relatively greater than the aspect ratio of
said conduit means at the location of communication thereof with
said casing, an improvement comprising baffle means having a
cross-sectional area less than that of said casing and mounted
within said casing between said slot and said conduit means for
defining with said casing a tuned port distributed relative to said
slot in a predetermined nonuniform manner approximating a
predetermined mathematical function and for distributing the volume
of air flowing through the slot in a predetermined profile
therealong by mechanically blocking air flow through the interior
of said casing and diverting the air flow to follow predetermined
flow paths longitudinally within said casing while bleeding
portions of the air flow through said tuned port to said slot.
6. An air handling system according to claim 5 wherein said conduit
means includes a plurality of coupling conduits directly connected
to said hollow casing and wherein said baffle means has a
cross-sectional area distributed relative to said slot in
approximation to said mathematical function and further in ratio to
the position of said plurality of coupling conduits to one another
and to said slot.
7. An air handling system according to claim 5 wherein said conduit
means includes a single coupling conduit directly connected to said
hollow casing and wherein said baffle means has a cross-sectional
area so distributed as to define with said casing a pair of
generally triangular open areas diverging one from the other
longitudinally of said slot.
8. In a flowing gas material conveying system including conduit
means for containing a flow of gas and material conveyed by the gas
and a hollow manifold casing of predetermined cross-sectional area
interposed between said conduit means and an enclosure for gas and
material flow through said casing between said conduit means and
said enclosure, said casing having a wall with an elongate slot
therein for flow distribution and said slot having an aspect ratio
relatively greater than the aspect ratio of said conduit means at
the location of communication thereof with said casing, an
improvement comprising baffle means having a cross-sectional area
less than that of said casing and mounted within said casing
between said slot and said conduit means for defining with said
casing a tuned port distributed relative to said slot in a
predetermined nonuniform manner approximating a predetermined
mathematical function and for distributing the volume of flow
through the slot in a predetermined profile therealong by
mechanically blocking flow through the interior of said casing and
diverting the flow to follow predetermined flow paths
longitudinally within said casing while bleeding portions of the
air flow through said tuned port to said slot, the open areas of
said slot and said tuned port cooperating for maintaining the
velocity of gas flow through said conduit means and casing at least
equal to a predetermined velocity for continuing flow of conveyed
material.
Description
The present invention relates to a fluid handling system and method
in which fluid flow is distributed in a predetermined manner along
an elongate slot.
Designers of fluid handling systems, and particularly gas (air)
handling systems, have long recognized that, within the limitations
established by the physical properties of the fluid being handled,
controlled distribution of flow from a region of higher pressure
through an opening to a region of lower pressure is obtained only
by careful establishment of flow conditions relative to that
opening. Elongate slots of high aspect ratio are commonly used to
provide a relatively large flow area which is adapted to be fitted
into conventional construction and, in the specific instance of
flow to be uniformly distributed along elongate, high aspect ratio,
slots or port openings, reliance has heretofore been placed upon
establishing conditions approximating those known as "plenum
conditions." Heretofore, plenum conditions have been obtainable
only by providing large plenum volumes both upstream and downstream
of the slot so that the total pressure of the fluid is given the
opportunity to uniformly distribute itself along the slot on both
the upstream and downstream sides thereof. As herein used, total
pressure includes both static pressure and velocity pressure and is
defined as the total kinetic and potential energy of a unit volume
of the fluid, existing by virtue of the fluid density, velocity,
and degree of compression if applicable.
As has been appreciated by fluid system designers, the attainment
of plenum conditions for an elongate slot presents substantial
difficulty, particularly in connection with gases, in that the
plenum volumes required become excessively large as the length of
the slot becomes greater.
In attempting to apply the methods of conventional design to fluid
handling systems in which fluid flow is to be induced through an
elongate slot, no entirely satisfactory solution has been found
heretofore for reducing the plenum volumes required. Thus,
minimization of the plenum volumes has required acceptance of
variations in flow conditions along an elongate slot, particularly
where the aspect ratios of the elongate slot and a connecting
conduit communicating with a plenum chamber for flow of fluid
relative thereto and through the slot are different.
As herein used, the term "aspect ratio" refers to a number obtained
by dividing the greater dimension of a port or fluid flow opening
by the least dimension thereof. Thus, the aspect ratio of a round
conduit or square conduit is expressed as one, while all other
aspect ratios are expressed as numbers greater than unity. Such
expression implies that the ratio is 1:1, with the first expressed
dimension varying to show the extent to which the greater dimension
exceeds the lesser dimension of a flow opening or port. The
influence of aspect ratio on nonuniform distribution of flow
through an elongate slot results from the vena contracta effect of
flow moving relative to the communicating conduit of lesser aspect
ratio, and thus precluding uniform distribution of flow along the
elongate slot. It is this factor which makes the special case of
uniformly distributed flow more difficult to obtain than other
profiles of flow and has led to study of that special case.
The profiling of fluid flow along an elongate slot resulting from
differences in aspect ratio between the elongate slot and a
communicating conduit and the relative positioning of the conduit
to the elongate slot is highly desirable to obtain a desired
predetermined profile of flow. Where such aspect ratio differences
and positioning are consciously chosen, some degree of controlled
nonuniform distribution of fluid flow along an elongate port is
achievable. However, such techniques still fail to meet the
conditions required in a substantial number of instances.
With the above discussion in mind, it is an object of the present
invention to minimize the space required by a plenum volume in one
flow direction from an elongate slot while providing a fluid
handling system in which the profile of flow along the elongate
slot is controllable in predetermined manner. In realizing this
object of the present invention, the possibility is opened of
economically constructing a fluid handling system heretofore
considered desirable but unobtainable for economical reasons.
Yet another object of the present invention is to obtain a
uniformly distributed volume of fluid flow, particularly air,
through an elongate slot of vary high aspect ratio, in order to
promote more uniform circulation of the air through a selected area
or an enclosed area such as a building. In realizing this object of
the present invention, the volume required in a plenum chamber on
one side of the elongate slot is minimized by the adoption of a
method of operation in which fluid flow is diverted from the
shortest flow path otherwise possible between the elongate slot and
a coupling conduit operatively communicating with the plenum
chamber and is distributed along the slot in a predetermined manner
through the use of a baffle of unique design for given conditions
of aspect ratios, relative positions, desired profile, etc.
Some of the objects and advantages of the invention having been
stated, others will appear as the description proceeds, when taken
in connection with the accompanying drawings, in which:
FIG. 1 is an elevation view, in section, through a building
structure incorporating a fluid handling system in accordance with
the present invention;
FIG. 2 is an enlarged perspective view of portions of the fluid
handling system incorporated in the building structure of FIG.
1;
FIG. 3 is an enlarged elevation view, in section, through a hood
structure portion of the fluid handling system of FIGS. 1 and
2;
FIG. 4 is an enlarged elevation view, in section as indicated by a
dashed line enclosure, through a portion of the hood structure of
FIG. 3;
FIG. 5 is a plan view, in section along a line 5-5, through a
portion of the hood structure of FIGS. 3 and 4;
FIG. 6 is an elevation view, in partial section along a line 6-6,
through a portion of an air distribution box incorporated in the
fluid handling system of FIGS. 1 and 2; and
FIG. 7 is a perspective view, partially in phantom, of the air
distribution box of FIGS. 2 and 6 showing the flow of air
therewithin.
Referring now more particularly to the drawings, the present
invention is there illustrated in connection with a fluid handling
system for the circulation of air within a building structure. In
particular, a convenience food store or carryout building structure
such as is illustrated in FIG. 1 provides a particularly favorable
environment for the following disclosure of the present invention.
While the discussion hereinafter will proceed with particular
reference to the movement of air through such a closed building
space, it is to be understood from the outset that the means herein
disclosed for controlling the distribution of fluid flow along the
length of an elongate slot is contemplated as having utility with
gases other than air and with fluids other than gases. Further,
while the application of the present invention to handling of air
in conjunction with the operation of a carryout food service
business is particularly directed to conveying air suspended
materials, as pointed out hereinafter, it is contemplated that the
present invention has utility both with regard to conveying of air
suspended materials and with regard to the mere distribution of
fluid flow where applicable for other purposes. As illustrated in
FIG. 1, the structure incorporating the present invention includes
exterior walls 10 and 11 enclosing a space, a structural roof 12,
and an appearance ceiling 14 suspended below the structural roof
12. In the particular structure illustrated, a cooking grill 15 is
located adjacent the rear exterior wall 10, and a sandwich
preparation and delivery table 16 is located intermediate the depth
of the building. Customers enter through doors in the front
exterior wall 11, approach the delivery table 16 and order food
products prepared by grilling on the grill 15.
In order to provide a flow of air through the space enclosed within
the building structure, for removing therefrom smoke, airborne
grease particles, fumes or the like resulting from the operation of
the grill 15, the present invention includes an air handling system
as illustrated in FIGS. 2 through 7 arranged relative to the
building structure of FIG. 1. In particular, the air handling
system includes an air supply means generally indicated at 20 and
including an air distribution box 21 located adjacent the front
exterior wall 11 for supplying air into the interior of the
building and an air exhaust means generally indicated at 30 and
including a hood 31 positioned over the grill 15 for removing
smoke, airborne grease particles and the like from the interior of
the building. As indicated generally by arrows in FIGS. 1 and 2,
flow of air within the enclosed space is from the air distribution
box 21 forwardly against the interior side of the front exterior
wall 11, then turning to cross the food preparation and delivery
counter 16, pass above the grill 15 and into the hood 31.
In the form illustrated, both the air supply means 20 and the air
exhaust means 30 include fluid flow inducing means in the form of a
fan, respectively identified as a supply fan 22 and an exhaust fan
32. In both instances, operative communication is established
between the respective fans 22, 32 and a hollow casing defined
respectively by the air distribution box 21 and the hood 31 and in
each instance having an elongate sidewall. In the instance of the
air supply means 20, the air distribution box 21 is preferably of
generally square cross-sectional configuration, and has a length
appropriate to extend across at least a substantial portion of the
width of the store building in which the air handling system is
installed. The box 21 includes an elongate sidewall 24, arranged
facing the interior surface of the front building wall 11, which
has an elongate slot 25 opening therethrough. In the instance of
the air exhaust means 30, the hood 31 includes an elongate sidewall
34, facing rearwardly within the hood 31, with an elongate slot 35
formed between the lower edge of the sidewall and a turned under
portion 36 of the forward facing wall of the hood. While it is
contemplated that the grill 15 will extend substantially across the
entire width of the rear wall 10 in many installations of the air
handling system of the present invention, it is acknowledged that
the longitudinal extent of the hood 31 need only be substantially
the same as the width of the cooking area over which the hood 31 is
arranged.
Operative communication between the respective fans 22 and 32 and
the corresponding elongate hollow casings 21 and 31 is established
by coupling conduits 27, 28 and 38, respectively, directly
connected to and directly communicating with the elongate hollow
casings. In the instance of the air supply means 20, two
communicating conduits 27, 28 are provided, and preferably take the
form of spaced-apart round conduits each connected to a junction
box to which air is delivered from the fan 22. In the particular
installation shown, this arrangement has been chosen in order to
conserve space and facilitate ease of installation, and it is to be
understood that the configuration and arrangement of the
communicating conduits 27, 28 may vary. Similarly, the coupling
conduit 38 of the air exhaust means 30 is illustrated as a
generally rectangular duct, located centrally of the length of the
hood 31. It is to be understood that the present invention
contemplates that the coupling conduit for the hood 31 may be
connected thereto at a different point along its length and may be
subdivided into a number of coupling conduits if desired to
accommodate particular space requirements.
As installed in a convenience food store for the flow of air over
the grill 15, the air exhaust means 30 functions as a system for
conveying material by gaseous flow, in that the system is
particularly designed to convey grease particles suspended in the
air flow to and through the fan 32, to be delivered to a grease
collection or disposal means which forms no pertinent part of the
present invention. To accomplish the conveying function, the
elements of the exhaust means 30, including the fan, coupling
conduit 38, hood 31 and elongate slot 35 cooperate one with another
to maintain the velocity of fluid flow through all portions of the
exhaust system 30 from the slot 35 onward to the grease collection
or disposal means at least above that velocity at which grease
particles are maintained in suspension and move with the flowing
air. While particularly disclosed herein with reference to an
exhaust system, wherein a negative pressure is induced within the
hood 31, it is to be understood that the present invention
contemplates the maintenance of flow velocities at material
conveying levels to be equally applicable to other fluid flow
delivering systems, similar in some respects to the air supply
means 20, for the conveyance of materials to an elongate slot
outlet and the delivery of such materials through the elongate slot
outlet.
In both the air supply means 20 and exhaust means 30 of the present
invention, the volume of air flowing through the elongate slots 25,
35 is distributed in accordance with a predetermined profile along
the length of the slots. In the particular environment shown, it is
preferred that the distribution of air volume flow be uniform along
the entire length of the elongate slots, in an effort to obtain
uniform velocity of flow throughout the entire enclosed space
within the store. It is contemplated, however, that the
distribution of volume of fluid flow through an elongate slot may
be nonuniform therealong, if so desired, while relying upon the
structure now to be described to obtain such distribution.
In order to accomplish the distribution of flow through an elongate
slot in accordance with the predetermined profile, the present
invention incorporates baffle means within the hollow casings 21,
31 for directing the flow of fluid within the hollow casings along
predetermined paths. In particular, the baffle means within the
hollow casings cooperate with the casings in defining predetermined
open areas arranged to block fluid flow along the most direct flow
path otherwise existing between the elongate slot and the
communicating conduit means directly coupled to the casing, and to
divert the volume of fluid flow to certain other flow paths within
the casing. This mechanical forcing of the distribution of air is
accomplished, as discussed more fully below, generally by shaping
the open areas in generally triangular form. As trapezoidal
openings are frequently taken for purposes of flow analysis as
essentially triangular, and permit avoiding entanglement problems
in the conveying of fibrous materials, it is also contemplated that
the open areas may be formed as trapezoidal areas in fact and the
phrase "generally triangular" as used herein is intended to
encompass a truly trapezoidal area.
More particularly, the hollow casings of the distribution box 21
and hood 31 have predetermined cross-sectional areas, viewed
relative to the fluid flow therethrough. Baffle means disposed in
the casing have a cross-sectional area less than that of the
casings, so that predetermined open areas defined by the baffle
means and casing operate as tuned ports, as contrasted with the
substantially constant width along the slots 25, 35. While any
definition of the distribution of the open area for the tuned ports
would necessarily be very specific and relate only to a particular
design configuration, a general discussion of the manner in which
the distribution of open area in the tuned ports may be determined
will be included herein for purposes of full disclosure. In the
specific instance where the desired result is a substantially
uniform distribution of a volume of fluid flow along the length of
a slot the first step in the design of a baffle means is the
determination of the open area required in the tuned port to be
provided. This open area may be the same as the open area of the
elongate slot or may be other than that open area, depending upon
such factors as the desirability of maintaining uniform velocity
through the fluid handling system for the conveying of material,
the avoidance of sound such as whistling, or the plenum volumes
available within the divided hollow casing.
Once the required open area has been determined, that area is then
distributed in a predetermined manner proportional to the distance
of an incremental tuned port area from the communicating conduit
through which fluid will flow. In particular, the baffle means
functions to mechanically force distribution of the volume of fluid
flowing through the hollow casing into a predetermined profile
along the length of the slot, by causing fluid flowing within the
casing to turn in a direction substantially longitudinally of the
slot and then bleed through the tuned port area (see flow lines in
FIG. 7). Inasmuch as pressure and velocity distributions of such
flow longitudinally of an elongate slot are squared functions
reflecting losses encountered, the line defining the edge of the
tuned port area of the baffle means should, by mathematic
determination, be shaped in accordance with a squared function
relation, or be parabolic. However, where the slot through which
fluid is flowing becomes of substantial length, such as in an
excess of 5 feet, a parabola drawn between zero open area and the
required open area most remote from the communication conduit is
found to be essentially a straight line. Thus, the distinctions
between a parabolic edge for the tuned port and a straight line
edge of the tuned port may be ignored for certain applications.
Stated differently, as the tuned port opening approaches an
infinite aspect ratio, the parabolic curve defining an edge of the
tuned port opening becomes an essentially a straight line.
In an instance where the operative connection of a communicating
conduit means to a hollow casing is at a location other than the
center of length of the elongate slot, the above discussed approach
for distribution of tuned port open area still applies. However,
the total open area required is distributed on the two sides of the
communicating conduit means location in the same proportion as the
division of the slot area relative to a line through the
communicating conduit means center, where a uniform distribution of
a volume of fluid flow along the slot is desired.
Nonuniform distribution of the volume of fluid flowing through the
slot is obtained by variance from a squared function relation in
determining the distribution of tuned port open area relative to
the slot.
Referring particularly to the construction of the hood 31, it is to
be noted that the baffle means includes a horizontally extending
plate 39 disposed between the front and rear walls 34, 36 (FIGS.
3--5) and defining with the front wall 36 a pair of open areas 39A
and 39B. It is to be noted from FIG. 5 that the open areas 39A and
39B are so distributed relative to the position at which the
coupling conduit 38 directly communicates with the interior of the
hood hollow casing that the baffle plate 39 extends from the rear
wall 34 entirely to the front wall 36 in an area immediately
beneath the location of operative communication established by the
coupling conduit 38. This is done in order to divert fluid flow
from the shortest flow path which could be followed in the absence
of the baffle means, as mentioned above. Further, the portions of
the opened areas 39A and 39B more closely adjacent the location of
communication between the conduit 38 and the hollow casing are of
lesser width, thereby restricting the volume of flow in those
areas. The greater width of the open areas 39A and 39B at locations
more remote from the coupling conduit 38 results in greater volumes
of air flow passing through those areas. By the distribution of air
flow through the nonuniformly distributed open areas 39A and 39B of
the baffle means, the desired uniform distribution of the volume of
flow along the slot 35 of the hood 31 results.
Similarly, a baffle means including a baffle plate 29 is provided
within the air distribution box 21 of the air supply means. In this
instance, as shown in FIG. 7, the baffle plate 29 defines with a
wall of the box three open areas 29A, 29B and 29C with two closed
areas being provided directly beneath the communication of the two
coupling conduits 27 and 28 with the box 21. The configurations of
the open areas 29A, 29B and 29C are such that the volume of air
flowing through the port is distributed uniformly therealong, in
similarity to the result obtained with the hood as described
above.
It is to be noted that the above discussion illustrates obtaining a
desired predetermined profile of a volume of fluid flow through an
elongate port in one instance where the plenum volume upstream of
the port is minimized and in another instance where the plenum
volume downstream of the port is minimized. As to the air supply
means 20, the downstream plenum is the volume within the building
structure and is relatively large, while the upstream plenum is the
distribution box 21, which may be of minimum dimensions by
incorporation of this invention. In the air exhaust means 30, the
building structure volume provides an upstream plenum and the
downstream plenum within the hood 31 is minimized by incorporation
of this invention. Thus, the use of baffle means having a
nonuniformly distributed open area to divert and restrict flow
within a hollow casing is shown to be applicable regardless of the
direction of flow therethrough. Further, it is to be noted that
regardless of the direction of flow, the profiling of flow results
from blocking direct fluid flow along the shortest flow path
otherwise possible between the elongate slot and a communicating
conduit means while diverting fluid flow longitudinally of the slot
in a predetermined distribution.
In the drawings and specification, there have been set forth
preferred embodiments of the invention, and although specific terms
are employed, they are used in a generic and descriptive sense only
and not for purposes of limitation.
* * * * *