US3768394A

US3768394A - Device for producing dynamic flow in fluids to form curtains of the fluid

Info

Publication number: US3768394A
Application number: US00154526A
Authority: US
Inventors: J Powlesland
Original assignee: Powlesland Engineering Ltd
Current assignee: STONE CONWAY HUGHES & PARTNERS Inc; Desom Engineered Systems Ltd
Priority date: 1971-06-18
Filing date: 1971-06-18
Publication date: 1973-10-30
Anticipated expiration: 1990-10-30

Abstract

A fluid curtain generator according to the present invention comprising a generator for generating a high velocity stream of primary air and means for receiving the high velocity stream of air so as to mix the primary air with secondary air. The device also controls the rate of expansion of the thickness of the air curtain generated by mixing the primary and secondary air. The generator for generating the high velocity stream of primary air is preferably in the form of a conduit which is formed with a plurality of passageways opening outwardly therefrom. Mixing of primary and secondary air is achieved by passing the primary air through a venturi section and allowing it to expand in an expansion chamber while simultaneously inducing secondary air into the primary air stream. Preferably the primary air is directed between the venturi section formed at the inner end of a pair of guide plates arranged in a spaced relationship one on either side of the jet of primary air. The venturi section is spaced outwardly from the discharge of the primary air generator a distance sufficient to permit secondary air to be drawn in from the atmosphere on either side of the primary air stream. A closure plate may also be provided so that the atmosphere on one or other side of the venturi may be closed off to prevent secondary air being drawn into the venturi section from that side.

Description

United States Patent 11 1 Powlesiand 1 1 Oct. 30, 1973 DEVICEFOR PRODUCING DYNAMIC FLOW IN FLUIDS TO FORM CURTAINS OF THE FLUID [75] Inventor: John W. Powlesland, Woodbridge, Ontario, Canada [73] Assignee: Pdwlesland Engineering Limited,

Woodbridge, Ontario, Canada 22 Filed: June 18, 1971 211 Appl.No.:154, 526

[52] US. Cl 98/36, 239/419.5, 417/176 [51} Int. Cl F24f 9/00 [58] Field of Search ..417/176,190,151,

Primary Examiner-william E. W'ayner Attorney-Featherstonhaugh & Co.

[ ABSTRACT A fluid curtain generator according to the present invention comprising a generator for generating a high velocity stream of primary air and means for receiving the high velocity stream of air so as to mix the primary air with secondary air. The device also controls the rate of expansion of the thickness of the air curtain generated by mixing the primary and secondary air. The generator for generating the high velocity stream of primary air is preferably in the form of a conduit which is formed with a plurality of passageways opening outwardly therefrom. Mixing of primary and secondary air is achieved by passing the primary air through a venturi section and allowing it to expand in an expansion chamber while simultaneously inducing secondary air into the primary air stream. Preferably the primary air is directed between the venturi section formed at the inner end of a pair of guide plates arranged in a spaced relationship one on either side of the jet of primary air. The venturi section is spaced outwardly from the discharge of the primary air generator a distance sufficient to permit secondary air to be drawn in from the atmosphere on either side of the primary airstream. A closure plate may also be provided so that the atmosphere on one or other side of the venturi maybe closed off to prevent secondary air being drawn into the venturi section from that side.

14 Claims, 7 Drawing Figures 3,758,394 SHEET 10F 2 .PATENTEDUIIT 30 ms INVENTOR. JOHN w. POWLESLAND V Mal 4% ATTORNEYS I PAIENTEDUET 30 ms 3. 768 394 sum 2 OF 2 I N VEN TOR.

JOHN w. PowpEs BY ATTORNEYS DEVICE FOR PRODUCING DYNAMIC FLOW IN FLUIDS TO FORM CURTAINS OF THE FLUID FIELD OF INVENTION This invention relates to devices for producing dynamic flow in fluids to form curtains of the fluid. In particular, this invention relates to an air curtain generating device.

PRIOR ART Air curtains have been used as barriers to separate zones of different temperature, pressure and cleanliness. Air curtains have also been used to contain and convey contaminated atmospheres. Theadvantages in the use of an air curtain as opposed to a rigid divider wall are numerous. The air curtain permits ready access to the compartment which is closed off by the curtain due to the fact that it is possible for machinery or personnel to pass through the air curtain to gain access to the enclosure. In addition, an air curtain does not restrict the ability of an observer to observe the activities taking place in the enclosure.

Air curtains have been produced by air moving devices such as centrifugal fans, axial fans, air compressors and blowers used in conjunction with air ducts and pipes having slots or orifices arranged in a linear pattern corresponding to the required air curtain configuration.

A serious problem encountered with the conventional air curtain generators which incorporate fans is that in order to move a sufficient volume of air to form an effective air curtain, the fans and ducts must be relatively large and, as a result, they occupy an undesirable large space. The known devices which include blowers in combination with compressore are capable of producing air curtains which have high discharge velocities but they are relatively thin. The efficiency of an air curtain as a barrier to prevent the passage of heat, cold, dust, fumes or the like is related to the velocity and thickness of the air curtain. It has been established that the efficiency of anair curtain as a barrier is increased as the velocity is decreased and the mass and thickness is increased.

SUMMARY OF INVENTION The generator of the present invention overcomes the difficulties of the prior art described above and forms an air curtain of substantial thickness from a high pressure air discharge device.

According to an embodiment of this invention, a fluid curtain generator means comprises means for generating a high velocity stream of primary air and means for receiving said high velocity stream of air so as to mix said primary air with secondary air and control the rate of expansion of the thickness of the air curtain generated by the mixing of primary and secondary air.

According to a further embodiment of the present invention, a fluid curtain generator comprises means for generating a high velocity flow of primary fluid from a source of primary fluid and venturi means having an input end and an output end, the input end being in alignment with the primary fluid curtain so as to receive the primary fluid curtain. The input end of the venturi is spaced outwardly from the means for generating the primary fluid curtain such that the flow of primary fluid through the venturi induces a sufficient quantity of secondary fluid from the surrounding atmosphere to generate a fluid curtain of substantial thick ness which consists of a mixture of primary and secondary fluid of substantial volume.

PREFERRED EMBODIMENT The invention will be more clearly understood after reference to the following detailed specification read in conjunction with drawings wherein:

FIG. 1 is a pictorial view of a portion of an air curtain generator according to an embodiment of the present invention;

FIG. Ia is a view similar to FIG. 1 showing an alternative form of aperture;

FIG. 2 is a cross-sectional view of an air curtain generator according to an embodiment of the present invention; and

FIG. 3 is a plan view of an air curtain generator according to a further embodiment of this invention.

FIG. 4 is a cross-sectional view similar to FIG. 2 illustrating a still further embodiment of this invention;

' FIG. 5 is a pictorial view similar to FIG. 1 illustrating an alternative form of the invention; and

FIG. 6'is a partially sectioned pictorial view similar to FIG. 1 illustrating yet another embodiment of the invention.

With reference to FIGS. 1 and la of the drawings, the reference numeral 10 refers generally to an air curtain generator according to an embodiment of the present invention. The generator consists of a primary air supply header 12 and a pair of oppositely disposed plates 14 which serve to form the venturi throat and expansion chamber. The plates 14 are supported in an operative position by support arms 13 which are carried by or suspended from other supports (not shown) in a conventional manner. The reference numeral 16 refers generally to a closure plate used to .close one or other of the secondary air input passages as will be described below. A conduit 18 opens into the conduit 12 and the conduit 18 may be connected to a source of high pressure air such as a compressor 20 (FIG. 2) or a blower.

In FIGS. 1 and la of the drawings, two alternative types of apertures are shown formed in the conduit. The apertures 22 are in the form of longitudinally ex tending slots and the apertures 22a are in the form of substantially circular orifices. It will be understood that either one of these forms of apertures may be employed and the two alternative types are shown in FIGS. 1 and 1a of the drawings in order to illustrate possible alternative constructions. In a further alternative construction the slots could extend over the full length of the conduit. The apertures are proportioned and positioned so that when the conduit 12 is charged with high pressure air, the air will discharge through the

apertures

22 or 22a in the form of a thin, high velocity cur tain of primary air. a

As previously indicated above, the conduit formed with an arrangement of apertures suitable for providing a thin, high velocity curtain of air has previously been used. The principal problem with this construction is that the air curtain generated does not have a sufficient thickness or mass of controlled flow of moving air to form an efficient barrier. I

With reference to FIG. 2 of the drawings, it will be seen that the sheets 14 are disposed one on either side of the plane of the discharging primary air curtain. The plates 14 are disposed closely adjacent one another at a point spaced outwardly from the conduit 12 so as to form a venturi throat identified by the reference numeral 24, as shown in FIG. 1, the venturi throat extends longitudinally with respect to the conduit 12 in a spaced parallel relationship with respect to the discharge apertures 22,2241. It will be noted that the lower edges 14a of the sheets 14 are outwardly directed so as to form a co-anda surface intake leading to the throat. The lower edges of the sheets 14 are spaced from the surface of the conduit 12 so as to form a pair of oppositely disposed secondary air input passages 26 arranged one on either side of the plane of the primary air curtain. The closure plate 16 may be used as shown in FIG. 2 to close off one or other of the secondary air passages 26 as required in use. It will be understood that in generating an air curtain, it is frequently desirable to extract atmosphere from only one side of the curtain into the air curtain so that the curtain itself may be made up from the atmosphere of either of the two separated atmospheres. This construction can be extremely important when the air curtain is being used as a barrier to prevent the spread of obnoxious fumes or the like as it permits the user to regulate the flow of secondary air to ensure that the source of secondary air is either of the separated atmospheres. It will be apparent that the closure panel 16 may be used to close off either of the secondary air input passages as required. In certain installations, the problems involved in drawing the air off from one side or the other may not be acute with the result that the closure panel 16 may be dispensed with.

As shown in FIGS. 1 and 2 of the drawings, the plates 14 diverge in a direction away from the throat 24 so as to form an evase venturi expansion section. The proportions of the expansion section and the angle of inclination of the plates 14 relative to one another will be varied according to the type of installation and the required characteristics of the air curtain which is to be generated.

It will be understood that in many applications it may be necessary to provide an air curtain which is contoured to the configuration of the space which is to be enclosed. The device shown in FIG. 3 of the drawings is adapted to form an arcuate shaped curtain and it will be apparent that the arcuate configuration could be extended so that the device will generate a circular air curtain to form a self-contained enclosure. As shown in FIG. 3 of the drawings, a plurality of vanes 28 extend between the oppositely disposed walls 14 so as to subdivide the expansion chamber into a plurality of compartments. By dividing the large expansion chamber into a plurality of small enclosures, it has been found that an increased secondary flow of airis achieved.

Various modifications of the invention illustrated in FIGS. 1 to 3 of the drawings will be apparent to those skilled in the art. For example, as shown in FIG. 4 of the drawings, the header 12 maybe in the form of one or two independent headers 120, each being connected to a source of high pressure air by conduits 18a and each having primary air discharge passages 22b. In this embodiment, the secondary air input passage 26a is formed between the primary air input passages 22b. It will also be apparent that in certain instances the means for generating the curtain of primary air may be any of the known devices in use.

In the device illustrated in FIG. 4, the primary high velocity air may be made from one or other, or both, of the headers 12a as required in use.

A further modification of the present invention is illustrated in FIG. 5 of the drawings wherein a pair of plates 14 are connected directly to the conduit 12 and arranged one on either side of the path of the primary air stream emitted from the discharge passage 22. Each of the plates 14 is formed with a plurality of passageways 26b which open therethrough so that secondary air from the surrounding atmosphere will be drawn into the expansion chamber as a result of the passage of high velocity primary air through the expansion chamber. While this device provides for a less efficient mixture of primary and secondary air than that provided in the apparatus wherein the venturi is disposed outwardly from the outlet passage 22, it simplifies the mounting of the plates relative to the conduit 12.

A still further modification of the present invention is illustrated in FIG. 6 of the drawings wherein a single plate 14 is disposed to one side of the path of the stream of high velocity primary air. The plate 14 has an inner surface which is obliquely disposed with respect to the normal path of the stream of high velocity primary air. The stream of high velocity primary air is drawn against the surface of the plate 14 and secondary air from the surrounding atmosphere is mixed with the primary air to generate an air curtain which is a mixture of primary and secondary air. The single plate 14 also serves to control the direction of flow of the air curtain.

It will be apparent that while the preceding description of the preferred embodiment of this invention relates to an air curtain generating device, the device may also be adapted for use in creating a fluid curtain in other environments. For example, a device similar to that illustrated in FIG. 1 of the drawings could be submerged in the liquid fluid so as to generate a liquid curtain within the fluid so as to separate one fluid from another.

From the foregoing, it will be apparent that the present invention provides a simple and inexpensive apparatus for generating a fluid curtain of substantial thickness and mass.

I claim: I

1. An air curtain generator comprising means for generating a high velocity stream of primary air and venturi means for receiving high velocity curtain of air, said venturi means having a discharge axis extending perpendicularly from the throat of said venturi means, said venturi means being adapted to induce a sufficient quantity of secondary air into the primary air curtain from the surrounding atmosphere to provide an air curtain formed from a mixture of primary and secondary air, and guide means extending outwardly from said venturi means and diverging with respect to said discharge axis to provide controlled expansion of said air curtain.

2. An air curtain generator comprising, means for generating a high velocity stream of primary air, and venturi means having an input end and an output end and a discharge axis extending perpendicularly from the throat of said venturi means, said input end being disposed in alignment with said primary air stream so as to receive said primary air stream, said input end of said venturi means being spaced outwardly with respect to said means for generating said primary stream of air such that the flow of said primary air stream through said venturi means induces a sufficient quantity of secondary air from the surrounding atmosphere to provide an air curtain formed from a mixture of primary and secondary air, and guide means extending outwardly from said venturi means and diverging with respect to said discharge axis to provide controlled expansion of said air curtain.

3. An air curtain generator as claimed in claim 2 wherein said secondary air input passage means includes a pair of passages disposed one on either side of the longitudinally extending discharge passage of said header whereby secondary air may be drawn into said venturi throat from either side of the plane in which the air curtain is to be formed.

d. An air curtain generator as claimed in claim 3 including closure means for closing one or other of said secondary air input passages to prevent secondary air from being drawn in from one side or the other of said plane as required in use.

5. An air curtain generator as claimed in claim 2 including means for preventing the induction of secondary air from the surrounding atmosphere on one side or the other of said primary air curtain.

6. An air curtain generator comprising, means for generating a first high velocity curtain of primary air of a substantial length, a venturi throat forming means disposed in alignment with and spaced outwardly from said means for generating said first high velocity air curtain to receive a first curtain of air in use, said venturi means having a discharge axis extending perpendicularly from the throat of said venturi means, and secondary air passage means opening into said venturi throat forming means between said venturi throat and said means for generating said first air curtain whereby secondary air may be induced into said venturi throat by the passage of primary air through said venturi throat such that it discharges a curtain of air of substantial thickness consisting of a mixture of primary and secondary air, and guide means extending outwardly from said venturi means and diverging with respect to said discharge axis to provide controlled expansion of said air curtain.

'7. An air curtain generator as claimed in claim 6 wherein said guide means includes a pair of guide plates which form an expansion chamber extending outwardly from said venturi means whereby the rate of expansion of the thickness of the air curtain is controlled.

d. An air curtain generator as claimed in claim 6 including means for preventing the induction of secondary air from the surrounding atmosphere on one side or the other of said primary air curtain.

9. An air curtain generator comprising:

i a. primary air supply header means having a substantial length,

b. primary air input passage means opening into said header for connection to a source of high pressure air,

c. primary air discharge passage means opening outwardly from said header so as to permit a high velocity stream of air to discharge from said header over a predetermined length of said header,

d. venturi throat forming means having an input end disposed in alignment with and in a spaced parallel relationship with respect to said primary air discharge passage means of said header to receive high velocity primary air discharging from said primary header in use, said venturi throat forming means having an output end disposed to discharge along an axis perpendicular to said throat,

e. secondary air input passage means opening into said input end of said venturi throat forming means whereby secondary air may be drawn into said input end of said venturi throat by the passage of high pressure primary air therethrough to generate an air curtain which consists of a mixture of primary and secondary air,

f. and guide means extending outwardly from said venturi means and diverging with respect to said discharge axis to provide controlled expansion of said air curtain.

Ml. An air curtain generator as claimed in claim 9 wherein said guide means includes a pair of guide plates forming a pair of oppositely disposed outwardly diverging side walls extending longitudinally of said venturi throat and disposed one on either side thereof and a plurality of transverse vanes extending between said oppositely disposed walls in a spaced parallel relationship so as to subdivide said expansion chamber into a plurality of transverse compartments and thereby achieve a greater efficiency of induced flow of secondary air by increasing the ratio of induced airto primary air.

llll. An air curtain generator comprising:

a. primary air supply header in the form of a conduit of substantial length,

b. primary air input passage means opening into said conduit for connection to a source of high pressure air,

c. primary air discharge passage means opening outwardly from and extending longitudinally of said conduit over a substantial portion of the length of said conduit to permit a high velocity stream of air to discharge from said header in a predetermined plane in use, p

d. venturi throat and expansion chamber forming means consisting of a pair of oppositely disposed wall forming members disposed one on either side of the plane of the stream of primary air from said primary air discharge passage, said wall forming members being disposed closely adjacent one another at one end thereof to form a venturi throat, said wall forming members diverging in a direction away from said throat to form said expansion chamber, said venturi throat end of said walls being disposed adjacent to and in a spaced parallel relationship with respect to said conduit to form a pair of secondary air input passages arranged one on either side of said stream of air discharging from said primary air discharge passage means.

12. An air curtain generator as claimed in claim 11 including closure means for closing one or other of said secondary air input passage means to prevent secondary air being drawn in from one side or the other of said air stream.

13. An air curtain generator as claimed in claim 11 having a plurality of transverse vanes extending between said oppositely disposed wall forming members so as to subdivide said expansion chamber into a plurality of transverse compartments and thereby achieve an efficient induced flow of secondary air.

14. An air curtain generator as claimed in claim 2 including a source of high pressure air for generating said primary air curtain.

Claims

4. An air curtain generator as claimed in claim 3 including closure means for closing one or other of said secondary air input passages to prevent secondary air from being drawn in from one side or the other of said plane as required in use.

7. An air curtain generator as claimed in claim 6 wherein said guide means includes a pair of guide plates which form an expansion chamber extending outwardly from said venturi means whereby the rate of expansion of the thickness of the air curtain is controlled.

8. An air curtain generator as claimed in claim 6 including means for preventing the induction of secondary air from the surrounding atmosphere on one side or the other of said primary air curtain.

9. An air curtain generator comprising: a. primary air supply header means having a substantial length, b. primary air input passage means opening into said header for connection to a source of high pressure air, c. primary air discharge passage means opening outwardly from said header so as to permit a high velocity stream of air to discharge from said header over a predetermined length of said header, d. venturi throat forming means having an input end disposed in alignment with and in a spaced parallel relationship with respect to said primary air discharge passage means of said header to receive high velocity primary air discharging from said primary header in use, said venturi throat forming means having an output end disposed to discharge along an axis perpendicular to said throat, e. secondary air input passage means opening into said input end of said venturi throat forming means whereby secondary air may be drawn into said input end of said venturi throat by the passage of high pressure primary air therethrough to generate an air curtain which consists of a mixture of primary and secondary air, f. and guide means extending outwardly from said venturi means and diverging with respect to said discharge axis to provide controlled expansion of said air curtain.

10. An air curtain generator as claimed in claim 9 wherein said guide means includes a pair of guide plates forming a pair of oppositely disposed outwardly diverging side walls extending longitudinally of said venturi throat and disposed one on either side thereof and a plurality of transverse vanes extending between said oppositely disposed walls in a spaced parallel relationship so as to subdivide said expansion chamber into a plurality of transverse compartments and thereby achieve a greater efficiency of induced flow of secondary air By increasing the ratio of induced air to primary air.

11. An air curtain generator comprising: a. primary air supply header in the form of a conduit of substantial length, b. primary air input passage means opening into said conduit for connection to a source of high pressure air, c. primary air discharge passage means opening outwardly from and extending longitudinally of said conduit over a substantial portion of the length of said conduit to permit a high velocity stream of air to discharge from said header in a predetermined plane in use, d. venturi throat and expansion chamber forming means consisting of a pair of oppositely disposed wall forming members disposed one on either side of the plane of the stream of primary air from said primary air discharge passage, said wall forming members being disposed closely adjacent one another at one end thereof to form a venturi throat, said wall forming members diverging in a direction away from said throat to form said expansion chamber, said venturi throat end of said walls being disposed adjacent to and in a spaced parallel relationship with respect to said conduit to form a pair of secondary air input passages arranged one on either side of said stream of air discharging from said primary air discharge passage means.