US2296314A - Diffuser - Google Patents

Description

Sept. 22, 1942; F. L. SLADE DIFFUSER Filed Aug. 3, 1940 5 Sheets-Sheet 1 p 22, 1942 F. SLADE- 2,296,314

DIFFUSER 'Filed Aug. 3, 1940 5 Sheets-Sheet 2 FQ L. sLADE r 2, 96,314-

' DIFFUSER r I Filed-Aug. 5/1940 5Sheets-Sheet4 Sept- F. L. SLADE 2,296,314

DIFFUSER Filed Aug. 3, 1940 5 Sheets-Sheet 5 Patented Sept. 22, 1942 UNITED STATES PATENT OF FlCE 'azaam V V We. 8 :23 0. Application August 3, 1940, Serial No. 350,953

, 13 Claims. The invention described herein may be manufactured and used by and for the United States Government for governmental purposes without the payment to me 'of any royalty thereon.

This inventionv relates to the art of ventilation and has moreparticularly to do with methods and apparatustfor discharging or. diffusing air or other conditioning gases or vapors into the ambient atmosphere of an enclosure, such as a marine vessel, a vehicle, or. a room of a building.

The principal object of the invention is to provide new and improved devices and methods for the introduction and diffusion of ventilating or conditioning gases into the ambient medium, with such acontrol of the velocity and direction or flow of the introduced-gas as to substantially reduce or eliminate noise and to obtain a thorough and rapid mixing-and scrubbing eifect without giving rise to undesirable drafts in the habitable portions of the enclosure being ventilated or .conditioned.

Basically, the invention involves the discharging of a gaseous fluid into the ambient medium in such a way as to set up a return flow in the resulting mixture of ambient and introduced gases, whereby a proportion oi these gases is returned into or adjacent the outlet orifice of the discharging or difiusing member or nozzle, and then redischarged and-recirculated in the enclosure, thus effecting a very eflicient mixing or. scrubbing action between the two fluids.

Prior proposals looking toward the attainment of similar eflects have been made, but these have necessitated the provision of mechanical means such as a plurality of overlapped or periorated walls or vanes to provide a kind of injector device, and these expedients have not proved to be as efiicient or as tree irom noise and drafts as the comparatively simple arrangements which characterize the present invention.

- The fundamental provisions of the invention include a substantially cylindrical discharge or diffuser member into which the incoming venti lating or conditioning medium is introduced tangentially from the supply duct which traverses the building or other structure carrying the in-' stallation. This tangential introduction of the gas creates a whirling, constantly expanding, hollow, conical jet of fluid, which, due to the novel arrangement and proportioning of the device under the principles. of the invention, sets up a vortex movement which of itself induces the eflicient return flow and scrubbing action, with a substantial reduction in noise and draft, and

whereby a fluid in the liquid phase is discharged M into an ambient gaseous fluid such as the atmosphere, as, ior example, in the case of lawn sprinklers 'and the like. It has also been proposed to discharge a rotating stream of air into the atmosphere of an enclosure through a narrow elongated cylindrical outlet member, either at a relatively constant high velocity or at an increasing velocity through a continually contracting system; the only objective being to iorce the air into the chamber or enclosure in the ttorm of an ordinary rotary jet, which is obviously of some slight advantage over a straight line introduction of the fluid. Such a proposal, howevenindicates .no conception oi the principles oi the present invention, nor does it involve the novel qualifications and structural'limitations which the applicant has determined by much experimentation as being necessary in producing the effects described.

As will be developed in detail as the description proceeds, it is necessary in order to attain the return flow scrubbing effect by means of the fuser member bear a ratio to that of the outlet orifice thereof which will fall within certain limits. If the discharge cylinder is too long with ,respect to its diameter, the desired. vortex will disappear (as, indeed, will the rotary flow itself if the length is inordinately increased) and ii the length of the difiuser is too short, the air will spill over the rim of the diffuser before the whirling is efiectively initiated.

If the normal outflow is unobstructed, the vortex will be formed within the mouth 0! the outlet orifice of the discharge member or diffuser, and the velocity, of the air as measured across any diameter of the orifice will be at a maximum adjacent the periphery where an annular outflow section is observed; then at the inner margin 01 this annular section, a point oLzero velocity is found; and within this circle of zero velocity, the velocity of air within the plane of the orifice is found to be negative, 1. e., an aspiration of air from the enclosure is taking place. This inwardly moving air is mixed .with the treating air from the supply duct and is again discharged through the annular peripheral portion of the orifice.

The invention in its preferred form contemplates the provision of a cylindrical discharge,

element having an inlet connection of either constant or increasing rectangular cross section; but within the broad scope of the invention may be included discharge elements of somewhat frustoconical shape, or those having round bottom portions; and the inlet sections may also be of circular or elliptical cross section.

By positioning certain diverting elements at the circle of zero velocity adjacent the plane of the orifice, certain variant eifects in the direction of flow of the introduced air may be attained without destroying the vortex and aspirated return flow, and these features are also comprised within .the scope of the invention.

Another object of the invention is to provide in the diffuser members, novel control dampers and operating means therefor, certain embodiments employing two or more dampers permitting the mixing of a plurality of different treating media in a single diffuser.

Other objects of the invention include the provision of diffusers having inclined outlet orifices, and others having outlet orifices at both ends of the cylinder; and also various combinations of the diffuser members with lighting fixtures whereby not only an improved ornamental effect is attained, but also certain structural, functional, and utilitarian features result.

Other objects and features of novelty will be apparent from the following specification when read in connection with the accompanying drawings in which certain embodiments of the invention are illustrated byway of example.

The present application is a continuation-inpart of my copending application Serial No. 204,636, filed April 27, 1938.

In the drawings:

Figure 1 is a view in horizontal cross-section of a portion of a ventilating duct with a simple form of outlet member or diffuser embodying the principles of the invention, attached thereto;

Figure 2 is a view in side elevation of the same structure;

Figure 3 is a view in side elevation of a doubleended diffuser;

Figure 4 is a similar view of a difiuser having an inclined outlet orifice:

Figure 5 is a fragmentary view in vertical section of the outlet end of a difluser showing a grille having a diverting blade attached thereto;

Figure 6 is a view in vertical section of a diffuser of the practical commercial form having a damper of novel type applied thereto;

Figure 7 is a bottom plan view of the diffuser shown in Figure 6, with a portion of the outlet grille broken away;

Figure 8 is a fragmentary sectional view taken substantially on line 8-48 of Figure 6;

Figure 9 is a vertical sectional view through a diffuser member having two inlets and associated damper controls;

- Figure 10 is a fragmentary horizontal sectional view of the diffuser shown in Figure 9;

tary views similar to Figure 10 but showing adjusted positions of the two dampers;

Figure 13 is a vertical sectional view of a diffuser having a plurality of inlets occupying different planes;

Figure 14 is a bottom plan view of the same device with a portion of the outlet grille broken away;

Figures 15 and 16 are vertical sectional views showing modified forms of diffuser cylinder, and outlet vanes;

Figure 17 is a view in side elevation of a diffuser having a frusto-conical body portion;

' Figure 18 is a vertical sectional view showing a diffuser in which a lighting fixture and damper control are combined; and

Figure 19 is a fragmentary sectional view taken on'line l9i9 of Figure 18.

Referring now more particularly to Figures 1 and 2 of the drawings, in which an elementary form of the invention is illustrated, it will be seen that the supply duct is indicated generally by the reference numeral Ill. The discharge or dlfiuser member attached to the duct is designated i2 and is provided with the short, tangentially disposed inlet conduit l5. In this embodiment the inlet conduit is of a rectangular cross-section and is secured to the supply conduit it at the junction of the larger portion l6 and the continuing portion ll of diminished section and capacity. The duct I0 is of the velocity type, but a plenum type of supply duct may be employed if desired. The inlet section I5 is attached to the duct and aligned with the duct in such a manner that a portion of the air flowing through the duct is cut on from the main How of air and caused to flow in a direction parallel to the main flow in the duct and thereby diverted into the cylin ri l part of the diffuser tangentially thereto'so as to set up a spiral whirling or rotation of the air within the diffuser. The remaining air flowing through the supply duct i'ii continues through the section I! to the next point of take-oil whereupon another portion of the delivered gas is passed tangentially into the next difiuser along the line, with a corresponding diminution of dimensions of the supply duct.

The delivered air or gas rotates helically about the interior of the diffuser l2 and passes outwardly of the circular orifice 20 of the diffuser in the form of a constantly expanding cone of rotating gas of continually diminishing velocity. The outgoing cone of gas is indicated diagrammatically at 25 in Figure 2 of the drawings and the section of the diffusing jet of gas is indicated by the same reference numeral in Figure 1.

The whirling cone of delivered gas sets up a vortex within the interior thereof which results ity. outwardly of this circle the newly intro- Figures 11 and 12 are diagrammatic fragmen- 7 duced gases and the recirculated gases are being discharged in the expanding hollow cone, and within this neutral circle the introduced gases and aspirated portions of the surrounding medium are being returned toward the outflow orifice.

Although the general direction of flow of the Velometer readings at terminal face of diflusef;

readings and may fluctuate between reasonable panding taper.

form of the invention selected at random. Alon the diameter W! at the oriflce plane 2| of the i difluser II, are the stations 1,; 2.3, 4, and 5. Sim-n ilarly, along the diameter YZ are corresponding: ly disposed stations 1. 2, 3, 4, and station 3 be--v ing common to both diameters. The tabulation shows the velometer at dlflerent points, is a positive reading indicatin outflow of gas and a negative reading the inflow. m values given are in ieet per minute. 7

V inlet velocity 1890 F. P. M.

I Diameter Diameter '1 +1150 +1750 2 GG) -550 3 -660 --6(Xi 4 -d0() -6) s +1850 +1800 The condition of the gases within the room or enclosure adjacent the diffuser may be determined irom the following tabulation in which similar average velometer readings are given for the test stations 10-16 inclusive as shown in Figure 2 of the drawings. The test stations were selected at approximately two and one-half feet from the orlflce 20, stations 12 and 14 being directly below the margins of the diffuser; stations 11 and 15 being at somewhat less than 30angles from the adjacent stations 12 and 14 respectively; and stations 10 and 16'being just outside of the 30 line.

Average oelometer readings at points spaced from outlet of difiuser m 0 l1 +150 12 1'4 14 so 15 16- 0 As indicated, these values represent average 5'5 limits, but they clearly follow the pattern suggested by the description and the illustrations.

It has been found by extensive experimentation that in order. to attain this return flow effect and its consequent valuable scrubbing action between the introduced gas and the ambient fluid, with a minimum of noise and draft, the entire discharge system from the mouth of the inlet member I! to the point of furthest movement of the introduced air should be of exthat is, the velocity. of the fluid should diminish continually with a corresponding expansion in the olume or capacity oi the system. It has been determined that the physical characteristics of the'dlfluser, in order to attain this result, should fall within the follow- I oi gasset by the difluser aretically indlcatedinthe drawings.

len h oi the diiluser i to its diameter should lie between 0.75:1 and .2:1,'and this ratio should never exceed 3:1.

The deleterious eiiects oi exceeding the upper and lower limits or these ratios may be explained as follows. when the proper "taper of the diffuser system is upset by the provision of a 7 too shallow cylinder, the tangentially introduced gas will spill over the margins of the outlet oriflce II between the points Y'and Z. in the counterclockwise direction as yiewed in Figure 1, before the proper whirl or helical rotation within .the diiluser-is attained. This, of course, will destroy the vortex and aspirating eilect. It the ratio of the outlet area to the' inlet area is too small, the outlet velocity will be too high, and

the only result will be the introduction of the gas into the ambient fluid in the form. 0! a narrow whirling solid cone; and it the height or length oi the difl'user is too'great with respect to the diameter, the whirling eii'ect will be lessened and ii the length were continued to an excessive degree, this eflect would flnally disappear and a straight longitudinal flow of air would result. a

The principles of the invention which involve the mixing eflect just described, may be embod-- led in various. modifications, one of which is shown in a somewhat elementary form in Figure 3 or the drawings in which the difluser cylinder 40, led by the inlet section ll, is open at both ends inorder to provide two discharge cones A2 at either endo the device. It will be immediately apparent that in the case of this doubleoriflced cylinder, the best ratios 0! length to di- 'ameter will be approximately double those already stated in connection with the single outlet embodiments. It is obvious that in all of the embodiments illustrated and described, the direction of discharge may be upwardly, downwardly, or horizontally in any direction, according to the nature of the enclosure and the particular eflect desired. 7

, In Figure 4 of the drawings, there is illustrated a diffuser cylinder 45 in which the oriflce plane 48 is inclined with respect to the axis of the diffuser, with the result that an inclined discharge cone and vortex indicated at 48 is iormed.

By the provision of suitably shaped and positioned bailies or vanes, the expanding discharge cone may be altered in order to widen it and flare the stream of introduced'fluid toward a plane parallel with the outlet plane. For example, it may be desirable,.when the diffuser is returnflow of gases. At the circle of zero velocity between the discharging and returning gases,

an outwardly flared vane or baiile 55 is secured to the grille 5| or made integral therewith. This curved bame tends to flare or widen the cone of discharging gases as indicated by the arrows, without disturbing the aspirating effect of the arrangement at all. It will be understood that the arrows in Figure 5, and also in certain of the other figures, indicate the general direction of flow .of the bodies otfluid which, however,

1 have a rotating or circular movement within themselves.

In Figures 15 and 16 0! the drawings, other modifications ofthe difluser are shown which also employ bailles such as indicated in Figure 5. In Figure 15, acylindrical diffuser body I is illustrated, having an inlet passageway SI of rectangular cross-section. The flared vane I2 has the same general effect on the flow of introduced fluid as the vane 55 in Figure 5. This device is not provided with a grille, however, and the vane 62 is secured to the body it of the diffuser as by means of the rods or bolts 64. Conical baffle 65 is secured to the bame 62 as by means of the supports 66 and is so shaped as to conform approximately to the natural lines of flow of the returning or aspirated fluid. The baflle 65 is designed, however, to aid in streamlining the return flow and prevent the accidental formation of eddy currents, and may also be so positioned as to prevent the return of the fluids to a very great extent into the mouth of the diffuser.

In Figure 16 of the drawings the cylindrical shape of the diffuser it is modified to some extent to form a bowl like or rounded bottom portion ii, and the inlet connection I2 is of circular cross-section conforming generally to the curvature of the portion ll. Otherwise the outlet structure is exactly the same as that shown in Figure 15.

As heretofore suggested, the shape of the diffuser body need not be exactly cylindrical, and the frusto-conical shape of the diffuser shown at E5 in Figure 17 of the drawings conforms more nearly to the theoretical, constant expansion or "taper" of the diffusing system. This diffuser is fed by an inlet connection It which is, of course, shaped to conform to the surface of the diffuser body.

In order to control the flow of gas introduced into the diffuser, suitable damper arrangements are provided. One eminently satisfactory embodiment of this control means is illustrated in Figures 6, 7, and 8 of the drawings. The diffuser body in this case is indicated by the numeral 8E3, and, for convenience in manufacture, may be pressed from a single sheet of metal. The margirl of the diffuser is flanged as at 8! and a stamped grille 82 may be secured thereto as by means of the screws 83. Centrally of the grille 83 there is provided an opening through which the control shaft 85 for the arcuate damper plate 86 may pass. The inner end of the shaft 85 is rotatably secured within the perforated saddle bearing strip 87. Extending from spaced points along the inner portion of the shaft at are the tubular portions 80 of the telescoping strut members st. These members also include the rods ti which are received within the tubes b8 and have their outer ends rigidly secured to the damper plate 86. A coil spring ts extends between the damper and the end of the tubular member 88 in order to urge the struts 99 toward extended.

position and press the damper plate 88 firmly against the inner surface of the diffuser. The inlet section @5 of the diffuser is arranged tangentially and forms with the surface of the member $8 a rectangular opening 96. The area of the damper 86 is, of course, sufllcient to overlap the margins of this opening.

Upon the outer end of the control shaft d5 there is secured a handle M0 for rotating the damper element. Within the confines of the grille 82 there is rigidly secured to the shaft 86 a radial arm IOI which is designed to cooperate with stop elements secured to the grille 82 in either direction. The central portion of the grille 02 is provided with an arcuate slot It: as most clearly shown in Figure 8 of the drawings, and at the proper points along this slot are secured the bolts I as by means of the nuts I. The inwardly extending shanks III! of the bolts extend across the plane of rotation of the arm Ill and prevent its movement beyond the points at which the stops are secured. The stop members are so positioned as to permit the damper to swing from the open position shown in solid lines in Figure 7 of the drawings to the closed position indicated in dotted lines.

The grille 82 in this embodiment is provided with a plurality of openings H0 through which the fluids may pass in their inward and outward directions as heretofore described. The central solid portion of the grille is provided with a cover plate or a cap ill and a spring washer H2 is disposed between this cap and the handle portion I00. By means of this damper element, the flow of fluid may be entirely out off, or any degree of opening provided.

In some cases it is desirable to supply a plurality of fluids to an enclosure, these fluids having different properties as relate to temperature, humidity, etc., and in Figures 9-14 of the drawings there are illustrated certain embodiments of the invention including provisions for the introduction of gases from two diflerent sources and having different properties, into a single diffuser or outlet arrangement.

In the embodiment illustrated in Figures 9-12 inclusive an outlet structure is provided for attachment to superposed ducts, the diffuser body :26 being provided with tangential inlet connections I22 and 826, both having openings upon the same side of the difiuser body and being provided withdampers designated, respectively, by the numerals I25 and lit. A grille H8 is applied to the outlet orifice of the diffuser I20 and passing axially therethrough is the control shaft I30 which has a bearing i3l for its inner end. A pair of struts 832, corresponding exactly in construction and function to those illustrated at 90 in Figures 6 and 7 of the drawings, are provided adjacent the inner end of the control shaft m. Surrounding the shaft I30 is the tubular shaft G35 which extends for approximately half the length of shaft H30. Struts I36 similar to those shown at I32 extend from this tubular shaft I35 tothe damper E26.

Pinned to the shaft H30 adjacent its outer end,

is the bevel gear Mt which is continually in mesh order to.limit the movement of the damper in with the bevel pinion Mi which is carried by the bracket I42 secured to the grille i28. Another bevel gear M4 is adjustably secured to the tubular shaft. I35 as by means of the set screw I45. Relative rotation of the tubular member and the gear I is prevented, by means of the pin E46 secured to the gear M4 and working in the slot provided in the tubular shaft 835, when the set screw M5 is released for the purpose of sliding the gear Md along the tubular shaft I35 in order to adjust the relative positions of gears ME, I, and M4. Any desired initial relative setting of the two dampers H25 and MS may be attained by the adjustment of the gear hi l with relation to the stationarily supported gear MI by means of the adjusting devices just described, and it is obvious, by manipulation of the handle 50 secured to the end of the operating shaft I30,

will be completely closed, and any intermediate v proportioning of flow through the two inlet ducts between these extreme positions can be attained. In Figure-1O of the drawings the damper I28 is shown in its open position and the other damper 5 inlet conduits. Figure 12 illustrates a position I I88 in. which both dampers are closed. This position may be attained by a suitable relative adjustment of the controlling shafts.

' In the embodiment illustrated in Figure 13 of the drawings, the two supply ducts for the difl ferent introduced fluids are disposed in the same plane and the inlet conduits I88 and IN are applied to'the diffuser shown in Figure 14.

I82 at different angles as The openings I84 and I88 from these conduits into the diffuser m are spaced peripherally of the surface of the diffuser and are controlled by the dampers I81 and I88 which are fixed in their relative positions since the telescoping spring pressed struts I'III are rigidly secured to the control shaft I12. The con- ,trol shaft is operated by means of a handle I14 "and passes through the outlet grille I18 in the usual way. Both dampers are shown in closed position in Figure 14 and it is obvious that by rotating the 'handle I14 in a clockwise direction as seen in Figure 14, the opening I88 from the duct I8I,wi1l be uncovered and the damper I81 will move from the opening I84 in the duct I88. when the rotation is continued so that the damper I88 closes the duct I88, flow will occur 7 having a free and unobstructed open end comfrom the duct I8I. Further rotation ofthe combined dampers will open both ducts for an equal mixture of the two fluids. Still further movement in the same direction will cause the damper I81 toclose the duct III and the duct I88 will be supplying the fluid to the difluser. By adjustment to suitable intermediate positions a, desired proportion of the two fluids may be attained.

Certain embodiments of the invention-may be combined with lighting fixtures and novel adaptations of the control means for the diffuser for I this purpose may be arranged. In Figures 18 and 19 of the drawings, an embodiment is illus-- trated in which the difluser I88 is set into the ceiling of an enclosure which is indicated at I8I.

An inlet duct I82 supplies fluid to the diflus'er and the inlet opening is controlled by means of the damper I84. Disposed centrally of the diffuser is a tubular rod or pipe I88 upon the outer end of which is carried an electrical socket I88 into which a light bulb I" may beplaced. The pipe I88 is rigidly secured to the base of the diffuser I88 as by means of the nut I88, and may also serve to hold the diffuser I88 in its position by securing it to the outlet box I88. A tubular member I82 is disposed axially of the difluser I88 and carries. the spring pressed extensible struts I84 which support and operate the damper I84.

28I which is supported by means of the washer 282 held in place by the nut 288 which is applied to the rod I85. The member I82 is centered with respect to the rod or shaft I85 by means of the disc 285 which is provided with an opensaid This tubular member is flared at its outer end as shown at I88 and is provided with a trans- 5 288 carried by the rod 288. ,This'shoe moves along the inner surface of the member I80 and serves to balance the pressure of the damper I84.

Obviously the rotation of the light casing I92, I88, I81, serves to adjust the damper I84 and a limiting device is provided for stopping the rotation at its fully opened and closed positions. As more clearly shown in Figure 19 of the drawings, an arm 2I8 is secured to and extends radially from the rod I85, and adjustably secured to the disc 288 carried by the member I88 are the angle brackets 2I2 and 2, which are fastened to the disc 288 by means'of the bolts 2I5. The slots 2I8 permit of a limited adjustment of these stop brackets 2I2 and 2I4 for determining the fully open and fully closed positions of rotation of the combined light fixture and damper control.

It is understood that various changes and alterations may be made in the embodiments illustrated and described herein without departing from the scope of the invention as defined in the following claims. It is also understood that the terms gas, air, and gaseous medium are used interchangeably and are intended to include vapors within their scope.

Having thus described the invention, what is claimed as new and desiredto besecured by Letters Patent is:

1. In a ventilation system, an outlet structure for distributing air or other gaseous fluid into an enclosure with the substantial elimination of noise and draft, said structure comprising an unobstructed inlet conduit, a cylindrical member prising the discharge orifice of the "structure, inlet conduit being disposed tangentially with respect to the perimeter of said cylindrical member, and communicating therewith, said cylindrical member being of a length equal to from about threequatters to not over three times its diameter, all whereby the fluid is caused to swirl within said cylindrical member and to flow from said discharge orifice in a spirally conical form for a predetermined distance, and a portion of said flow being automatically diverted in- .wardly toward the center of the cone and back toward said discharge orifice to again join the continued substantially conical flow of introduced fluid.

2. In a ventilation system or the like, an outlet and diffusing structure for introducing a'gaseous fluid into an ambient gaseous medium and mixin the same. with the substantial elimination of noise and draft, said structure comprising an unobstructed inlet conduit, a hollow substantially cylindrical member having an open end comprising the discharge orifice of the structure, said inlet conduit being disposed tangentially with respect to the periphery of the cylindrical member and opening into the latter, said cylindrical member being of a length equal to from threequarters to two times its diameter, and the crosssectional area of the said outlet orifice being from three to five times that of the inlet end of the inlet conduit, and there being no diminution of cross-section within thestructure from the last named point toward the outlet orifice, all whereby the fluid is caused to swirl within the substantially cylindrical member and to flow from said discharge orifice in an expanding spirally conical form for a distance from said orifice, and a portion of said flow and of the ambient medium ing 288 through which the rod passes. The membeing automatically diverted inwardly toward the center of the cone and back toward said discharge orifice to again join the continued substantially conical flow of introduced fluid.

3. In a ventilation system or the like, an outlet and dimrsing structure for introducing a gaseous fluid into an ambient gaseous medium and mixing the same, with the substantial elimination of noise and draft, said structure comprising an unobstructed inlet conduit, a hollow substantially cylindrical member having open ends comprising the discharge orifices of the structure, said inlet conduit being disposed tangentially with respect to the periphery of the cylindrical member and opening into the latter, the double-orificed cylindrical discharge member being of a length equal to from one and one-half to four times its diamstar, and there being no diminution of crosssection within the structure from the last named point toward the outlet orifices, all whereby the fluid is caused to swirl within the substantially cylindrical member and to flow from said discharge orifices in an expanding spirally conical form for a distance from said orifices, and a portion of said flow and of the ambient'niedium being automaticallydiverted inwardly toward the center of each cone andback toward the corresponding discharge orifice to again Join the continued substantially conical flow of introduced fluid.

4. In a ventilation system or .the like, an outlet and diflusing structure for introducing a gaseous fluid into an ambient gaseous medium and mixing the same, with the substantial elimination of noise and draft, said structure comprising an unobstructed inlet conduit, said inlet conduit being of circular cross-section, a hollow substantially cylindrical member having a closed end, and an open end comprising the discharge orifice of the structure, the corners adjacent the closed ends of said substantially cylindrical member being rounded to correspond to .the radius of curvature of said inlet conduit, said inlet conduit being disposed tangentaliy with respect to the periphery of the cylindrical member and opening into the latter at said rounded corner, said cylindrical member being of a length equal to from about three-quarters to not over three times its diameter, and there being no diminution of sesame fluid is caused to swirl within the substantially cylindrical member and to flow fromsaid-discharge orifice in an expanding spirally conical form having an annular cross-section lying adjacent the periphery of'the outlet orifice, and a portion of said flow and of the ambient medium being automatically aspirated inwardly of said orifice within the discharge cone to rejoin the outward substantially conical'flow of introduced fluid, thus providing a circle. of zero velocity between the discharge and aspiration zones of said orifice, andan outwardly flared annular vane cross-section within the structure from said inlet fluid into an ambient gaseous medium and mixing the same, with the substantial elimination of noise and draft, said structure comprising an unobstructed inlet conduit, a hollow substantially cylindrical member having an open end comprising the discharge orifice of the structure, said inlet conduit being disposed tangentially with respect to the periphery of the cylindrical member and opening into the latter, said cylindrical member being of a length equal to from about three-quarters to not over three times its diameter, and there being no diminution of crosssection within the structure from said inlet end carried by said cylindrical member and disposed at said circle of zero velocity for flattening and broadening said cone of discharged fluid without interfering with the described aspiration phenomenon.

6. In a ventilation system or the like, an outlet and diflusing structure for introducing a gaseous fluid into an ambient gaseous medium and mixing the same, with the substantial elimination of noise and draft, said structure comprising an unobstructed inlet conduit, a hollow substantially cylindrical member having an open end comprising the discharge orifice of the structure, said inlet conduit being disposed tangentially with respect to the periphery of the cylindrical member and opening into the latter, said cylindrical memher being ofa length equal to from about threequarters to' not over three times its diameter, and there being no diminution of cross-section within the structure from the last named point toward the outlet orifice, all whereby the fluid is caused to swirl within the substantially cylindrical member and to flow fromsaid discharge orifice in an expanding spirally conical form having an annular cross-section lying adjacent the periphery of the outlet orifice, and a portion of said flow and of the ambient medium being automatically aspirated inwardhg of said orifice within the discharge cone, thus providing a circle of zero velocity between the discharge and aspiration zones of said orifice,'an outwardly flared annular vane carried by said cylindrical member and disposed at said circle of zero velocity for flattening and broadening said cone of discharged fluid without interfering with the described aspiration phenomenon, and a conical bailie also carried by the cylindrical member and disposed adjacent the central portion of the plane of the outlet orifice and having its apex directed outwardly toward the center of the aspiration zone.

- 7. In a ventilation system or the like, an outlet and diflusing structure for introducing a gaseous fluid into an ambient gaseous medium and mixing the same, with the substantial elimination of noise and draft, said structure comprising an unobstructed inlet conduit, a hollow substantially cylindrical member having an open end comprising the discharge orifice of the structure, said inlet conduit being disposed tangentially with respect to the periphery of the cylindrical member and opening into the latter, said cylindrical member being of a length equal to from about threequarters to not over three times its diameter, whereby the fluid is caused to swirl within said cylindrical member and to flow from. said discharge oriflce in a spirally conical form, and a portion of said flow being automatically diverted inwardly toward the center of the cone and back toward said discharge orifice to rejoin the outward substantially conical flow of introduced fluid, and means for controlling the flow of fluid from said.inlet conduit to said substantially cypoint toward the outlet orifice, all whereby the lindrical member, said means comprising an arcuate damper of an area suflicient to cover the opening between said members, and disposed within said substantially movement against the inner thereof, operating means for said damper, and spring pressed means for urging said damper radially outwardly against the wall of said member.

8. In a ventilation system or and diffusing structure for introducing a gaseous fluid into an ambient gaseous medium and mixing the same, with the substantial elimination of noise and draft, said structure comprising an unobstructed inlet conduit, or hollowsubstantially cylindrical member having an open end comprising the discharge oriflce of the structure, said inlet conduit being disposed tangentially with respect to the periphery of the cylindrical member and opening into the latter, said cylindrical memher being of a length equal to from about threequarters to not over three times its diameter, whereby the fluid is caused to swirl within said cylindrical member and to flow from said discharge orifice in a spirally conical form, and a portion of said flow being automatically diverted inwardly toward the center of the cone and back toward said discharge oriflce to rejoin the outward substantially conical flow of introduced fluid, and means for controlling the flow of fluid from said inlet conduit to said substantially cylindrical member, said means comprising an arcu-' ate damper of an area sufllcient to cover the opening between said members, and disposed within said substantially cylindrical member for sliding movement against the inner surface of the "wallthereof, an axially disposed, rotatable operating shaft, an extensible and contractible strut projecting-radially from said shaft and support-- ing said damper on its outer end, and means for resiliently urging said damper radially outwardly against the surface of the wall of said member.

9. In a ventilation system or the like, an outlet and diffusing structure for introducing a gaseous fluid into an ambient gaseous medium and mixing the same, with the substantial elimination of noise and draft, said structure comprising 'a subcylindrical member for sliding surface of the wall comprising. the discharge orifice of the structure, a plurality of inlet pamageways leading into said f member tangentially thereto through openings in the wall thereof which are spaced longitudinally of the member said cylindrical member being of a length equal to from about three-quarters to the like, an outlet I not over three times its diameter, whereby the fluids are caused to swirl within the substantially cylindrical member and to flow from said discharge orifice in an expanding spirally conical form, and a portion of said flow being automatically diverted inwardly toward the center of the cone and back'toward said discharge oriflce toreioin the outward substantially conical flow of introduced fluid, arcuate dampers for controlling the flow of fluid through said openings, operating means for moving said dampers about the inner surface ofthe wall of said member to open, clou, and adjust said openings for the desired proportioning of fluid entering said memher and discharged therefrom, and means for resiliently pressing said damper against said wall surface, said operating means including a rotatable actuating element and gearing connecting said element with each of said dampers for movement in opposite directions.

11. In a ventilation system or the like. an outlet and diffusing structure for introducing a gaseous fluid into an ambient gaseous medium and mixing the same, with the noise and draft, said structure comprising a subthe member said cylindrical member being of a stantially cylindrical member having an open end comprising the discharge oriflce of the structure, a plurality ofinl'et passageways leading into said member tangentially thereto through spaced openings in the wall thereof said cylindrical memberheingofalengthequaltofromahoutthreequarters to not over three times its diameter,

whereby the fluidsare caused to swirl within the substantially cylindrical member and to flow from said discharge oriflce in an expanding. spirally conical form, and a portion of said flow being automatically diverted inwardly toward the center of the cone and back toward said discharge oriflce to rejoin the outward substantially conical flow of introduced fluid, arcuate dampers for con-- trolling the flow of fluid through said openings" operating means for moving said dampers about the inner surface of the wall of said member to open, close, and adjust said openings for the desired proportioning of fluid entering said member and discharged therefrom, and means for resiliently'pressing said damper against said wall surface. g

10. In a ventilation system or the like, an outlet and diffusing structure for introducing a gaseous fluid into an ambient gaseous medium and mixing the same, with the substantial elimination of noise and draft, said structure comprising a substantially cylindrical member having an open end '15 fluid,

I fluid into an ambient length equal to from about three-quarters to not over three times its diameter, whereby the fluids are caused to swirl within the substantially cylindrical member and to flow from said discharge orifice in an expanding spirally conical form, and a portion of said flow being automatically diverted inwardly toward the center of the cone and back toward said discharge orifice to rejoin the outward substantially conical flow of introduced fluid, arcuate dampers for controlling the flow of. fluid through said openings. operating means for moving said dampers about the inner surface of the wall of saidmembertoopen,close,andad- Just said openingsforthedesiredproportioning of fluid entering member and discharged therefrom, and means for resiliently pressing said damperagainst said wall surface.

12. In a ventilationsystemortheiike, anoutlet gaseous ing the same,'with the substantial elimination of noise and draft, said structure comprising an unobstructed inlet conduit, a hollow substantially cylindrical member having an open end comprisingthe dischargeoriflceofthestrucuimsaidinlet conduit being disposed tangentially with respect to the periphery of the cylindrical member and opening into the latter, said cylindrical memberbeingofalengthequaltofromahoutthreequarters to not over three times its diameter, whereby the fluid is caused to swirl within said cylindrical member and to flow from said discharge oriflce in a spirally conical form, and a portion of said flow being automatically diverted inwardly toward the center of the core andback toward said discharge oriflce to rejoin the outward substantially conical flow of introduced substantial elimination of stantially cylindricalmemberhavinganopen end and means for controlling the flow of fluid ate damper ofan area suilicient to cover the opening between said members, and disposed within said substantially cylindrical member for sliding movement against the inner surface of the wall thereof, a hollow casing containing a source of light disposed axially within said cylindrical member and rotatable with respect thereto, an extensible and contractible strut projecting radially from said casing and supporting said damper on its outer end, and means for resiliently urging saiddamper outwardly against the surface of the wall of said member.

13. In a ventilation system, an outlet structure structed inlet conduit, a cylindrical member haifing an open end comprising the discharge orifice of the structure, said inlet conduit being disposed tangentially with respect to the perimeter of said for distributing air or other gaseous fluid into an enclosure with the substantial elimination of noise and draft, said structure comprising .an unobcylindrical member, and communicating therewith, said cylindrical member being of a length equal to from about three-quarters to about one times its diameter, all whereby the fluid is caused to swirl within said cylindrical member and to flow from said discharge orifice in a spirally comcal form for. a predetermined distance, and a portion of said flow being automatically diverted inwardlytoward the center of the cone and back toward said discharge orifice to again Join the continued substantially conical flow of introduced fluid,

' LSLADE.

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