US 1506904 A
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Description (OCR text may contain errors)
Sept. 2 1924. 1,506,904
B. S. HARRISON EQUALIZED DISTRIBUTION SYSTEM FOR FLUIDS Filed Nov. 23 1921 Patented Sept. 2, 1924.
UNITED STATES PATENT OFFICE.
BURT S. HARRISON, OF CHICAGO, ILLINOIS, 'ASSIGNOR TO DRYING SYSTEMS, INC., OF CHICAGO, ILLINOIS, A'CORPORATION OF ILLINOIS.
\ EQUALIZH) DISTRIBUTION SYSTEM FOR FLUIDS.
Application filed November 23, 1921. Serial No. 517,308.
To all whom it may concern:
Be it known that I, BURT S. HARRISON,
a citizen of the United States of America,
and a resident of Chicago, county of Cook,
and State of Illinois, have invented a new livery or receiving conduits or nozzles, and
- of such deliver is illustrated herein in a manner which is useful for the uniform delivery of air to or exhaust of air from a room throughout its length. In the dryin art it is necessary in order to attainuni orm results upon all the goods in the drying room, to obtain a uniform circulation of air through the room at all points, that is, each unit of length of the room should be subject to the same rate of air flow as every other such unit.
The objects of the present invention are to improve and simplify the construction or exhaust conduits in order to insure t e desired result and eliminate the necessity of adjustments of any kind.
When fluids such as air or gas are caused by a fan or blower, to flow through a duct having distributed outlets, it has generally been found difficult to so duct and its inlet or outlet orifices or nozzles to attain a uniform distribution or flow at all points. This difiiculty is quite pronounced when using the customary arrangement of stepped duct, that is, one having reducin or transformation portions between t e various outlets along the same. Unless the friction which will occur in each outlet and each transformation is exactly known there is a likelihood that the outlets nearest the fan will over-deliver, and to obtain even distribution requires the use of numerous dampers, and considerable testing and adjustment is also required. This trouble becomes particularly apparent when long ducts having a great number of openings are employed. If the openings are proportioned throughout according to the frictional resistance, then no two such openings will be of the same size. Also, the shape and proportion of the transformation links, and the angle at which the outlet branches project from the duct greatly affects the resistance.
proportion the The objects of the present invention are accomplished by a structure such as illustrated in the drawings, wherei'n Figure 1 is a plan view of a delivery duct constructed according to this invention to deliver a continuous sheet of air of uniform thickness.
Figure 2 is an end View of the same.
Figure 3 shows the duct in side elevation.
Figures 4, 5 and 6 are similar views, but illustrate a duct of circular cross section rather than the rectangular duct illustrated in Figures 1 to 3.-
Figures 7, 8 and 9 illustrate a duct similar to the one shown in Figures 1 to 3, but is designed with particular reference to exhausting rather than delivering air.
The present design of duct may vary considerably in cross sectional appearan e, but for convenience of fabrication is preferably either square or round as illustrated. Its
principal characteristic feature is that it is pered throughout its length in a manner corresponding to the variationin the duct dimensions. The apron is supported, by partitions or withes regularly spaced, and extending from the front to the back edge of the apron. This apron affords means for uniformly varying the resistance to the flow of the air or other fluid at the outlets, and in complementary correspondence to the resistance encountered at various points throughout the length 'of the duct so that the resultant pressure at the outlet (velocity head) is the same for every unit of outlet len h.
he present design takes into consideration the various losses in pressure due to dynamic action and friction. The dynamic losses are the velocity head or power to cause the. fluid to enter the duct, losses due to change of direction, and losses due to chan of velocity as in transformation. The fraction losses are all due to the friction of the fluid against the walls of the duct. Pressure, temperature and density of the air effeet the losses, but in the same duct system these need not va The pressure loss due to dynamic action is of course much affected tion or velocity, the less the loss. With this in mind, the present duct is uniformly tapered from end to end, and from the fact that the friction losses vary directl with the len th of the duct, inversely as t e diameter of t e duct, and directly as the square of the air velocity, the frictional resistance arranged for at different points along the length of the duct by the apron is made to complement these losses to insure equal deliveries at different points throughout the length of the duct. In this manner by an extremely simple design, uniform delivery with respect to both volume and-velocity at different points along the length of the duct is insured.
As illustrated in Figures 1 to 3, the delivery duct may be formed from sheet metal, with the rectangularly arranged walls 1, 2, 3, and 4:, these walls being of radually decreasing width so as to provi e the desired taper. The wall 4 at its rear edge 5 terminates short of the wall 1, to provide the outlet opening 6. The edge 5 of the wall 4 is turned over the wire 7 to eliminate vibration and avoid a sharp edge around which the air must travel in its change of direction between the duct and the outlet 8. This outlet is covered by an'apron 9 attached to the wall 1 and extending parallel with. the wall 4, and uniformly s aced outwardly therefrom. The outlet 8 1s subdivided by equally spaced partitions 10 between the apron 9 and the wall 4,
In the tapered form of duct as illustrated, the velocity of'fiow through the slot 8 may be of constant value throughout the length of the duct, or if desired, adually and uniformly diminished from t e large end to the small end. This is due to the'fact that the frictional resistance within the duct gradu ally increases from the large end to the small end of the duct since frictional resistance in the duct varies inversely as the diameter and directly as to length of the duct. By properly proportioning the width and taper of the apron, and its distance from the wall 4, the outlet friction can be made to supplement the duct friction in any desired way.
At the large end of the duct in the form shown in Fig. 1 the duct friction is least and the outlet friction is greatest due to the length (width) of the apron, just as friction in any duct varies with the length of the duct. At the small end of the duct the duct friction loss is greatest due to its small diameter and distance from the fan, but the outlet friction loss is least because the apron is shortest (narrowest) at this point. The sum of the duct friction loss and the outlet friction loss is the same at an point along the length of the duct, and as the area of the outlet is uniform per unit of length, the delivery of the different units of len h of the outlet will be the same as to hot volume inlet area and velocity throughout the length of the duct. It may be seen that the dimensions of the duct if designed according to the present plan may be readily correctly determined for any desired result.
The frustoconical duct or nozzle illustrated in Figures 4 to 6 is designed according to the sameplan, tapering from end to end and providing frictional resistance at the outlets which complements the frictional resistance at-the corresponding portion of the duct. This form may be rolled from a single sheet of metal, giving the spiral cross sectional appearance illustrated in Figure 5, the outlets 11 being arranged for by the overlapping ends 12 and 13 of the body part 14:.
The outlets are separated by the spacers 15.
The exhaust duct shown in Figures 7 to 9 is similar in design to the delivery duct illustrated in Figures 1 to 3 except that its taper is less, and the apron 16 while tapering in correspondence with the duct, is spaced in inclined relation to the duct the s ace being gradually narrowed toward the arge end of the duct. When air is being delivered from the duct by pressure, the taperon the duct may be greater than when the air is being exhausted through the duct, on account of the develo ment of static pressure in the duct, that 1s,.
the velocity in the duct can be maintained practically uniform throughout the duct in a pressure distributing system but in an ally increases toward the larger end of the duct. This may be allowed for in dimensioning the duct. The duct may be tapered less but the width of the inlet slot and the distance of the apron from the side of the duct may be uniformly tapered so that the er unit of length willbe progressively ecreased toward the fan, thereby maintaining substantially the same vol ume of inflow per unit length of duct, the velocity of flow being highest at the end nearest the fan, and lowest at the end farthest from the fan, and being progressively and uniformly varying at points between.
The formula for the calculation of the. equalized outlet duct is based on the theoretical velocity of fluid, which is eight times the sqpare rootof the head in feet. Followin .t heid at a velocity of eight feet per second. For gases under average local conditions, 29.9" barometric pressure and 60 F temperature, the theoretical velocity in feet per is law, water flows with a one foot mula has a coefficient of efllux which is based on actual experience. The equalizer outlet duct comprises a converging pipe in which the coeificlent varies from 9/10 to .99,
- diameter. The maximum head and velocity in the duct is at the supply end of the duct. The velocity of delivery at the large end of the duct is reduced to the same velocity as that at the small end of the duct by the proviio n of suitable resistance along aslotted' outlet. In this construction, the static pressure does three separate things which are almost exactly equal in pressure value. One part or 1/3 provides the velocity head for actual slot de ivery. One part overcomes the friction in a conver ing pipe with a length times the duct diameter, and 1/3 of the static pressure changes the direction of the flow of the air from the duct to the slotted outlet around a thin sheet. Since the pressure lost by friction varies from zero at supply end to a maximum of 1 at the small be altered or omitted 'without departing from the spirit of this invention asv defined by the following claims.
p I claim:
1. A duct of the class described uniformly tapered lengthwise and provided with a longitudinal slot for sidewise flow of fluid,
and an apron extending along and over said slot, being spaced from the walls of the duct and tapering in width to provide va ry1ng local friction complementing the frictlon n -the duct to insure substantially the same sidewise flow of the fluid for the diflerent units of length of the duct.
- 2. A duct of the class described uniformly extending lengthwise of the duct, an apron extending along said slot but spaced from the walls of the duct and tapering in width in correspondence with the taper of the duct,-
and transverse partitions between said apron and the wall of the duct.
3. A duct of the class described uniformly varying as to carrying capacity from end .len end, and the pressure lost by friction in the to end thereof, and a walled outlet extending along the s de of the duct to provide for sldewise flow of fluid into or out of the duct,
.the walls of said outlet varying in area from end to end of the duct to resist the flow of fluid in order to compensate for the varying static pressure and carryin capac- .1ty of the duct at different points a ong its length, and thereby insuring a uniformly .distributed flow of fluid through the side for the iflerent units of length of the duct.
5. A distributing duct having a longitudinal slot, a wall extending from the side of the duct along said slot and varying in width from end to end of the slot to provide local resistance to sidewise flow, proportioned in complementary relation to the static pressureshin the duct at different points of its 6 A distributing duct, havinga longitudmal slot for sidewise distribution of fluid, and an apron extending along the duct adjacent the slot, overlapping and spaced from the wall of the duct and shaped to provlde local resistance to sidewise flow proportloned in com lementary relation to the static pressures in the duct at different points of its length, thereby insuring substantially the same sidewise flow of fluid for the different units of length of the duct.
7. A distributing duct, having a lon itudinal slot for sidewise distribution of fluid,
and an apron extending along the duct adjacent the slot, overlapping and uniformly spaced from the wall of the duct and sha ed' to provide local resistance to sidewise fibw proport oned in complementary relation to the statlc pressures in the duct at different points of its length, thereby insuring substantially the same sidewise flow of fluid for the different units of length of the duct.' 8. A distributing duct, having a longitudinal slot for sidewise distribution of fluid,
and an apron extending along the duct adjacent the slot, overlapping and uniformly spaced from the wall of the duct and gapered toconform'with the taper of the uct.
9. A distributing duct, having a longitudinal slot of uniform width for sidewise distribution of fluid, and an apron extending along the duct adjacent the slot, overlapping and uniformly spaced from the wall of theduct and tapered to conform with the taper of the duct. v
10. A distributing duct, having a longi-' tu dinal slot for sidewise distribution of fluid, same sidewise flow of fluid for the diiierent an apron extending alon the duct adjacent units of length of the duct, and flow direct- 10 the slot, overlapping an spaced from the ing partitions in the space between said well of the duct and shaped to provide local apron and duct wall.
resistance to sidewise flow proportioned in Signed at Chicago this 18th day of complementary relation to the static pres- N0vember1921. sures in the duct at difierent points of its I length, thereby insuring substantially the BURT S; HARRISON.