US2801134A - Nozzle - Google Patents

Description

July 30, l957 F. J. NEUGEBAUR ETAL 2,801,134

NOZZLE Filed June 28, 1955 .nlll'llll Z 'I I lll.

f7 Ven or's 2U \\\\V l 00000000000000 0+ m L NozzLa Franz .1. Neugebauer, Schenectady, Edward L. Lustcnader and Robert W. Pdacauiay, Scotia, and Lee H. Tomlinson, Ballston Lake, N. Y., assignors to General ide-:tric Company, a corporation of New York Our invention relates to nozzles. More particularly, our invention relates to a nozzle of the vortex type which is particularly suitable for spraying relatively heavy or Viscous liquids.

Vortex nozzles for spraying liquids are Well known and have in the past taken varied forms in their production of a vortex or swirling mixed spray of liquid and air or oxidizer. A nozzle of this type typically comprises means for producing a swirling mass of air or oxidizer in a vortex chamber. The liquid is injected into the air vortex where it is atomized by the swirling air, the mixed air and liquid being discharged from the nozzle in the form of a `cone. While such a nozzle is generally suitable for liquids of lower viscosity, it has been found that it is incapable of providing requisite atomization for the heavier liquids such as Bunker C oil and the like even when the latter are pre-heated. lt has also been found that prior art nozzles are unsuited where a relatively narrow spray of high energy content is required. A relatively narrow spray is particularly important in combustors in which a wide fuel-air spray tends to cause the walls of the combustor to overheat and produces undesirable lcoking or carbon deposits because of spray and flame impingement.

An object of our invention is to provide a nozzle of the vortex type which will efficiently atomize relatively heavy or viscous liquids.

Another object of our invention is to provide such a nozzle which will produce a relatively narrow spray.

According to our invention there is provided a central vortex chamber into which primary air is angularly introduced to produce a swirling mass or vortex of air. Liquid `such as fuel oil is introduced into the Vortex chamber, the air causing the liquid to spread out on the charnber Wall in a thin, downstream progressing film. It is also necessary that the length of this vortex chamber be at least two or three times its diameter in order that a thin, uniform lilm of relatively viscous fluid may be formed on the wall thereof. Preferably the Vortex chamber is tapered slightly inwardly in a downstream direction so that the air vortex increases in rotational speed thus further tending to enhance the formation of a thin liquid film which is uniform in character. The fact that the liquid is introduced and formed into a uniform thin lm at a relatively cool point remote from the high temperature at the face of the nozzle enables it, in the case of fuel, more readily to become atomized by the secondary air without coking or carbonization. Secondary air is fed into an annular chamber which surrounds and is concentric with the central vortex chamber and has its outlet directed perpendicular or substantially perpendicular to the outlet of the central vortex chamber. Means are provided in the secondary air chamber just upstream of its outlet to impart a swirl to the secondary air with minimum pressure losses. By shaping the secondary air flow passages in an aerodynamically suitable way, a maximum of kinetic energy is imparted to the air jet issuing from the nozzle. The swirling vortex of high velocity secondary Patented July 30, 1957 air thus impinges upon the liquid film and primary air vortex atonn'zing the liquid and producing a relatively narrow spray with a high tangential velocity.

The features of our invention which we believe to be novel are set forth with particularity in the claims appended hereto. Our invention itself, however, both as to its organization and method of operation together with further objects and advantages thereof may best be understood by reference to the following description taken in connection with the accompanying drawing in which Fig. l is a general elevational view in cross-section of our invention. Fig. 2 is a perspective cut-away view of a portion of our nozzle. Fig. 3 is a cross-sectional plan View of our nozzle taken along the line 3 3 of Fig. 1, and Fig. 4 is a view of our nozzle taken along the line 4-4 of Fig. l. Fig. 5 is a sectional view at a reduced scale of a modied form of the vortex chamber of Figs. l and 2.

Referring to Fig. l, there is shown a nozzle 1 having a base 2 which receives the remaining component parts of the nozzle and is provided with a liquid feed conduit 3 and air feed conduit e. Fitted into the base 2 is a liquid injector 5 which is fixed to the base in any convenient manner as by the threading shown. A metal bound gasket 6 provides a seal between the base 2 and liquid injector 5. The single simple metal gasket insures trouble free operation for longer periods of time at low pressures than conventional high pressure nozzles having gaskets which deteriorate with heat or fuel contact. Fixed to the lower end of injector 5 is a screen 7 comprising va screen or filtering portion 8 and a rim 9, which latter is held in place by set screws itl. A central conduit 11 in the fuel injector serves to transmit liquid to holes 12 defined by the injector body which permit passage of fuel to be introduced into the vortex chamber. These holes are typically directed in a generally radial direction although their orientation can be changed as desired. These holes may be relatively large so that the fuel can be introduced at low pressures thereby improving pump life.

Surrounding and extending beyond the liquid injector 5 and also fitting into base 2 is a generally cylindrical part or sleeve 13 provided with spacer 14 at its lower end. A leakage path 3i is left between parts 5 and 13 in order that if fuel should leak 1"lrough gasket 6, it will enter the vortex chamber 16 harmlessly rather than passing into the air space d, clogging screen 23 or slots 2S. The nner wall of part 13 defines a cylindrically shaped central vortex chamber. The vortex chamber may be a true cylinder as shown at lo in Fig. 5, or preferably as shown at 16 in Fig. l, the vortex chamber is tapered inward gradually toward its outlet 17 or downstream portion. The outer wall of sleeve 13 is rounded inwardly as shown at 1S for reasons which will become apparent hereinafter. Holes or ports 319 for the injection of air into the vortex chamber 16 are provided through the wall of part 13 at its base or upstream end opposite or approximately opposite liquid injector holes l2. As best shown in Fig. 3, these holes are canted or tangentially arranged to cause air issuing therefrom to form a Vortex or swirl in vortex chamber 16, the air causing liquid introduced from holes l2 to form a thin, continuous film on the inner wall 0f the vortex chamber. Mounted around the upper portion of part 13 is a ring-like collar 2d unitary therewith or securely fixed thereto as by sweating or other usual means. The downstream inner portion of collar 20 is shaped to form an annulus 21 between it and the outer wall of sleeve 13 as shown. The upstream inner portion of the collar 29 adjacent part i3 is provided with a plurality of holes 22 which are typically cylindrical. The purposes of these holes 22 is evenly to distribute air fed into them, and to serve as a structural connection between the collar 20 and part 13. A cylindrical air screen or filter 23 is mounted onandiexitends between shoulder 24 of collarY Y and shoulder 25 of sleeve 13. This screen serves to lter air fed from conduit .4to protect the air holes 19 and theV air passages from large dirt particles in the air fed through conduit 4. s Y f i i In order to impart a vortex motion to secondary air passing through annulus 21, a deflector plate 26 is mounted downstream of and inrcontact with collar 20. The upstream side of plate 26 has an arcuate surface 27 which mates with the curved downstream Vouter surface 18 of sleeve V13 except for tangentially arranged or canted slots or grooves 28 which also have-a smooth arcuate base to minimize pressure loss and are spaced from sleeve`13 to provide channels-for the passage of secondary air. As will b e noted, plate i26 is closely spaced from the o utlet 17 of central vortex chamber Y16 so that air issuing therefrom willhave a relatively high velocity. The edge of plate 26 at its outlet is also relatively sharp as shown.

l The secondary air outlet is directed perpendicular or substantially perpendicular to the outlet of vortex chamber 16. The-downstream portion 29 of plate 26 is dished or flared outwardly. A cap suitably shaped and threaded or otherwise fixed to base 2 serves to hold plate Z6 and the other parts of the nozzle in place.

In operation air is fed through conduit 4 in the desired amount. This air passes through and is filtered by screen 23. A portion of the air hereinafter known as primary air passesY through-holesor ports 19 into vortex Y chamber 16. Since, as pointed out above, ports 19 are canted or are at an angle to the radius of the vortex chamber, the air passing therethroughV forms a downstream progressing vortex or whirling mass. Meanwhile liquid is fed through conduit 3 in desired amount and is filtered by `screen 7 in passinginto the chamber or Vconduit 11 in the fuel injector. From this chamber the liquid is fed through radially disposed holes 12. Upon entering the upstream portion of vortex chamber 16, the lliquid is picked up bythe whirling streams of air issuing from ports 19, causing theliquid'to form a thin, continuous film Vwhich clings to the inner wall of the vortex chamberand proceeds downstream. The downstream taper-V streams. A mere flowing of the liquid under low pressure is sufiicient. Neither are the sizes of holes 12 critical.

As pointed out above, a portion of the air entering conduit4 passes through ports 19 as primary air. The rest vof the entering air, known as secondary air, proceedsY downstream outside the vortex chamber. As this secondary air enters holes 22, its flow is evenly distributed. The air then enters the annulus 21 and thence passes through grooves 2S which, while maintaining a smooth flow, impart a vortex motion to the air of the same direction of rotation as the primary air. As the air passes through grooves 28, the passageway is also gradually restricted so that the secondary air issues from its outlet as a high energy vortex. Inasmuch as its outlet is just beyond the vortex-producing grooves 2S, there isrlittle or no Vturbulence in this secondary air as it issues. Upon issuing, the secondary air'impinges upon the vortex of primary air and upon the thin film of lquidas it breaks away from the Wall of the central vortex chamber effectively atomizing the liquid and counteracting the tendency of theliquid to spread under action of the primaryrair. Thus a relatively narrow .spray is achieved. The relatively sharp edge of plate 26 at the secondary air outlet prevents any tendency of the liquid to reform a film thereon Vor to form large liquid droplets.

Thereis provided by our invention a nozzle for atomizing liquids whi'chproduces a relatively narrow spray of theV Vorder of about 20460 degrees included angle which is most useful where awider spray cannot be tolerated.

4 t Our nozzle having no complex moving parts to get out of adjustment is particularly useful in combustors for gas turbine installations wherein the combustor has a relatively small diameter and the use of wide sprays tends to overheat the walls of the combustor causing them to fail and to carbonize or coleexcessiv'ely. The swirling of the atomized particles produced prolongs their residence in the flame zone to improve combustion performance.A

While our invention is suitable for spraying any liquids, it is particularly suitable for spraying relatively heavyV or viscous liquids which do not atomize readily upon merely impinging in a stream on a vortex of airY or gas. By causing the liquid first to be formed into a thin, continuous and uniform film in a vortex chamber be later acted upon-by an impinging vortex of high energy secondary air, the viscous liquid is effectively atomized.

In thosev cases in which the liquid is a viscous fuel, the introduction of the fuel at a point relatively remote from the hot face of the nozzle obviates coking or carbonization of the fuel which occurs when the fuel exists in a stream or relatively massive form near the nozzle face or outlet.

While we have described certain specific embodiments of Your invention, we wish it to be understood that we desire to protect in the following claims all changes or modifications` thereto which fall within the spirit and scope of those claims.

What we claim as new and desire to secure by Letters Patent Vof the United States is:

Yl. A nozzle for spraying a liquid comprising a member defining a central cylindrically shaped vortex chamber with an open end and a closed end and having ay smooth, continuous, imperforate side wall portion of an axial length substantially greater than its diametenlirst nozzle means for introducing liquid into the closed end portion of the vortex chamber, second nozzle means for Vintroducing primary air into the vortex chamber at the closed end thereof with a substantial tangential component whereby the liquid is caused to `form a thin, continuous, uniform downstream-progressing film of liquid on the Vvortex chamber wall, housing means defining an annular third annular nozzle means for directing an annular jetV of secondary air transversely across the liquid film issuing from the open end of the vortex chamber.

2. A nozzle for spraying a liquid comprising a member defining a central'vortex chamber with yan open en d and a closed end'and having an imperforate cylindrically shaped side wall portion of an axial length Vsubstantially ygreater than its diameter, first nozzle means for introducing liquid into the closed end portion of said vortex chamber in jets directed toward said side wall, second nozzle means for introducing primary air into the vortex chamber at the closed end thereof with a tangential component whereby the liquid is caused to form Va thin, continuous, uniform, downstream-progressing film of liquid on the vortex chamber wall, housing means defining an annular chamber surrounding and separated from the vortex chamber for the-passage of secondary air, third nozzle means for directing a jet of secondary air transversely .across the liquid film issuing from the open end of the vortex chamber, and means located immediately upstream from said third nozzle means for imparting a vortex motion to the secondary air of the same direction of rotation as the primary air.

3. A liquid spray nozzle having a member defining a centralvortex chamber with Va closed end and Yan open end and of a length at least equal to twice its diameter and having anrimperforate side wall portion tapered smoothly inwardly toward the open end, first nozzle means at'the upstream closed end of said chamber for introducing liquid into said vortex chamber in iets directed outwardly toward said tapered side wall, and second nozzle means at the upstream end of said imperforate side Wall for introducing primary atomizing air into said vortex chamber with a tangential component whereby the liquid is caused to form a thin, continuous, uniform, downstream-progressing lm on the smoothly tapered side Wall, housing means dening an annular chamber surrounding and separated from the vortex chamber for the passage of secondary atomizing air, third annular nozzle means communicating with said annular chamber and discharging said Secondary air across the path of the liquid film issuing from the open end of the vortex chamber, and means for imparting a vortex motion to said secondary air in the third nozzle means of the same direction of rotation as said primary air, said last-mentioned means being located upstream in said annular chamber from said third nozzle means whereby a smooth, solid swirl of secondary air impinges upon the thin lm of liquid and the vortex of primary air emerging from the open end of the vortex chamber.

4. A nozzle for spraying a liquid comprising a member dening a central vortex chamber with an open end and a closed end and having a smooth, continuous, imperforate side wall portion of an axial length substantially greater than its diameter, first nozzle means for introducing liquid into the closed end portion of the vortex chamber, second nozzle means for introducing primary air into the vortex chamber at the closed end thereof with a substantial tangential component whereby the liquid is caused to form a thin, continuous, uniform downstream-progressing iilm of liquid on the vortex chamber wall, housing means defining an annular chamber surrounding and separated from the vortex chamber for the passage of secondary atomizing air, .and third annular nozzle means for directing an annuissuing from the open end of the vortex chamber.

Anthony Apr. 10, 1923 Buckland May 6, 1952

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