US2942790A - Air-atomizing liquid spray nozzle - Google Patents

Description

June 28, 1960 N. E. STARKEY 2,942,790

AIR'ATOMIZING LIQUID SPRAY NOZZLE Filed Jan. 25, 1959 5 XZQ) /J /i ,4 I TI E 42 m ,'/4 A1 '1 yr!" I! 47 "/2 lnvenfors Neal E. Sfarkey fll/en F. Pierce by The/r fillorney United a s Patent G YAIR-ATOMIZING LIQUID SPRAY NOZZLE I of New York Filed Jan. 23, 1959, S'er. No. 788,677

3 Claims. (Cl. 239-405) This invention relates to nozzles for atomizing a liquid and more particularly to an improved air-atomizing and spray jet arrangement in :a nozzle for spraying relatively heavy or viscous liquids. t

In efforts to improve the operating economy of a device utilizing liquid fuel for combustion such as a gas turbine engine, consideration has been given to the less expensive residual oils as opposed to the distillate oils. These residual oils, since they represent the residue from the cracking process, are relatively heavy having a high viscosity and a high degree of impurities. in order to achieve eflicient combustion, the liquid fuel must e atomized to a fine mist and is often sprayed into the combustion chamber in the form of acone so as to mix intimately with the incoming combustion-supporting air.

The viscosity of the fuel is a rough index of the ditiiculty which will be encounteredin atomizin'g the fuel, and in order to effectively atomize 'the lowgrade residualoils such as Bunker C oil, a very efficient nozzle is necessary. Many previous nozzles for this purpose have employed intricate and complex passageways which are difficult to machine and which are subject to carbonization due to the inherent high level of impurity or residue existing in a residual oil.

Due to the complexity of some of the prior art atomizing nozzles, difficulty has been encountered in re-designing a given, nozzle for a new size and shape combustion chamber to provide a suitable cone spray angle and droplet size which is elficiently matched to the combustion chamber.

Accordingly, one object of the present invention is to provide an improved fuel nozzle which is particularly adapted to atomizing and spraying viscous fuels.

Another object is to provide a simple and inexpensive replaceable one-piece fuel nozzle core which is easy to manufacture and to maintain in service.

A further object is to provide an improved arrangement for introducing the fuel into the gaseous atomizing stream, which reduces carbon deposition on the nozzle.

According to the invention, a series of circumferential: ly spaced passages, which are skewed with respect to the central axis of the nozzle, furnish a series of diverging jets of atomizing fluid from the faced the nozzle which have a tangential component. -A second series of passa es, diverging as the elements of a cone from the central axis, intersect the first series to'inject fuel at a point adjacent the intersection of the firstseries with the face of thenozzle. This arrangement results in an improved atomizing arrangement in which the fuel enters the atom.- izing stream at a high angle of entry and mixing is effected extremelyclose to the face of the nozzle, thereby reducing carbonization of the fuel within the nozzle body itself.

The features of the invention which are believed to be novel are set forth with particularity in the claims appended hereto. The invention itself, however, both as to its organization and method of operation together with further objects and advantages thereof may best be under- 2,942,790 Patented June 28, 1960 stood by reference to the following description taken in connection with the accompanying drawing in which:

Fig. 1 is a longitudinal sectional drawing showing the complete nozzle assembly;

Fig. 2 is an enlarged front view of the nozzle face;

Fig. 3 is an enlarged .fragmental view in section of the tip portion of the nozzle core taken along lines 33 of Fig. 2; and I V Fig. 4 is an additional fragmental side view of the nozzle core tipportion, taken along lines 4-4 of Fig. 2. .Referring now to Fig. l, the nozzle core, shown generally at 1-, is held-in thenozzle body 2 by means of a cap 3 which is secured to the nozzle body 2 by threads 4, The nozzle body 2 is cast to include a supporting arm 2a which defines a fuel inlet conduit 5 and an atomizing fluid inlet conduit 6. The nozzle body 2 also includes a generally cup shaped portion 2b defining radial shoulders 2c which,-a1o ng with similar radial shoulders 3a on the cap 3,- serve to hold the-nozzle core 1 in position. The nozzle core -1 has extending flange portions 1a and 1b which hold the nozzle, core 1 in axial and radial position as the cap 3 is screwed into the nozzle body 2. A heat. resistant gasket 7., :perhaps of a copper-asbestos material, separates the radial portions 1a and 20 to form an effective seal between the -fuel and the atomizing fluid.

A fuelstrainer -8 is situated in a suitable recess is at the-rear of thecore and the liquid fuel entering from inlet conduit 5 flows through strainer 8 and along the central conduit 9 which extends along the-central axis of the nozzle c'o're'l. The atomizing fluid, on the other hand, enters through inlet'conduit 6 into a cavity 11 which is defined by-the exterior of-the n'ozzle core land the nozzle cap-3.

Figs. :2, 3, and 4 show the-arrangement of the fuel and atomizing jets in the tip portion of the nozzle core 1, which is the subject'of this invention. The flange portion 1b of the nozzle core 1 has drilled therein a series of 'circumferentially spaced passages 12. Each of the passages -1'2;-has its axis ina straight line 'which is skewed or non-coplanar with the central axis 13 of the nozzle core. :Pass'ages 12-are drilled so that they provide openings inthenozzle core 1;between the inner radial surface lcand the'outer radial surface 1d of the flangeportion 1b. The-skewed passages 12 are preferably arranged with equal circumferential spacing about the central axis 13 so astoprovide a uniform distribution of atomizing fluid. Since-the passages 12 are skewed ornon-coplanar with the-centralaxis, they will enter the radial faces 10 and 1d at an angle so as toform ellipses 12a, 12b at the points of intersection. It should also be apparent from the drawing'jofFig. Z-that a "circle, having its center on the central axis 13,whi'ch is de'scribed'through the series of ellipses 12a, lying on the surface 1c may have a larger radius than a similar circle described through the series of ellipses 12b lying on the face 1d of the nozzle core. This is due to the fact that the skewed axes may have a closer point of approach to the central axis 13 in the vicinity of face ldthan they do near'face :lc. This-point of closest approach betweenjthe skewed axes and the central axis should preferably be located near the face 1d in order to enable the nozzle core to have the smallest dimensions possible-consistent with-'aagiven size spray cone- This may be seen more-clearly by referring to Fig. 4 where it is apparent that --decreasing .projected angle A willalso decre'asethe spray angle and increasing projected angle A will require a larger nozzle flange 10. Fig. 4 also shows that the atomizing fluid issuing from port 12 will diverge from the central axis and Fig. 2 will illustrate that'the'diverging .j'et will also have a tangential component. Thus skewed ports 12 furnish a simple structure for providing awidespray angle-from arelatively small nozzle core.

the central axis 13, terminates short of the face 1d of the nozzle core. A series of passages 14 intersecting conduit 9 are drilled so that their axes converge toward the central axis 13. In the preferable embodiment of our'invention, these passages are equal in number to the skewed passages 12 and have their axes coplanar with the central axis 13 so as to intersect axis 13. These passages 14 serve to subdivide the fuel entering conduit 9 and to discharge the fuel into the atomizing jet at a point which lies closely adjacent the face 1d of the nozzle core.

The method of drilling passages 14 in the onepiece nozzle core is shown by the fragmental portion'of a drill bit 15 in Fig. 3. The bit 1 may clearthe edge of the nozzle face 1d at point '16 and clearance 17 may be prov'ided also to afford a surface for drilling. Theoretically, optimum performance would be achieved ifjclearance 17 fuel into the atomiz'ing fluid did not'exist, but due to thepractical considerations of the possibility of damage at this critical juncture, manufacturing variation, and the possibility of heat concentration at the sharp edge, some small clearance'is preferred. Owing to the fact that drill bit 15 must pass through the opening 12b of passage 12 in order to drill port 14, it I will be seen that a projection of the side walls of port 14 upon the plane containing the face surface In will result in an ellipse lying within the ellipse 12b formed by passage 12. It will also be appreciated that. for this reason, even in the absence of a jet of atomizing fluid passing through passage 12, a pressurized fluid issuing from passage 14 would substantially 1 avoid impinging upon the opposite Wall of passage 1'2. The how of an atomizing fluid through passage 12 insures, however, that the possibility of such fr'npingement is negligible. This avoidance of contaminating the passages -of the nozzle tip portion with fuel is very important in reducing the formation of large droplets and reducing carbonization and deposition of impurities on the nozzle since any portion of the nozzle where an exposed liquid filmof fuel is subjected to heat will be subject tocarbonization and deposition. v i Y It will also be observed thatthe mixing of'the fuel with the atomizing fluid does not take place within the body of the nozzle, but tends to occur substantially in the plane of the nozzle face 1d. 'Since the mixing is initiated very close to the face of the nozzle core and proceeds rapidly away from the core, a very effective arrangement for substantially reducing carbonization and deposition is realized. 7 r r I Another very important consideration in the effective atomization of a highly viscous fuel is the angle of entry of the jet of fuel which is injected into a jet of atomizing fluid, the angle of entry being measured from the axis of the atomizing jet. The greater the angle of entry into the atomizingfluid, the more efiective will be the automization. To this end, the arrangement of atomizing fluid and fuel passages disclosed will provide a veryhigh angle of entry between the fuel jet and the atomizing jet, 'in a very small dimensioned nozzle core.

As an example of this, a very effective spray nozzle which willeject atomized fuel in approximately a-hollow cone including an angle of about 60, can beconstructed by drilling the skewed passages12 with a diameter of .132 inch on an ofiset of .31 inch from the central axis and at an. angle shown as 'A in Fig; 4of about 30. It is realized .that angle A, as shown in the drawing, is not a true angle relative to the centerline of passage 9, since the lines forming its sides do not'intersect oneanother, but is merely an 'angle'measuring the projection ofthe axis of skewed passage"12 upon central axis 13;; It forms a true angle relative tosurface. 1d, howevefland is used in manufacture. .Theseskev'vedpassages 12 are preferably drilled from the face of the nozzle as illustrated by the fragmental portion of a drill bit -18,

In the embodiment shown, there are .4 ameter skewed passages 12 equally spaced about the circumference of the nozzle face which are drilled so that angle A is 30. The central conduit 9 is drilled from the rear of the nozzle core with a diameter of .25 inch and then the fuel passages 14 are drilled at an angle of 30 with face 1d, with a .041 inch diameter bit, the drill bit entering through the opening formed by skewed passage 12 in the face 1d and piercing the opposite wall of skewed passage 12 to intersect with the wall of conduit 9 and the central axis 13. The above drilling angles result in an angle of entry of about 60". Thus a simple three-step drilling process, with an indexing operation on two of the steps, provides an extremely efiicient and eifective'arrangement of fuel and atomizing jets in a nozzle which is relatively free from the problerns caused by carbonization and deposition of fuel and fuel additives. The above procedure'results in a very good nozzle having a capacity of about 100 gallonsper hour with air and fuel supplypressures of 180 and 'l65 pounds per squareinchabsolute respectively.

in operation, the pressurized fuel entering from conduit 5 passes through the strainer 8, along the central conduit 9 and is subdivided to be ejected from the fuel jets 14. The atomizing fluid, air in this case although it could also be steam or any gas, enters through conduit 6, flows inside the cavity 1-1and through skewed passages 12. The mixing zone, where the viscous fuel is efficiently atomized due to the previous subdividing and the high angle of entry of the fuel into the atomizing stream, is approximately'at the face of the nozzle rather than inside the nozzle. The mixing proceeds'as the combined jets, their direction'being determined primarily by V the angle A of port 12, proceed to diverge outwardly from the nozzle face. The-nozzle faceis preferably flat to avoid the possibility of'any fuel forming on and dripping from the nozzle, as is'the case with many nozzles having conical tips. i I

The spray cone angle is primarily determined by the orientation of the atomizing jets issuing from passages 12, the fuel issuingfrom passages '14 having little effect onthe stream. Therefore, in order to modify the nozzle design to fit a combustion chamber requiring a wider angle of divergence of the spray cone, it is only necessary to modify the drilling angle of drill bit 18 to increase angle A to a greater value, for example 35. This will result in a spray cone of an included "angle of approximately 70.

The simplicity and ease of manufacture of the onepiece atomizing and spraying nozzle core will be apparent. Due to the ability to drill the mixing ports from the exterior face of the nozzle core, it is unnecessary to have the core made up of several elements having complex passageways and sealing surfaces such as exist in many prior art nozzles.

Another. advantage of the nozzle described is that it providesa high entry angle of the fuel into the atomizing stream, thus insuring efiicient atomization. Also, the use of skewed holes allows a Wide angle of divergence of the spray cone in a relatively small nozzle core; While the nozzle described is particularly eflicient for atomizing and spraying Bunker C fuel for combustion, it is also suitable for dispersing other liquids.

Modifications of the relative diameters, number, and

7 location of the ports will be apparent to those skilled in cations thereto which fall within the spirit and scope of h se sh ms What we claim as new and desire to secure by Letters Patent of the United States is:

1. A combination atomizing and spray tip of onepiece construction comprising a cylindrical body having a first transverse surface and a second transverse surface spaced axially from said first surface, the body defining a first series of circumferentially spaced passages extending therethrough from said first surface to said second surface, each of said first series passages being of circular cross-section and having an axis which is skewed with respect to the central axis of said cylindrical body, and a second series of circumferentially spaced passages radially inward from and equal in number to said first series passages extending from the second surface to intersect the first series passages, each of the second series passages having a circular cross-section and having an axis which is coplanar with and divergent from the central axis, whereby the axes of each pair of first series passages and second series passages intersect at a point lying substantially in the plane of the first surface to effect mixing adjacent the first surface of a first and a second fluid entering the first and second series passages respectively.

2. A liquid-atomizing spray nozzle core comprising a cylindrical body member terminating in a radially extending end flange, said flange having a first flat circular end surface and a second annular surface spaced axially from the first surface, said first and second surfaces being substantially normal to the central axis of the body, a central inlet conduit defined by the cylindrical body and disposed along the central axis of the body and terminating short of said first flange surface, said end flange defining coaxial first and second series of equal numbers of circumferentially spaced passages of circular cross-section, each passage of the first series extending from said first to said second surface of the end flange and having its axis skewed with respect to the axis of the body member so as to be non-coplanar therewith, each passage of the second series communicating with the central inlet conduit and diverging therefrom as the elements of a right circular cone with the outer end of the passage intersecting one of said first series passages, the axes of said intersecting pairs of passages meeting substantially in the plane of the flange end surface, whereby mixing of first and second fluids supplied to the respective first and second series of passages will be effected substantially in the plane of said first flange end surface.

3. A combination fuel atomizing and spray nozzle core for effecting the atomization of liquid fuel with an atomizing fluid and discharging the mixture in a frustoconical spray pattern, said core comprising a cylindrical body member terminating in a radially extending flange, said flange defining inner and outer surfaces normal to the central axis of said cylindrical body and having a first series of'circumferentially spaced atomizing fluid passages extending therethrough from one of said surfaces to the other, each of said atomizing fluid passages being of circular cross-section and having its axis of flow along a straight line which is skewed with respect to the cylin drical body so as to be non-coplanar with the central axis, an inner conduit defined by the cylindrical body and lying along the central axis to terminate short of the outer flange surface, a second series of circumferentially spaced fuel passages, each of said ,fuel passages intersecting said inlet conduit and having its axis of flow along a straight line coplanar with the central axis, the axis of each of said second series fuel passages intersecting with the plane of the outer flange surface within the periphery defined by the intersection of a first series passage with the outer surface.

References Cited in the file of this patent UNITED STATES PATENTS 1,075,742 Weintz Oct. 14, 191-3 1,230,982 Barber June 26, 1917 1,568,427 Strachan et al. Jan. 5, 1926 1,727,464 Debus Sept. 10, 1929 2,063,713 Voorheis Dec. 8, 1936 2,302,021 Freeman Nov. 17, 1942 2,595.759 Buckland et a1 May 6. 1952

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