US2613997A

US2613997A - Fuel atomizing nozzle

Info

Publication number: US2613997A
Application number: US58401A
Authority: US
Inventors: Thomas M Ball
Original assignee: Chrysler Corp
Current assignee: Old Carco LLC
Priority date: 1948-11-05
Filing date: 1948-11-05
Publication date: 1952-10-14
Anticipated expiration: 1969-10-14

Description

OGL 14, 1952 T. M. BALL 2,613,997

FUEL ATOMIZING NozzLE:

Filed Nov. 5, 1948 Patented ct. i4, i952 FUEL ATOMIZING NOZZLE lThomas M. Ball, Detroit, Mich., assigner to Chrysler Corporation, Highland Park, Mich., a

corporation of Delaware Application November 5, 1948, Serial No. 58,401

i Claims.

The present invention relates to atomizing 'nozzles such as used for supplying fuel to combustion chambers and more particularly to the socalled return flow or continuous bypass type nozzle.

A broad object of this invention is to produce an atomizing nozzle offering the cool operating behavior and other marked advantages inherent in return flow nozzles and yet being unhampered by the usual disadvantages attendant with the problem of confining the fuel, air-free, to its assigned passages.

Another object is to provide a nozzle of which the swirl chamber has a portion of its confined fuel withdrawn therefrom for bypassspurposes without any prospects of air being sucked into the bypass passages along with the fuel.

A further object is to provide a spray-type structure of simple construction and relative ease of manufacture.

Yet another object is to produce a nozzle built on return fiow principles providing positive and adjustable seals for the holder whereby various.

stages are effectively isolated from one .another and from the outside to insure against all possible leakage. Still another object is to provide at the relatively cooler operating portions of a nozzle, that is, where the danger from excessive heat deterioration is precluded, a deformable seal susceptive of exact and controlled adjustment such that commonly experienced leakage may be avoided.

Yet a further object isto provide in a nozzle effective heat dams by the fuel passages themselves for protection of the less rugged metallic portions. A Still a further object is to produce an improved spray nozzle comprising a few parts and being simple in operation, easy to assembly and disassemble, and capable of being manufactured at low cost, Additional objects and advantages are within the scope of this invention such as relates to the arrangement, operation and functioning of the related elements of the structure to various details in combination of parts, elements per se and to economies of manufacture and numerous other features as will be apparent from a consideration of the specification and drawings of a form of the invention which may be preferred .in which: l Fig. 1 is a longitudinal section of a fuel nozzle embodying the invention; f-

Fig. 2 is a perspective view of a kerfed. member for the spray tip in which the general angularity of the face passages has been rendered oblique; and

Fig. 3 shows a form of the invention employing a modified spray tip.

In particular regard to Fig. l of the drawing, the nozzle showncomprises in essentials an inner casing surrounded by, and in radial spacing, to an outer casing or sleeve. This outer casing terminates in a tip which may be received by the holder le. An inlet passage I2 and an outlet passage Id may be formed in the holder to establish fuel supply and bypass return conduits. The outlet passage i4 communicates with a return chamber I6 forming an open end for the holder and being restricted at its inside end by the face i8 `of an internal annular flange 22. Flange 22 may be disposed inwardly to define an aperture 24 which enters into a radially extended annular recess 26. In axial continuation of recess 26 there may be provided in the holder a threaded portion 28 for adjustable reception of the `head 30. By means of thisthreading the head may be'adjustably positioned against washer 32 which is interposed to provide a liquid-tight seal between the two members I0 and 30. This washer may be constructed of some material suitable to withstand relatively high temperatures and may be desirably formed from annealed copper. The head 30 may be hollow and consist axialwise of a threaded portion 33 which flares into an annular chamber 34. The walls of the'annular recess 34 merge inwardly to produce at their end an inner surface 36. The recess 34 thereby assumes more or less the form of a toroidal chamber. Supported within the head may beprovided a tip proper 4E! comprising two elements'42 and I4v arranged coaxially. The outer element 42 may be formed with an ejection orifice 46 and may be interfaced as at 48 vwith the complementary'e'lement 44. Member 44 on the other hand maybe provided with a companion rim flange 5I within which may be received element 42 in axial aligne` ment, and'provided also with slots ory kerfs 5.". cut into its interface 58.` The two cooperating pieces form in effect a member defining ac'entral swirl chamber 54 into which the passages 52 feed tangentially. For forcibly abutting -and supporting the swirl chamber member" andv constituting an essential part of the 'inner casing, there may be provided a sleevelv' '18 having a terminal member orhead-SZformed with passages as at E4..- The endiof-this Spassaged terminal may be faced off as'at itoprduce a floor for the swirl chamber" and maybe provided at its extreme periphery with an annular recess 68 which serves to space the faced off member from the rear of the spray tip proper. There thus results an annular chamber located radially on the fringes of the actual swirl chamber. The take-off passages 64 located around the annular recess 68 converge toward the rear of the nozzle and merge into a central conduit 12 which serves as bypass for the head. .An annular radial ange 14 has a threaded circumference by means of which the sleeve is positioned within the head described and by means of which fluid seals are maintained between the tip proper and the associated structure. Through the flange 14 there may be provided bores such as at 16 to provide for passage of fuel. The inner casing extends inwardly of the nozzle and may include a necked down portion 82 which serves as a toroidal shank. Shank 82 may be received in the aperture 24 of the holder and may extend on into the return chamber I6 thereof. This shank may thus serve to dene an annular recess adapted to receive a deformable grommet or ring 84 forming a seal between the inner and outer casings. This packing is preferably of a soft metal such as silver for example, but on the other hand may be of a plastic or rubber-like consistency. The primary concern in choice of its composition is no doubt that the seal withstands the temperature in the normal operating range of the nozzle and the less elevated temperatures will permit use of less heat resistant materials. Bore I6 may be observed from the figure to be tapped to form an adjustable gland recess means. Provided for reception in this recess means may be a gland or clamping means 86 in which is formed a hollow bore 92. By appropriate employment of the vclamping means the seal 84 may be adjusted so as to provide a non-leaking packing as between the casings and to this end the member 86 may be formed with means for receiving an adjusting tool as by slot 94 for varying the pressure on the seal. The tapped bore I6 continues through to the end of the holder and is adapted to be blanked off by a plug as at 96. This plug may have a lip 98 arranged to engage a washer such as shown at |02 to provide a seal as between the plug and the holder. This washer may be made of annealed copper or the like. The plug 96 may be formed with a, recess as at |04 for embracing an Allen wrench or other adjusting means to control the compression on washer I 02.

As to operation of the structure just described, conduit |2 supplies high pressure fuel which is fed into the high pressure stage of the nozzle.

Upon entering, the fuel will tend to fill up the annular chamber 26 and serve to provide a heat dam as between the direct line of heat transmitted through the tip of the nozzle as would ordinarily affect the non-metallic packing 84. The transit of the iiuid is such that it passes between the inner and outer casings through ports 'I6 provided in the ange 14 and into the toroidal chamber in part defined by recess 34. Passages 52 in the swirl member represented in the figure as being coplanar tend to swirl in the fuel from the tcroidal chamber into the swirl chamber 54 in a state of turbulent ow. From the swirl chamber 54 the fuel ow takes two paths, as hereinafter described, into which it is split up in varying proportions depending upon the particular nozzle output required. That is to say, the nozzle l is continuously bypassed and the amount of bypass bears an inverse proportional relationship to the amount of fuel n LA sprayed out of the nozzle. The resulting proportions of the foregoing relationship depend in turn on the respective back pressure and supply pressure being maintained on the nozzle, it being the general case, for example, that if the supply pressure is increased independently of change in the back pressure or that if the back pressure is decreased independently of change of the supply pressure, then the bypass rate of flow from the nozzle increases. It is found, however, that the nozzle tends to admit air through the ejection orifice 46 under the circumstance of certain conditions in the nozzle operating range Which sometimes prevail, for instance, when the proportion of bypassed fuel is relatively great in comparison to the fuel actually being ejected by the nozzle, and particularly so when the ambient atmosphere around the nozzle (that is, the atmosphere of the flame chamber in which the nozzle is located) is under a pressure which approaches or exceeds certain local pressures existing internally of the nozzle. The latter said local pressures depend in part on the back pressure of the nozzle. It is, of course, undesirable that air enter or be sucked into the nozzle and introduced into the bypass of the system for the reason that the air must later be purged as another operation from the system and cannot be allowed to remain and recirculate therein.

In the swirl chamber 54, a continuous portion of the fuel thus introduced is swirled outwardly through the ejection orifice 46 to produce a flame in the burning chamber. Owing to the centrifuge principles involved the fuel, being relatively denser than any vapors or gases which might exist in the swirl chamber due to cavitation or direct entry of the air through orifice 46, will tend to hug the outside of the swirl chamber. The portions of the swirl chamber otherwise than occupied by the fuel will be localized more or less in the center portion. Accordingly the whirling fluid will be entirely rid of any entrained air or vapors by the time it reaches the outer fringes of peripheral takeoff 68. The takeoff passages 64 then can transmit only the pure fuel into the bypass line, thereby precluding the above mentioned possibility of sucking air in such a bypass arrangement. The bypassed portion of the iiuid will then be passed down through conduit 'I2 and into the low pressure stage area. From the return chamber I6 this fuel will be conducted on away from the nozzle by conduit I4. With the grommet 84 adjustably positioned in the strategic position between the high pressure stage and the low pressure stage, fuel passing from one stage to the other needs must pass through the swirl chamber and through the passage l2 since between the two stages any possibility of leakage is eifectually circumvented. As regards leakage to the outside, the washers 32 and |02 are so positioned as to be adjustably sealable and are thereby not subject to leakage.

Preliminary to the discussion of Fig. 2 the fact should be pointed out that the tangential passages feeding the swirl chamber have for their prime object the function of spinning in the fuel and producing agitation vortices in the swirl chamber. It may be found, however, that the turbulence desirable may be more suitably produced if the flow passages are not strictly coplanar as represented in Figure 1 but rather cut, as in Figure 2, with the bottoms |53 of the kerfs |52 disposed along more of a conical region such that the mean longitudinal axis of each passage is non-coplanar as respects the balance.

In respect to Fig. 3, the embodiment shown may have a head 230 in which is carried the tip 240 comprising a unitary member. In one end of the tip 240 may be an axial ejection orifice 246 communicating with swirl chamber 254. Drilled through the walls of this swirl chamber may be provided small passages 252 adapted to swirl any fluid from the toroidal chamber 234. These passages 252 are represented as being coplanar although it may be found advantageous to dispose these passages so as to lie oblique to the axis of the nozzle. The next succeeding member, which carries the tip, may have a faced off floor portion 266, at the ends of which are recess means 26B. The takeoi recess may be served by passages 264 similar to passages 66 above described and merging into a central bypass conduit 212. The assemblage and operation features of this embodiment are essentially the same as outlined in the foregoing discussion. The structure as disclosed may be found to be particularly suitable for high temperature operation such as is encountered ingas turbine installations. The non-leaking system of closed circulation aifords the expedient of keeping the nozzle relatively cool and makes available the advantageous spray control afforded by the simple regulation of bacl; pressure on the return line. Contemplated Within its broader aspects, there may be ready application of the invention to oil burning furnaces and the like.

What is claimed is:

1. An atomizing nozzle comprising a hollowi headed outer casing having a centrally restricted body and an inner casing within the body of said outer casing received in said restriction, said outer casing having internal threads in the said hollow head thereof, said inner casing having a threaded flange received in said hollow head, and engaged by the internal threads of the same and held thereby in spaced relationship to the end of said hollow head, a spray tip held between and engaged by the inner casing and said end of the hollow head, said spray tip having an ejection orice formed therein at a location remote to said inner casing, an axially aligned cylindrical chamber behind said orifice and being constructed and arranged as to admit air through the ejection orice at one end thereof during a circumstance of operation in the operating range of the nozzle, said chamber being open-ended at the other end and said inner casing presenting a recessed transverse surface of a larger diameter than that of the cylindrical chamber and longitudinally spaced from said open-ended other end and forming a floor for the chamber extending circumferentially laterally of the open end of said chamber so as to form therewith a continuous cylindrical path of revolution; said spray tip further having whirl-producing passages formed therein so as tangentially to intersect said cylindrical chamber for whirling fuel thereinto and arranged in spaced relationship to the cylindrical path of revolution aforesaid to which at least a portion of the whirling fuel progresses, and means for selective takeoff and drainage from the said path of revolution, of fuel to the exclusion of air and comprising collecting passages in said floor at the periphery thereof and intersecting said path of revolution and extending convergingly and axially therefrom into said inner casing.

2. An atomizing nozzle comprising a hollowheaded outer causing having a centrally restrict'- ed body and an inner casing within the body .of said outer casing received in said restriction, said outer' casing having internal threads in the said hollow head thereof, said inner casing having a threaded flange received in said hollow head, and engaged by the internal threads of the same and held thereby in spaced relationship to the end of said hollow head, two axially aligned elements forming a spray tip held between and engaged by the inner casing and said end of the hollow head, said spray tip having an ejection orice formed therein at a location remote to said'inner casing, an axially aligned cylindrical chamber behind said orifice and being constructed and arranged as to admit air through the ejection orifice at one end thereof during a circumstance of operation in the operating range of the nozzle, said chamber being open-,ended at theY other end and said inner casing presenting a recessed transverse surface of va larger diameter than that `of the cylindrical chamber and longitudinally spaced from said open-ended other end and forming a floor for 4the chamber extending circumferentially laterally of the open end of said chamber `so as to form therewith a continuous cylindrical path of revolution; said spray tip further having whirl-producing passages formed therein between said two said elements thereof so as tangentially to intersect said cylindrical chamber for whirling fuel thereinto and arranged in spaced relationship to the cylindrical path of revolution aforesaid to which at least a .portion of the whirling fuel progresses, the longitudinal axes of said passages `being coplanar, and means for selective takeoff and drainage from the said path of revolution, of fuel to the exclusion of air and comprising collecting passages in said oor at the periphery thereof and intersecting said path of revolution and extending convergingly and axially therefrom into said inner casing.

3. An atomizing nozzle comprising a hollowheaded outer casing having a centrally restricted body and an inner casing within the body of said outer casing received in said restriction, said outer casing having internal threads in the said hollow head thereof, said inner'casing having a threaded flange received in said hollow head and engaged by the internal threads of the same and held thereby in spaced relationship to the end of said hollow head, a spray tip of one-piece construction held between and engaged by the inner casing and said end of the hollow head, said spray tip having an ejection orifice formed therein at a location remote to said inner casing, an axially aligned cylindrical chamber behind said orice and being constructed and arranged vas to admit air through the ejection orifice at one end thereof during a circumstance of operation in the operating range of the nozzle, said chamber being open-ended at the other end and said inner casing presenting a recessed transverse surface of a larger diameter than that of the cylindrical chamber and longitudinally spaced from said open-ended other end of said chamber forming a oor therefor extending circumferentially laterally of the open end of said chamber so as to form therewith a continuous cylindrical path of revolution; said spray tip further having whirl-producing passages formed therein so as tangentially to intersect said cylindrical chamber for whirling fuel thereinto and arranged in spaced relationship to the cylindrical path of revolution aforesaid to which at least a portion of the whirling fuel progresses, the longitudinal axes of said passages being coplanar, and means for selective takeoff and drainage from the said path of revolution, of fuel to the exclusion of air and comprising collecting passages in said oor at the periphery thereof and intersecting said path of revolution and extending convergingly and axially therefrom into said inner caslng.

4. An atomizing nozzle comprising a hollowheaded outer casing having a centrally restricted body and an inner casing within the body of said outer casing received in said yrestriction, said outer casing having internal threads in the said hollow head thereof, said inner casing having a threaded flange received in said hollow head and engaged by the internal threads of the same and held thereby in spaced relationship to the end of said hollow head, two axially aligned elements forming a spray tip held between and engaged by the inner casing and said end of the hollow head, said spray tip having an ejection orice formed therein at a 1ocation remote to said inner casing, an axially aligned cylindrical chamber behind said orifice and being constructed and arranged as to admit air through the ejection orifice at one end thereof during a circumstance of operation in the operating range of the nozzle, said chamber belng open-ended at the other end and said inner casing presenting a recessed transverse surface of a larger diameter` than that of the cylindrical chamber and longitudinally spaced from said open-ended other end of said chamber forming a floor therefor extending circumferentially laterally of the open end of said chamber so as to form therewith a continuous cylindrical path of revolution; said spray tip further having whirlproducing passages formed therein between two said elements thereof so as tangentially to intersect said cylindrical chamber for whirling fuel thereinto and arranged in spaced relationship to the cylindrical path of revolution aforesaid to which at least a portion of the whirling fuel progresses, the longitudinal axes of said passages being non-coplanar according to a generally conical configuration, and means for selective takeoff and drainage from the said path of revolution, of fuel to the exclusion of air and comprising collecting passages in said floor at the periphery thereof and intersecting said path of revolution and extending convergingly and axially therefrom into said inner casing.

THOMAS M. BALL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,037,645 Vroom et al Apr. 14, 1936 2,120,388 Bargeboer June 14, 1938 2,177,781 Haynes et al Oct. 31, 1939 2,239,068 Wood Apr. 22, 1941 2,373,707 Peabody Apr. 17, 1945 2,439,257 Lum Apr. 6, 1948