US2561939A - Dual spray nozzle for fuel burners - Google Patents

Description

July 24, 1951 R. G. MESCHINO DUAL SPRAY NOZZLE FOR FUEL BURNERS 2 Sheets-Sheet 2 Filed Dec. 30, 1948 (7111x1170? KW ,yrn

Rona/ G. Msczi-na Patented July 24, 1951 DUAL SPRAY NOZZLE FOR FUEL BURNERS Ronald Guerin Meschino, Toronto, Ontario; Canada, assignor to A. V. Roe Canada Limited, Malton, Ontario, Canada, a corporation Application December 30, 1948, Serial N 0. 68,291

I 9 Claims.

This invention relates to improvements in fuel burners and in particular to burners for the combustion chambers of gas turbine engines.

'In a gas turbine the fuel is injected into an air stream which has a high speed of flow and in order to obtain efficient combustion it is important that the fuel'should be thoroughly atomized and distributed as evenly as possible across the air stream. It is also important that good atomization and distribution should be obtained at all speeds throughout the range of operation of the turbine and at all rates of fuel flow.

Atbmization is commonly achieved by arranging the various ducts and chambers inside the burner so that the fuel in the burner is caused to rotate at a very high speed before emerging from the nozzle of the burner into the air stream. This rotation results in the fuel being sprayed from the'nozzle in a cone of fine particles, but variations in fuel pressure and rate of flow directly affect this atomization and at low pressures the swirling of the fuel is reduced to such an extent that atomization is seriously impaired. Various devices have been adopted to overcome this difliculty and of these the so-called spill-type burner is perhaps the most effective. In the spillty'pe burner the supply pressure is preferably kept constant, thus ensuring constant rate of swirl;

and-fuel in excessof requirements at thenozzle allowed to return to the tank through a controlled outlet line. Although this type of burner overcomes some of the chief problems of atomization, a single burner is liable'to cause too greata concentration of fuel in limited areas'of the 'air' stream at high rates of flow, resulting in inefii lem; combustion and waste of fuel. To meet this di'flicultya number of burners can belemployed';

but unless these are arranged'co-axially in the combustion chamber their cones of particles over lap; causing an uneven patternof fuel distribu'-' tion. In any case, the use of a multiplicityiof burners of the usual type is liable to be cumbersome. Furthermore, in all known forms of burn j ers utilizing a swirl of fluid inside the burner, the

swirling fluid and the air core which is created by the swirl must impinge at the inner end on the rear wall of the swirl chamber, which may be either'a' fixed wall or a wall of fluid in the spill passage. Consequently an undesirable drag effect is caused, and the air-core is likely to become unstable; causing corresponding instability of the spray.

e'r'in which two nozzles arearranged. co-axially' sucha way as to eliminate therinstabilityof An object of thisinvention isto provide a burn? flow which is inherent in all types of burners hav ing one or more independent swirl chambers.

A further object of this invention is toob'- tain improved atomization at lower inlet pressures, for any given rate of flow, by the use of two nozzles supplied from a common feed and in the case of the spill-type burner controlled through a common outlet line. Y

All of the foregoing and still further objects and advantages of the invention will become apparent from a study of the following specifica-' tion, taken in conjunction with the accompanying drawings, wherein like characters of-reference indicate corresponding parts throughoutthe several views and wherein: Fig. 1 is a side view of a spill form of burner constructed in accordance with this invention;

- Fig. 2 is an end view of the said burner;

Fig. 3 is a cross sectional view on the line- 33 ofFig.2;' Fig. 4 is a cross sectional view on the line 4-4 of Fig. l; 1

Fig. 5 is a cross sectional view on the line 5-5' ofFig.1; Fig. 6 is a longitudinal vertical cross sectional view of another form of burner, namely,- a burner of-the duplex type, constructed in accordance with this invention; i Fig. 7 is a cross sectional view on the line 1'| of Fig. 6; and i v Fig. 8 is a cross sectional view on the line 8-8 ofFig.6. I The spill burner illustrated in Figs. 1-5 comprises a body, indicated generally by reference numeral l0, thesaid body being cylindrical inshape and being supported in the combustion chamber of a gas turbine by inlet and outlet pipes II and I2 respectively. At opposite ends of the body are nozzle orifices l3 and I4 and the burner. is so placed in the combustion chamber that its. axis lies substantially parallel to the flow of air through the chamber. as indicated by the arrow. A, the nozzle orifice I3 facing downstream. of; the air flow and the, nozzle orifice l4 facing upstream. The body Ill includes a cylindrical barrel member l5 having a thick-walled portion IS in which an outlet orifice I! is provided; registering with the orifice I1. and secured to the thick-walled por. tion I 6 of the barrel member I5 is a sleeve it which receives an outlet pipe l2. Seven longitudinally disposed passages l9 are provided. in, the barrel member, these being symmetrically arranged around its axis. The thick-walled 'por--'. tion I6 of the barrel member is formed with an annular recess 20, and annular shoulders 21 and 2! which indirectly engage (being in practice spaced therefrom by packing glands) with the inner ends of central tubes 22 and 22 extending downstream and upstream respectively. The barrel member has at the upstream end an annular stepped portion 23 and an externally threaded extension 2d,. and has at the opposite end an outer annular shoulder 25 which engages with a. second barrel member 26 in which an in-- let orifice 2? is provided; registering with the orifice 21 and secured to the barrel member 26' is a sleeve 28 which receives an inlet pipe Ii. The second barrel member 26 has. at the downstream end an annular stepped portion 26 and an: externally threaded extension 26?. Closely fitting,

over the outer ends of the central tubes 22 and 22 respectively are the end blocks 30. and 31")" in which are provided the nozzle orifices l3 and UL co-axially communicating with tapered swirl chambers ti and. 3!. The swirl chambers are connected to annular recesses 32 and 32 by ports 33. and 33' respectively, the. ports entering the swirl. chambers tangentially as shown in Fig. 4. The end. blocks 30, and 3d are held in place-by internally threaded caps 34 and 34 which are. screwed on the ends of the barrel members 26 and. 1:5 respectively.

It will be seen that the arrangement of parts of. the body at the downstream end defines an annular chamber 35 having a relatively narrow annular recess 32; and at the upstream end defines an. annular chamber 35 having a. relatively narrow annular recess 32-. The two chambers 35 and 315' are interconnected by the longitudinal passages l9, and. chamber 35 is connected to the swirl chamber lit by the tangential ports 33 whereas; chamber 35' is connected to the swirl chamber 3| by the tangential ports 33". The Swirl chambers 31. and 3t areconnected: through the open passage constituted by the bores. 36 and; 3.6- of. the. central-tubes 22; and 22:, respectively, and by the central cylindrical chamber 31, which, is. defined by the annular recess the bores. 36; and. 36 are chamfered'. atifie and 36? respectively. The diameter of-the bores 36; and 36 is less than the diameter of ;the:swirl-, chambers 3L and 3t but materially greater than the diameter of either of the nozzle orifices-113 and 14. The. central! chamber! 31.- communicates w.ith= the outlet pipe [2.

-In the operation of: the spill burner, fuel under high pressure enters. the burner through; theii-nlet pipe H and fillsrthe: downstream annular chamber 3.5, passing through the:longitudinalpassages [.9 to fill the corresponding upstream. chamber Considering-first the operation of the downstream end of theburner, it willlbezapparent thatfuel from the. chamber 35% flows: through the ports. 33 into the swirl" chamber-.31; Since the ports. 33 enter the swirl chamber'3l. tangentially like torque-inducing directions, the incoming flow of fuel is-g-i-vena rotary motion, and under the high pressure applied the speed of rotation is very great. The fuel emerging from the nozzle orifice l 3-isin the form of a conical spray of finely di-- vlded particles 38. Fuel in excess ofrequirements is spilled off through the bore 36 to the central chamber 3!- whence it may be allowed to escape through theoutlet pipe I2. By controlling the outletfl'ow by a suitable valve it is possible to control the depth or thickness of the rotating layer of fuel in the swirl chamber 3| and thus oft-he burner.

4 orifice l3. The inlet pressure is maintained at an approximately constant value throughout the range of fiow required.

In the same manner, fuel is introduced into the upstream swirl chamber 3 l through the ports 33 and emerges from the upstream nozzle orifice Hi in a conical spray 38, excess fuel being spilled off through the bore 36. to the outlet pipe l2. Thus the two swirl chamber-nozzle systems are 1 fed by a common inlet and spill to a common outlet, which provides for a common control of their rate of spill. It will be noted that the ports 33 and. 3-3 are arranged in relation to their respective-swirl chambers 3i and 3| so that the swirl win each is inthe same direction, that is, anticlockwise when viewed from a point downstream The most important consequence of this arrangement is that the two systems have a common air core 39. In all burners employing the: swirl principle, an air core is formedaround theaxis. of thev rapidly. spinning, fi-uid and the: stability of the flow from the nozzle. depends; on the stability of. thisv coreu If. the inner. end of this core, that is the end remote from the nozzle impinges upon a wall; of. the swirl .chamber or upon: a. wall of fluid. in the. spill passage, it isl-ikely to be unstable at. varying rates of fiow; stability therefore can only be achievedif. the air core is open and unobstructed at both ends, and this result is obtained by the. invention. as herein described. 1

By the employment. of acommon outlet-system and a common inlet pressure, andswirl chambers of equaldiameter, the-depth-oi .iuel in the down--.

streamswir-l chamber 3|. isequal tothe depth oi fuel in the. upstream swirl. chamber 3| Thusthe: fuel emerging from. the. nozzle orifices Hand. II. can be apportioned-by the choice of the diameters of these orifices, in a manner appropriateto. the

fuel distribution required tor efiici'ent two stage combustion in theair stream.

Another embodiment of the. invention, in which the invention is. applied. to. aburner of the duplex..-

- type,, is shown in Figs. 6,. 7 and- 8. In the. nor- 42. and .43respectivel'y. At opposite end's ofjth'e body 4 Larethe-nozzle orificesiATifand 4'51. directed downstream andupstream; respectively, which are connected; by a singlelongitudinall centralfchamber. 46,. which provides. at opposite. ends. inter connected-terminal; swirl chambers. 41 and '4'T.;;'

it willfbe. noted that the swirl chambers 'arei'n.

practice provided. in end. blocks 48 and"49. barrel member 50,. having annular channelled portions 51",. 52 andi 5'3 and threaded ends 54? and, 51'', is secured around theendi blocks. fli an'vzl'v 49. by threaded end caps 56- andj56. I

The end' blocks 48"and43'are peripherally chan' nelled. to define, cooperationfwi'th the pegripheral channels 5|. and 53' in ftlie'barrel memf ber, annular chambers 51 'andf'5'8; 'at'the down: stream andlupstream ends'respectivel'yf The said annular chambers are connected by'lbngitudin'ali passages 59 which are symmetrically arranged around'the axis'of the burner: The primary fuel inlet" pipe" 4'2"comnmnicates directly. with;

the quantity of fuel emerging from the nozzle the annular'chamber 51" througlr'the inlet oriflce atencse nected to. the .central chamber 145iv bylports 61, and 62- respectively; which .enter' the; chamber 46 tangentially?new 'The'end'block 48 is; also peripherally chan-L nelled' at 148% todefine, in cooperationwith the,

inner faceof .the'end block 49- and the periphera-l g ly-channelled portion .52 in thebarrel member 50,, arelatively small secondary annular; chamber 63,. with which thesecondary inlet .pipe 43 ;directly communicates through the secondary inlet orifice, 64. j.The secondaryiannularchamber 63 is connectedsto the central-phamber 46, byvsecondary. portsGEi which, likeeportsfil and. 62, enter the ch'amber:.=46 .tangentially.-;-. 1 E

The operationof Atheduple burner ,is similar to that of, the spill burner,- except 'that ,the control of ,the fluid flow is effected by changes in; pressure in the-:secondary,inletpipe- 43 whichchanges the speed offlow through thesecondary, ports'65 and thereby directly aifects the velocity of swirl in the chamber t6.v The primary ,inlet, pressureis preferably keptsubstantially constant; As inthe spillburner, an air core common to both ends of the burner iscreatedand a; corre-p sponding stability of flow is achieved.

It is thought that the construction and use of the invention will be apparent-from the above description of the various parts and their purpose. It is to be understood thatthe forms of this invention, herewith shown anddescribed are to be taken as preferred examples "of the same, and that=various changes in. the shape, size and arrangement of the parts may be resorted to, without departing from the. spirit of the invention: and-the scope of the subjoined claims.

'Wha't I claim as my invention is:

lr A burner for liquid fuels comprisin a body having nozzle orifices atopposite ends, apassageway' withinthe body connecting the nozzle orififices, interconnected annular chambers e'ncircling the passageway, fuel ports leading from the annular chambersand, entering the passageway non-radially to'cause a swirling action of the fuel in the passageway, meansjfor conducting fuel from asouroe of-supplyunder pressure to the annular chambers, and a flow-regulating conduit communicating with the passageway, the passageway being adapted to provide between the nozzle orifices a continuous annular body of swirling fuel having an air-core extending through both nozzle orifices in the body.

2. A burner for liquid fuels comprising, a body, tapered swirl chambers within the body, the swirl chambers terminating in nozzle orifices situated tat opposite ends of the body, interconnected annular chambers disposed coaxially in the body, fuel ports leading from the annular chambers and entering the swirl chambers nonradially to cause a swirling action of the fuel in the swirl chambers, an inlet conduit for conducting fuel under pressure to the annular chambers, an open passageway connecting the swirl chambers and adapted to provide between the swirl chambers a continuous annular body of swirling fuel having an air-core extending through the nozzle orifices in the swirl chambers, and a flow-regulating conduit communicating with the passageway.

3. A burner for liquid fuels comprising, a body having nozzle orifices at opposite ends, tapered swirl chambers within the body having communication with the nozzle orifices, interconnected annular chambers disposed co-axially in the body, fuel ports leading from the annular chamv chambers and entering the end portions of the hers-and entering the swirl chambers, non-radial ly to cause a swirling action of the-fuelv in the, swirl chambers, an inlet conduit for conducting- 5 fuel under pressure to the annular chambers, an, open passagewayconnecting the swirl chambers;

and adapted to provide between the swirlchamaction of the fuel in the swirl chambers, an inlet conduit for conducting fuelunder pressure to the annular chambers, a central chamber in the body passageways connecting each ofv the swirl chant;

bers to the central chamberand adapted to provide between the swirl chambers a continuous annular body of swirling fuel having an air-pore;

extending through the nozzle orifices in the body,

and a flow-regulating outlet conduit communi eating with the central chamber. I

5. A burner for liquid fuels comprising, abody having nozzle orifices at opposite" ends, tapered, swirl chambers within the body having commu-, nication with the nozzle orifices, interconnected annular chambers disposed co-axially in the body, fuel ports leading from the annular chambers and entering the swirl chambers non-radiallyto cause a swirling action of the fuel in the swirl chambers, a primary inlet conduit for conduct-. ing fuel under pressure to the annular ch'am bers, a, passageway connecting the swirl cham= bers and adapted to provide between theswirl chambers a continuous annular body. of swirling,

fuel having an air-core extending through. the. nozzle orifices in the body, and a. flow-regulating.

secondary inlet conduit communicating with the,

6. A burner for liquid fuels comprising,-abody v having nozzle orifices at opposite ends a passageway within the body connecting the nozzle orifices and having convergingly tapered end portions constituting swirl chambers, interconnected annular end chambers disposed around and spaced from the end portions of the passageway, primary fuel ports leading from the annular end passageway non-radially whereby a continuous annular body of swirling fuel having an air-core extending through the orifices in the body is provided, a primary inlet conduit for conducting fuel under pressure to the annular end chambers, an annular control chamber disposed around the passageway between the annular end chambers, secondary fuel ports leading from the annular control chamber and entering the passageway non-radially, the said secondary fuel ports being adapted to increase the swirling motion of the fuel in the passageway, and a flow-regulating secondary fuel inlet for conducting fuel under pressure to the annular control chamber.

'7. A burner for liquid fuels comprising, a body containing an elongated passageway of circular cross-section for containing a rotating body of fuel and having axially directed discharge orifices at opposite ends, the body having two groups of fuel inlet ports leading into the passageway for delivering rotation-inducing jets of fuel at high velocity, each group of ports leading into one of theopposite end portions oi the passageway each port entering the passageway non-axially anal non-radially and allthe ports in botlrg roups" entering the passageway in the same rotary" sense, each groupof constituting means whereby the jets discharged therefrom: Wiilcause rapid 'vortical motion in the fuel corresponding end ofthe passageway around; core and the two groups of ports co-operating: to cause theair core produced by each group or parts to merge with the other air core into" a centinuousair coresurrounded by a continuous annular'bo'dy of swirling fuel and extending to full length of the passageway through both dischargeorifices, and means for conducting fuel under High pressure from a source of supply to thefuelinletp'orts.

8 A burner for liquid fuels eomprising, a body containing an elongated passageway of a circular cross-section for containing a rotating body of file-land having axially directed discharge ori-- fi'ces at opposite ends, an annular chamber in the body and encircling the passageway, the bod-y having two groups'of fuel inlet portsleadihginto the passageway for delivering rotation-inducing jets of fuel at high velocity, each group of ports leading into one of the opposite end portionsof the-passageway, each port entering the passageway non-axially and non-radially and all the ports in both groups entering the passagewayinthe same rotary sense; each group of ports constituting means whereby the jets discharged therefrom willcause rapid vertical motion in the fuel in the corresponding" end of the passageway around an air core and the two groups of ports co operating to cause the air core produced by each group-of ports tomerge with the other air core into a continuous air core surrounded by a'continuous annular body of swirling fuel andextending the full length of the passageway through both discharge orifices, means for conconducting fuel under high pressure from a source of supply to the annular chamber, and a flow-- regulating conduit communicating with the passage'way.

9. A burner for liquid fuels" comprising, a'body 8 containing? an elongaten passageway of circula cross s'ecticn for containing a rotatir igwbcdyrofi fuel the oppositeends of the passageway pro: viding swirl chambers terminatinggin axially die recte'd nozzle orifices situated at opposite ends of the body; theabody l'lavmgftwo groups oriuelr. inlet ports-- leading. i into. the passageway; for de liveringf rotationsinducingijets of fuel at highve locity; eachwgroup ofports leading into- 'one ofi the switl chambers; each port entering the passsageway non-axially ariation-radially and alt the ports in both groups entering the passageway thesame rotarysense; each group of portscon stituting' means whereby the. jets discharged therefrom will cause rapid vertical motioninntha fuel iri the corresponding swirl chamber around an air eore and the two groups of ports: co -wer ating to cause the air core produced. by; each; group of portstamerge with: the other aircore'g into a continuous air-Scoresurrounded bya com: tmuousannular body? ofswirlingifuel and extend mg then-11 1 length of the passageway thl'dlighiboth discharge orifices, and means for conduct e ing fuel under highpressure from a; source at supply to the fuel inlet ports RONALD GUERIN MESCHINO;

I REFERENCES CITED The following references" are of record in'thq

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