US3648457A - Combustion apparatus - Google Patents

Abstract

A combustion apparatus and fuel delivery means therefor having a spray nozzle projecting into a housing and adapted to direct fuel toward an annular array of vanes. The vanes are spaced radially outwardly of a housing outlet which is disposed in flow communication with the combustion chamber, and are adapted to receive pressurized air and direct it radially inwardly of the housing so as to generate a whirling mass of air within the housing and a vortical discharge from the outlet, whereby large fuel particles are centrifugally prevented from entering the combustion chamber until they have been sheared into small atomized droplets and small fuel droplets are entrained in the vortex and carried into the combustion chamber in a highly dispersed manner.

Description

United States Patent Bobo [451 Mar. 14, 1972 [54] COMBUSTION APPARATUS Primary Examiner-Douglas Hart [72] Inventor Melvin Bobo Cmcmnau Ohm Attorney-Derek P. Lawrence, Lee H. Sachs, Frank L. New [73] Assignee: General Electric Company hauser, Oscar B. Waddell, Joseph B. Forman and Thomas J. [221 Filed: Apr. 30, 1970 [2]] Appl. No.: 33,244 [57] ABSTRACT A combustion apparatus and fuel delivery means therefor hav- -----60/ 1/183 ing a spray nozzle projecting into a housing and adapted toCl t v v F231 10 direct fuel toward an annular array of vanes. The vanes are of Search R, paced radially outwardly of a housing outlet is 431/9 disposed in flow communication with the combustion chamber, and are adapted to receive pressurized air and direct [56] References Clted it radially inwardly of the housing so as to generate a whirling UNITED STATES PATENTS mass of air within the housing and a vortical discharge from the outlet, whereby large fuel particles are centrifugally 2,443,707 6/1948 Korsgren 0/ 97 prevented from entering the combustion chamber until they 2,452,779 11/1948 MCCOUUITI 1 83 have been sheared into small atomized droplets and small fuel 2,657,531 11/1953 Plefce droplets are entrained in the vortex and carried into the com- 2,999,359 9/196 Murray 60/ 39-74 bustion chamber in a highly dispersed manner. 3,134,229 5/1964 Johnson..... ...60/39.74 3,451,216 6/1969 Harding ..60/ 39.74 6 Claims, 4 Drawing Figures Z2 /2 M .20 ,Z

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PATENTEDHAR 14 I972 SHEET 2 [1F 2 INVENTOR. MELVIN B080 fiw FM Z COMBUSTION APPARATUS This invention relates to gas turbine engines and, more particularly, to combustion and fuel delivery apparatus for use in such engines.

The invention described and claimed in the United States patent application herein resulted from work done under United States Government Contract FASS-66-6. The United States Government has an irrevocable, nonexclusive license under said application to practice and have practiced the invention claimed herein, including the unlimited right to sublicense others to practice and have practiced the claimed invention for any purpose whatsoever.

Delivery of fuel into a continuous burning combustion apparatus, of the type commonly employed in gas turbine engines, in such a manner as to achieve complete and efficient combustion while minimizing the occurrence of fuel-rich pockets which, upon combustion, produce carbon or visible smoke has posed a continuing design problem.

Solutions to the foregoing are complicated in gas turbine engines by the wide range of fuel flow rates and combustion air temperatures and pressures encountered in the normal operating range and by the required or desirable light-off and lean extinction characteristics of the combustion apparatus.

While spray atomizing nozzles of the well-known type adapted to utilize fuel pressure to deliver a single or dual cone of atomized fuel into the combustion chamber of a gas turbine engine through a small discharge orifice tend to exhibit good light-off and lean extinction characteristics, such nozzles are inclined to produce local fuel-rich pockets at high fuel flow rates and hence visible smoke efflux. On the other hand, fuel atomizing and/or vaporizing devices which utilize the energy of pressurized air, such as the gas turbine engine compressor discharge air, and/or the heat from the combustion process to deliver a fuel/air mixture to the combustion chamber may, in some installations, exhibit poor ignition or lean extinction characteristics due either to an overly lean or dispersed fuel/air mixture at low fuel flow rates or a lack of sufficient energy in the combustion process or a lack of sufficient energy in the compressor discharge air to achieve the required fuel atomization. Additionally, such atomizing and/or vaporizing devices, of the type heretofore employed, generally introduce the fuel into the air stream at a point remote from or substantially upstream of the primary zone of the combustion chamber, which may under certain operating conditions encourage propagation of the flame upstream of the combustion chamber, flashback or an otherwise unstable flame front.

The primary object of this invention is, therefore, to provide an apparatus for delivery of fuel into the combustion chamber of a gas turbine engine in a highly dispersed manner so as to substantially eliminate or mitigate the occurrence of visible smoke in the products of combustion.

A further object of this invention is to provide a low smoke, continuous burning combustion apparatus for a gas turbine engine which exhibits stable burning and possesses good lightoff and lean extinction characteristics over a wide range of engine operating conditions.

Further objects and advantages of this invention will become apparent upon reading the following description of the preferred embodiments.

Briefly, the above and other objects of this invention are achieved by providing a housing having a downstream end wall formed with an outlet communicating with the combustion chamber. The housing includes an annular array of swirl vanes for directing pressurized air inwardly of the housing with a substantial tangential component so as to generate a whirling mass of air within the housing and a vertical or cyclonic discharge from the outlet. Fuel injection means are provided for spraying fuel toward the vanes. The vanes are spaced radially outwardly of the outlet so that the large or heavy fuel particles are centrifugally retained within the housing until they have been sheared into small atomized droplets, whereupon such droplets are entrained in the vortex and carried into the combustion chamber.

By a further aspect of this invention, the fuel injection means is additionally adapted to provide a pilot conical spray of atomized fuel directly into the combustion chamber so as to enhance light-off characteristics during those portions of the engine operating regime whereineith er fuel flow rates are low or the compressor discharge air lacks sufficient energy to satisfactorily atomize the fuel. The swirl vanes are preferably disposed in overlapping relationship so as to foreclose fuel discharge through the vanes.

While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter of this invention, it is believed that the invention will be better understood upon reading the following description of the preferred embodiments in conjunction with the accompanying drawings wherein:

FIG. 1 is a fragmentary axial cross-sectional view of gas turbine engine employing the fuel delivery and combustion apparatus of this invention;

FIG. 2 is a view like FIG. 1 showing a further aspect of this invention;

FIG. 3 is an enlarged partial cross-sectional view of the discharge end of the fuel nozzle of FIG. 2; and

FIG. 4 is a cross-sectional view taken along lines 4-4 of- FIG. 2.

Like reference numerals will be used in referring to like parts throughout the following description of the drawings.

With reference first to FIG. 1, a continuous burning combustion apparatus for a gas turbine engine has been shown generally at 10 disposed within suitable engine casing structure 11 and as comprising ahollow body 12 defining acombustion chamber 14 therein. Thehollow body 12 includes a domed upstream end 16 having an inlet opening 18 therein for receiving a fuel/air mixture. As will be understood by those skilled in the art, thecombustion chamber 14 may be of the annular type, the cannular type, or the can type, with theapparatus 10 having a plurality of circumferentially spacedopenings 18.

Asnout assembly 20 is suitably secured to the upstream end of thehollow body 12 and is adapted to receive a pressurized flow of air from a suitable source, such as a compressor (not shown).

Afuel delivery apparatus 22 is provided at the upstream en ofhollow body 12 and comprises ahousing 24 having axially spaced upstream anddownstream walls 26 and 28, respectively, with thedownstream wall 28 formed with anoutlet 30 in flow communication with thechamber 14 throughinlet 18. An annular array ofvanes 32 is provided to direct the pressurized air from within thesnout assembly 20 inwardly of the housing so as to generate a whirling mass of air within thehousing 24 and a vortical or cyclonic discharge throughoutlet 30, as shown generally at 34.

For reasons which will hereinafter become apparent, the array ofvanes 32 is spaced radially outwardly of theoutlet 30 so as to define anannular chamber 36 between the radialinner edge 37 of each vane and theoutlet 30.

Means for injecting fuel internally of thehousing 24 and toward thevanes 32 have been shown at 38 in FIG. 1 as comprising a fuel spray nozzle having adischarge end 40 of the wellknown type adapted to utilize fuel pressure to generate a conical spray of atomizedfuel 42. The fuel nozzle discharge end 40 projects throughupstream wall 26 ofhousing 24 and is preferably disposed with its discharge axis coaxial to thehousing outlet 30.

By a further aspect of this invention and with reference now to FIGS. 2 and 3, thedischarge end 40 of fuel injection means 38 is adapted to provide a fuel spark 4-2 as a plurality of radial spokes or streams throughopenings 44 and a fuel flow passage 46, and, additionally, to provide a pilot spray cone of atomized fuel 48 directly intocombustion chamber 14 throughorifice 50 andpassage 52. In this manner, it has been found that the ignition and lean extinction characteristics of thecombustion apparatus 10 are greatly enhanced. This is particularly true in aircraft applications during altitude relight conditions when the compressor discharge air of a gas turbine engine may not have sufficient energy to finely atomize thefuel 42.

Thehousing 24 may include fluid directing means outwardly of thevanes 32 for efficient and streamlined delivery of the pressurized air thereto so as to enhance the strength of the vortical flow within the housing. For example, and with reference to FIGS. 2 and 4, the housing may include anouter wall 52, which extends between upstream anddownstream walls 26, 28, outwardly of thevanes 32. In the embodiment of FIG. 4, theouter wall 52 is involute or spiral in shape and forms atangential inlet 54 for delivery of pressurized air to thehousing 24. In addition, means 56, which extend upstream of thehousing 24 and communicate withinlet 54, may be provided for streamline delivery of the pressurized air to theapparatus 22. It will be appreciated, however,'that such fluid directing means may be widely varies.

In operation, air having a higher total pressure than that withinchamber 14 is directed radially inwardly of thehousing 24 with a substantial tangential velocity component by the array ofvanes 32 so as to establish a whirling mass of air within theannulus 36 and a vortical orcyclonic discharge 34 to thecombustion chamber 14 throughoutlet 30. Fuel is injected into theannulus 36 as a conical spray (FIG. 1), as a plurality of radial streams (FIG. 2), or otherwise bymeans 38. Upon discharge into thehousing 24, a portion of the large fuel particles may be sheared into small atomized fuel droplets by the high velocity vortical airflow, while the remaining large fuel particles are centrifugally impinged against thevanes 32 by the vortical airflow within thehousing 24. The fuel is then sheared off the radialinner edge 37 of each wetted vane as a finely atomizedspray 58 by the airflow across the vane, as best shown in FIG. 4. In this connection and as shown in FIG. 4, thevanes 32 are preferably disposed in overlapped relationship or with the leading edge 60 of eachvane 32 circumferentially overlapping thetrailing edge 37 of its immediately preceding vane so as to prevent the fuel from being sprayed or centrifuged through the vanes.

By spacing thevanes 32 radially outwardly of theoutlet 30, large or heavy fuel particles, which if introduced intocombustion chamber 14 would result in local overrich burning and hence smoke, are centrifugally retained behinddownstream wall 28 until they are atomized by one of the mechanisms described above into droplets of sufficiently small size that the centrifugal forces are overcome by the dragforces; whereupon such small particles are entrained in the swirling air and carried intochamber 14 with thevortex 34. In this manner, the present invention has been found highly effective in controlling the size of the fuel droplets entering thecombustor 14.

In gas turbine engine applications having widely varying fuel flow rates, the fuel injection means 38 may be conveniently adapted to deliver a small amount of fuel in the form of a conical atomized spray 48 directly into thecombustor 14 so as to enhance the ignition an lean extinction characteristics of the engine.

Since the fuel is introduced to the apparatus of this invention in close proximity to thecombustor 14, problems involving flashback or erratic propagation of the flame upstream of the combustor are eliminated.

I From the foregoing, it will be appreciated that the present invention provides novel and highly effective means for delivery of an air/fuel mixture, which is characterized by highly dispersed small fuel particles, to a combustion chamber.

While several embodiments of the present invention have been depicted and described, it will be understood by those skilled in the art that numerous changes and modifications may be made thereto without departing from the inventions fundamental theme.

What is claimed is:

1. A fuel delivery apparatus for a gas turbine engine, including, in combination, a housing formed with an outlet and including a plurality of fluid directing vanes disposed in a radially spaced annular array about said outlet said vanes adapted to drrect pressurized arr radrally inwardly thereof and generate a vortical flow of air internally of said housing and a vortical efflux from said outlet, and fuel injection means disposed in said housing adapted to deliver a first and second spray of fuel, said first spray of fuel being directed generally radially outwardly toward said vanes, whereby highly dispersed fuel droplets of controlled small size are discharged with said vortical efflux, and said second spray being directed through said outlet.

2. The fuel delivery apparatus of claim 1 further characterized in that said housing includes an upstream wall and a downstream wall, said vanes extending generally axially between said walls and disposed in overlapping relationship so as to prevent escape of said fuel through said vanes.

3. A continuous burning combustion apparatus including, in combination, a hollow body defining a combustion chamber therein and fonned with an inlet, a housing formed with an outlet in fluid flow communication with said inlet and including a plurality of generally axially extending fluid directing vanes disposed in an annular array outwardly of and about said outlet, fuel injection means projecting through an upstream wall of said housing for spraying fuel radially outwardly of said outlet toward said vanes, said vanes adapted to receive a flow of pressurized air and direct said air radially inwardly of said housing so as to generate a vortical flow of air internally of said housing and a vortical discharge to said combustion chamber through said housing outlet, whereby the fuel droplets within said spray are sheared into minute particles and carried with said vortical discharge to said combustion chamber in a highly dispersed manner.

4. The combustion apparatus of claim 3 further characterized in that said fuel injection means is further adapted to deliver an atomized spray of fuel directly into said combustion chamber.

5. The combustion apparatus ofclaim 4 further characterized in that the leading edge of each vane is disposed in circumferentially overlapped relationship to the trailing edge of the preceding vane.

6. A fuel delivery apparatus for a gas turbine engine, including, in combination, a housing formed with an outlet and including a plurality of fluid directing vanes disposed in a radially spaced annular array about said outlet, said vanes adapted to direct pressurized air radially inwardly thereof and generate a vortical flow of air internally of said housing and a vortical efflux from said outlet, and fuel injection means disposed in said housing for directing fuel radially outwardly toward said vanes, said fuel injection means, in cooperation with said vortical flow of air internally of said housing, being adapted to deposit at least a portion of said fuel on said vanes, whereby said fuel is sheared off a radial inner edge of each said wetted vane by the pressurized air flow over said vane as a spray of fuel droplets of sufficiently small size to be entrained in the vortical flow and discharged from said outlet with said vortical efflux.

Claims (6)

1. A fuel delivery apparatus for a gas turbine engine, including, in combination, a housing formed with an outlet and including a plurality of fluid directing vanes disposed in a radially spaced annular array about said outlet, said vanes adapted to direct pressurized air radially inwardly thereof and generate a vortical flow of air internally of said housing and a vortical efflux from said outlet, and fuel injection means disposed in said housing adapted to deliver a first and second spray of fuel, said first spray of fuel being directed generally radially outwardly toward said vanes, whereby highly dispersed fuel droplets of controlled small size are discharged with said vortical efflux, and said second spray being directed through said outlet.

2. The fuel delivery apparatus of claim 1 further characterized in that said housing includes an upstream wall and a downstream wall, said vanes extending generally axially between said walls and disposed in overlapping relationship so as to prevent escape of said fuel through said vanes.

3. A continuous burning combustion apparatus including, in combination, a hollow body defining a combustion chamber therein and formed with an inlet, a housing formed with an outlet in fluid flow communication with said inlet and including a plurality of generally axially extending fluid directing vanes disposed in an annular array outwardly of and about said outlet, fuel injection means projecting through an upstream wall of said housing for spraying fuel radially outwardly of said outlet toward said vanes, said vanes adapted to receive a flow of pressurized air and direct said air radially inwardly of said housing so as to generate a vortical flow of air internally of said housing and a vortical discharge to said combustion chamber through said housing outlet, whereby the fuel droplets within said spray are sheared into minute particles and carried with said vortical discharge to said combustion chamber in a highly dispersed manner.

4. The combustion apparatus of claim 3 further characterized in that said fuel injection means is further adapted to deliver an atomized spray of fuel directly into said combustion chamber.

5. The combustion apparatus of claim 4 further characterized in that the leading edge of each vane is disposed in circumferentially overlapped relationship to the trailing edge of the preceding vane.

6. A fuel deliVery apparatus for a gas turbine engine, including, in combination, a housing formed with an outlet and including a plurality of fluid directing vanes disposed in a radially spaced annular array about said outlet, said vanes adapted to direct pressurized air radially inwardly thereof and generate a vortical flow of air internally of said housing and a vortical efflux from said outlet, and fuel injection means disposed in said housing for directing fuel radially outwardly toward said vanes, said fuel injection means, in cooperation with said vortical flow of air internally of said housing, being adapted to deposit at least a portion of said fuel on said vanes, whereby said fuel is sheared off a radial inner edge of each said wetted vane by the pressurized air flow over said vane as a spray of fuel droplets of sufficiently small size to be entrained in the vortical flow and discharged from said outlet with said vortical efflux.

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