US2498728A - Combustion apparatus - Google Patents

Description

Feb. 28, 1950 s. WAY

coMBusTIoN APPARATUS Filed May '7, 1948 2 Sheets-Sheet 1 ,6% ATTORNEY l y 1 y l A A d l v r l l I r l l EA I Feb. 28, 1950 s. wAY

couBUs'rIoN APPARATUS 2 Sheets-Sheet 2 Filed May 7. 1948 Patented Feb. 28, 1950 COMBUSTION APPARATUS Stewart Way, Pittsburgh, Pa., assignor to Westlnghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application May 7, 1948, Serial No. 25,629

6Claims.

This invention relates to combustion apparatus, and more particularly to fuel combustion apparatus for a gas turbine power plant.

In order to insure eillcient operation of a gas turbine engine of the class comprising a turbinedriven compressor operative to deliver air under pressure to fuel combustion apparatus, it is important to maintain constant and uniform flow not only of the so-called primary air for the support of combustion, but also of the relatively larger volume of secondary air required to effect cooling and protection of the elements and casing structure exposed to the heat of combustion. The state of the primary air has an important bearing in determining the performance of the combustion apparatus with respect to stability or wide range of ignitible mixtures, and compactness of burning. The flame propagation velocity, as well as the range of ignitlble mixtures, for a combustible gas mixture such as air and hydrocarbon vapors, is extended and increased by increasing the temperature of the gases ahead of the reaction zone. The same beneficial effects are realized by preheating the incoming air when fuel is injected into a burner. It has formerly been proposed to realize theadvantages of preheated air in a gas turbine combustion chamber by directing the ilow of substantially all the air in a direction counter to the main flow, along the outside of an interior burner tube or liner, for example. Such an arrangement produces a double reversal in direc- ,provision of improved combustion apparatus adapted to eii'ect flow of secondary air substantially straight through the power plant, and to conduct only the primary air through a tortuous flow path, the primary air being preheated by contact with the burner shell and the shell separating it from the secondary air, while both shells are correspondingly cooled.

A further object of the invention is the provision of improved combustion apparatus in which the ilow path for mixing secondary air with hoty 2 gases or products of combustion is much longer than is the case in conventional types of combustion chambers.

These and other objects are effected by the invention as .will be apparent from the following description and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. 1 is an elevational diagrammatic view. partly in section, of a gas'turbine power plant equipped with combustion apparatus constructed in accordance with one form of the invention;

Fig.'2 is an enlarged-detail sectional view taken substantially along the line II-II of Fig. 1;

Fig. 3 is a fragmentary sectional view in enlarged detail, of a portion of the combustion apparatus shown in Fig. 1

Fig. 4 is a fragmentaryv sectional view of a portion of a combustion apparatus embodying features of the invention in a different form;

Fig. 5 is a fragmentary sectional view, in enlarged detail, taken substantially along the line V-V of Fig. 4;

Fig. 6 is a fragmentary sectional view, in an axial direction, of a combustion apparatus of the cell type embodying features of the invention; and

Fig. 7 is a fragmentary sectional view taken substantially along the line VII-VII of Fig. 6.

Referring to Fig. 1 of the drawings, the gas turbine power plant diagrammatically illustrated therein comprises a substantially cylindrical outer casing structure I0, which is adapted to be mounted in or on the fuselage of an aircraft, and compactly houses operating elements which are constructed and arranged in line in order to present minimum frontal area and drag during operation of the aircraft. Supported within the casing structure l0 is a sectional inner casing structure Il which together with the outer casing structure forms an annular passageway l2, providing a flow communication that extends longitudinally through the engine from a forwardly directed air intake opening I3 to a rearwardly disposed nozzle I4. Mounted within the casing structure lll- Il along the axis thereof are a fairing section- I6, which may contain auxiliary control apparatus (not shown), a multiple stage axial-flow compressor I'l, fuel combustion apparatus generally indicated at I8, and a turbine 20. The rotor of the turbine 20 is operatively connected to the rotor of the compressor I1 through the medium of a common shaft 2|, which is suitably journaled within the inner casing structure Il interiorly of the combustion apparatus I8, on bearings including a bearing 22. The nozzle I4 constitutes the exhaust outlet for the turbine 29, and is preferably annular in form as defined by the terminal edge of the casing structure Il and a centrally disposed cone or core member 24.

According to the well known principle of operation of such a power plant, it will be understood that air entering the intake opening I3 is compressed by the compressor I1 and supplied by way of annular passageway I2 to the combustion apparatus I8 to support combustion of fuel therein, as hereinafter more fully explained. The resultant hot motive fluid under pressure discharged from the combustion apparatus I8 is then expanded through the turbine 20 and is iinally discharged by way of the nozzle I4, usually in the form of a jet establishing a propulsive thrust.

The combustion apparatus I8 is annular in form and is contained within an enlarged portion of the annular passageway I2 deiined between the outer and inner casing sections I and II. As best shown in Fig. 3 of the drawings, the combustion apparatus I8 comprises outer and inner annular walls or shells 26 and 21. which are concentrically spaced apart to form an annular forwardly directed inlet opening 28, the rearwardlydisposed portions of the shells being joined and closed by an annular wall 29. Suitable struts such as the struts 30 may be provided to support the shells 26 and 21 concentrically within the passageway I 2 for dividing the passageway into outer and inner annular passageways I 2a and I2b. Mounted between the outer and inner shells 26 and 21 is a foraminous burner or basket structure comprising outer and inner annular liners or walls 32 and' 33, the rearward ends of which are welded or otherwise secured to the wall 29 and the forward ends of which are joined by a rounded wall 34. An annular combustion chamber 35 is thus formed by the liner walls 32 and 33, which are provided with a plurality of apertures 36 through which the combustion chamber communicates with annular overlapping entryways 38 and 39, which in turn communicate through the inlet 28 with the passage I2.

An annular fuel manifold 40 is suitably supported in the casing structure adjacent the wall 29 of the combustion apparatus, and is adapted to supply fuel in an atomized form to the combustion chamber 35 through the medium of a plurality of nozzles 4 I.

Extending radially through openings in the associated walls 32 and 26, and the walls 33 and 21, respectively, are a plurality of outlet stacks or communications 43, through which products of combustion can be discharged from the combustion chamber 35 to the respective passageways I2a and I2b. The outlet communications 43 are preferably disposed near to or adjacent the forward wall 34. Suitable guide louvres 44 may be provided on the respective shells 26 and 21 to facilitate direction of the products of combustion into the passageways I2a and I 2b in the direction of ow. Although only two stacks or communications 43 are indicated in Fig. 2 of the drawings, it will be understood that the number may be increased in actual practice to provide adequate capacity.

In order to prevent the outer and inner casing structures Il) and II from subjection to excessive heat in the regions of ilow of combustion products through the communications 43, a pair of outer and inner annular baliles or walls 45a and 45h are preferably mounted in parallel alignment within the respective passageways I2a and |26. These baiile's are suiiiciently spaced from the outer and inner casing structures I0 and II to allow streams of cooling or secondary air to ilow through the annular spaces thus formed between the respective baiiles and casing structures.

When the compressor I1 is operated to supply compressed air through the passageway I2, during combustion of fuel supplied to the combustion chamber 35, most of the air under pressure, constituting the secondary air, is allowed to ilow in substantially uninterrupted paths through the passageways |2a and I2b and thence through the remaining portion of passageway I2 to the turbine 20. About twenty-live per cent of the volume of air under pressure, more or less, constitutes the primary air stream, however, which enters the inlet 28 and passes through the outer and inner entryways 38 and 39 and through apertures 36 to the combustion chamber 35 for supporting combustion of fuel therein. In passing through the entryways 38 and 39, this primary air is preheated by virtue of its contact with the liner walls 32 and 33, which are in turn somewhat cooled and thus maintained at a safe temperature. Admission of the preheated primary air under ram pressure, with minimum pulsation, into the combustion chamber 35 is accompanied by vigorous counterilow of the primary air and the fuel spray issued from the nozzles 4I. Flowing forwardly through the combustion chamber 35 toward the wall 34, the hot gases and products of combustion are discharged radially through the communications 43 into the rearwardly owing streams of secondary air passing through the passageways I2a and I2b toward the turbine. With the communications 43 disposed near the forward end of the combustion apparatus, a relatively long mixing path for the secondary air and .I combustion gases is insured, so that by the time the resultant motive iluid enters the turbine blading it has been rendered uniform in velocity and temperature.

If additonal wall cooling appears desirable, a stepped or telescoped construction of the burner shells and of the apertured liners may be substituted for the construction just described. Referring to Fig. 4, such a construction embodying the invention in a different form may comprise outer and inner shells 46 and 41 and outer and inner liners or walls 48 and 49 which are associated in substantially the same manner already described in connection with Fig. 3, to form an annular combustion chamber 50 interposed between entryways 5I and 52. The outer shell 46 may comprise a plurality of annular sections 46a, the adjacent ends of which are suitably formed to enable partial telescoping in association with annular risers 4Gb, which may be corrugated as shown in Fig. 5 and are interposed between the adjacent telescoped ends of the sections 46a to provide openings allowing restricted communication between the respective entryways 5I and 52 and the passageways I2a and I2b. The inner shell 41 may likewise be made up of annular sections having telescoped ends separated by annular risers 41h.

Similarly, the liners 48 and 49 may comprise, respectively, a plurality of apertured sections 48a, the adjacent ends of which are telescoped and separated by annular risers 48h, and concentrically arranged apertured sections 49a and risers 49h. Since the amount of primary air admitted to the combustion chamber 59 will be partially discharged past the respective risers 4Gb, 41h, 48D

and 69h, the quantity of air admitted to the combustor structure should correspondingly be increased by providing an annular inlet 54 of relatively greater ilow area than that of the inlet 28 shown in Fig. 8. Operationy of the combustion apparatus shown in Fig. 4 will readily be understood from the explanation hereinbefore presented.

The features of construction as taught by theA invention may also be embodied in a combustion apparatus of the multiple cell or individual combustion chamber type, such as that illustrated in fragmentary form in Fig. 6 and 7 of the drawings. Referring to Fig. 7, one of a plurality of cells 60 for such a combustion apparatus is illustrated as comprising an outer cylindrical shell 6I suitably supported axially within the annular passageway I2 and spaced from the respective outer and inner casing structures I6 and II. Contained within the cylindrical shell 6I is a smaller tubular combustor or basket structure 62 in which are formed a plurality of apertures 63. The rear ends of the burner tube 62 and shell 6I are joined and closed by a disc or wall 65, and the forward end of the burner tube is similarly closed by a wall 66, which is disposed centrally within an annular entryway 61 communicating with the annular space 68 surrounding the burner tube 62. Radially disposed outlet tubes or communications '69 are provided for connecting the combustion chamber 10, formed within the burner tube 62, with the passageway I2 of the power plant. Extending through the end wall 65 is a fuel nozzle 'I2 through which fuel may be injected in a for-- ward direction into the combustion chamber 16.

It will be understood that operation of each of the plurality of combustion cells 60 will be similar to the functioning of the single annular type of combustion apparatus already described. Thus compressed air initially supplied to the passageway I2 will be divided into secondary air, which flows freely past the cells 60 toward the turbine, and primary air which enters each of the entryways 61 of the cells 6I) for support of combustion within the combustion chambers 'lllthereof. Hot products of combustion are discharged simultaneously from all the combustion chambers into and merged with the secondary air flowing through the passageway I2, thereby insuring thorough mixing and uniform velocity and pressure distribution in the motive fluid supplied to the turbine.

While the invention has been shown in several forms, it will be obvious to those skilled in the artY that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.

What is claimed is: Y

1. Combustion apparatus comprising hollow casing structure having an air inlet and a uid discharge outlet, shell structure openat one end to said air inlet for receiving primary air and closed at the opposite end, said shell structure being spaced within said casing structure to form a substantially unrestricted passage through which secondary air can flow from said inietto said outlet, foraminous liner structure mounted in spaced relation within said shell structure and forming a primary air preheating entryway and a counterflow combustion chamber for processing primary air entering said shell structure from through said passage toward said discharge outlet.

2. In a combustion apparatus, casing structure including exterior and interior sections forming a space having an air inlet and a discharge outlet, combustor structure having outer and inner shells mounted in sai'd space for providing outer and inner passageways communicating with said inlet and outlet, said combustion structure further including a concentric pair of apertured interior walls mounted coaxially between said outer and inner shells to form outer and inner entryways overlapping a combustion chamber, said entryways being open to said air inlet and closed at'the ends adjacent said outlet, annular walls closing the opposite ends of said combustion chamber, nozzles mounted in said casing structure for injecting fuel into one end of said combustion chamber, and a plurality of communications adapted to discharge hot gases from the other end of said combustion chamber into said outer and inner passageways.

3. In a fuel combustion apparatus, casing structure including exterior and interior cylindrical sections forming an annular space having an air inlet and a discharge outlet, combustor structure having outer and inner cylindrical shells mounted in said space for providing outer and inner annular passageways communicating with said inlet and outlet, said combustor structure further including a concentric pair of apertured interior walls mounted coaxially between said outer and inner shells to form outer and inner annular entryways overlapping. an annular combustion chamber, said entryways being open to said air inlet and closed at the opposite ends, annular walls closing the opposite ends of said combustion chamber, nozzles mounted in said casing structure for injecting fuel into the downstream end of said combustion chamber in a direction opposite to that of flow of primary air from said inlet through said entryways, and a plurality of conduits for discharging heated primary air and combustion products from the opposite end of said combustion chamber into the streams of secondary air flowing into said outer and inner passageways.` whereby such primary air is reversed and preheated during-flow through said combustion structure while secondary air traverses relatively unrestricted paths through said outer and inner passageways.

4. Fuel combustion apparatus as specified in claim 3, wherein annular bailies are disposed in y spaced relation with regard to the respective exterior andl interior sections of the casing structure, for maintaining iiow of layers of cool secondary air in protective contact with said casing sections in the regions subject to heat of fluid issuing from said combustion chamber.

5. Fuel combustion apparatus for a power plant of the type including a compressor and a turbine having acommon drive shaft, a cylindrical inl terior casing for containing said shaft and a cysaid inlet, fuel supply means associated with said chamber, and discharge communications Afor di1y recting resultant hot gases from said combustion chamber into the path of secondary air owing lndrical exterior casing surrounding said interior an annular combustor structure having apertured side walls and terminal closure walls forming an annular combustion chamber, said side walls being spaced between said inner and outer shells pressor into said combustion chamber, meansVV for injecting fuel into said combustion chamber, and a plurality ofv communications disposed radially in said-combustor structure for guiding hotgases from said combustion chamber into the upstream ends of said main passages. Y

6. In a fuel combustion apparatus, casing stmoture including exterior and interior cylindrical sections forming an annular space having an air inlet and a discharge outlet, combustor structure having outer and inner cylindrical shells mounted in said space for providing outer and inner annular passageways adapted to conduct secondary cooling air from said inlet substantially straight throughsaiddngstruchiretosaidwtlta combustor basket structure mounted within said outer and inner shells, means for injecting fuel into said basket structure, said shells and basket .structure being adapted to divert primary air drawn-from saidinlet through a countei'ow path for'absoa'bing heat from said shells and "facilitating combustion. of fuel wlthinsaid basket structure, and a plurality of radially disposed communications for merging resultant hot gases from said. basket structure into the streams ot secondary air flowing through said outer and inner passageways.

v STEWART WAY.

No references cited.

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