US3899876A

US3899876A - Flame tube for a gas turbine combustion equipment

Info

Publication number: US3899876A
Application number: US876504A
Authority: US
Inventors: Douglas H Williamson
Original assignee: UK Secretary of State for Defence
Current assignee: UK Secretary of State for Defence
Priority date: 1968-11-15
Filing date: 1969-11-13
Publication date: 1975-08-19
Anticipated expiration: 1992-08-19
Also published as: FR2023415A1; DE1957147A1

Abstract

A flame tube for gas turbine combustion equipment includes at least one wall of double-skinned construction having internal and external skins throughout the major part of its longitudinal and peripheral extent, the internal skin comprising a plurality of axially consecutive peripherally extending sections attached to the external skin at their upstream ends only and being spaced from the external skin to define respective passages therebetween, each section except the most downstream section extending downstream to the upstream end of the next section, the external skin being apertured to direct in operation jets of cooling air onto the internal skin sections for impingement cooling thereof, said cooling air thereafter flowing through said passages.

Description

United States Patent Williamson Aug. 19, 1975 FLAME TUBE FOR A GAS TURBINE 3,362,470 1/1968 Richardson 60/3965 COMBUSTION EQUIPMENT 3369363 2/1968 60/3965 3,384,346 5/1968 (SO/39.66 [75] Inventor: Douglas H. Williamson, Derby, 14413 6/1969 60/3965 England 3,570,241 3/1971 Alexander 60/3965 [73] Assignee: The Secretary of State for Defence in Her Britannic Majestys Primary ExaminerDoug1as Hart Government f the United Kingdom Attorney, Agent, or Firm-Cushman, Darby & of Great Britain and Northern Cushman Ireland, London, England 122 Filed: Nov. 13, I969 1 1 ABSTRACT [2]] Appl NO; 876,504 A flame tube for gas turbine combustion equipment includes at least one wall of double-skinned construction having internal and external skins throughout the 1 1 Foreign Applicafion Priority Data major part of its longitudinal and peripheral extent,

Nov. 15, 1968 United Kingdom 54398/68 the internal skin comprising a plurality of axially consecutive peripherally extending sections attached to [52] US. Cl, 60/39.66; 60/3965; 431/352 the external skin at their upstream ends only and [51] Int. Cl. F02c 7/18; F23r 1/10 being spaced from the external skin to define respec- [58] Field of Search 60/3965, 39.66; 431/350, tive passages therebetween, each section except the 431/351, 352 most downstream section extending downstream to the upstream end of the next section, the external skin [56] References Cited being apertured to direct in operation jets of cooling UNITED STATES PATENTS air onto the internal skin sections for impingement 2,657,531 11 1953 Pierce 60/3966 Cooling h Said Cooling air themafter flowing 2,760,335 8/1956 GOddklrd.... 60 3974 through Passages- 2,919,549 1 1960 Haworth.... 60 3966 3,349,558 10/1967 Smith 60 3965 14 Clams 5 Drawmg F'gures PATENTED Ans-1 9191s SHEET 1 o 3 Inventor PATENTED AUB1 91975 SHEET 2 OF 3 m/FJ. II \lll/ 441 W By 0 J J W Attorneys PATENTEU 1 9 75 SHEET3UE3 Inventor Maj MM y Z Z Attorneys FLAME TUBE FOR A GAS TURBINE COMBUSTION EQUIPMENT This invention relates to flame tubes for gas turbine engine combustion equipment.

The invention is directed to any novel feature or combination of features herein described and/or shown in the drawings.

Although not so restricted thereto, the invention provides in one aspect a flame tube for gas turbine combustion equipment, the flame tube including at least one wall of double'skinned construction having inter ha] and external skins throughout the major part of its longitudinal and peripheral extent, the internal skin comprising a plurality of axially consecutive peripherally extending sections attached to the external skin at their upstream ends only and being spaced from the external skin to define respective passages therebetween, each section except the most downstream section extending downstream to the upstream end of the next section, the external skin being apertured to direct in operation jets of cooling air onto the internal skin sections for impingement cooling thereof, said cooling air thereafter flowing through the said passages.

The passages may be open at their downstream ends to direct said flow of cooling air across the internal surface of the flame tube wall to effect film cooling thereof.

There may be spacers adapted to maintain the downstream ends of the said sections of internal skin spaced from the external skin whilst permitting sliding movement of said downstream ends relative to the external skin and relative to other sections of internal skin.

Each spacer may be peripherally substantially coextensive with a respective internal skin section by which it is carried and may be apertured to permit said flow of cooling air.

Alternatively, the spacers may comprise for each said section a plurality of angularly spaced apart protuberances on a said skin which project towards the other said skin.

The protuberances may be blisters on the sections of internal skin, there being apertures to permit the flow of cooling air in the said passage to pass both internally and externally of the blisters.

The inner skin may be made of a porous material for effusion or transpiration cooling thereof.

The external skin may comprise a plurality of axially consecutive rings a downstream ring being of diameter such that it is disposed outwardly, with respect to the interior of the flame tube, of an immediately upstream ring, the downstream ring having axially aligned therewith a said internal skin section which is attached only to the said immediately upstream ring.

Alternatively, the external skin may comprise a plurality of axially spaced rings each integrally formed and bifurcated at its downstream end to provide a respective pair of radially spaced axially extending annular flanges, the outer flange of at least one ring, relative to the interior of the flame tube, being attached to the upstream end of the next downstream ring, the other flange of the at least one ring having fixedly attached thereto the upstream end ofa said internal skin section.

There may be radially extending flanges at the upstream end of the flame tube which are adapted to support fuel injector means, said flanges being provided with a downstream'facing heat shield.

The flame tube may be provided at its downstream end with a discharge nozzle of double-skinned construction having internal and external skins.

There may be apertures to permit cooling air to pass in an upstream direction between the internal and external skins of the discharge nozzle to effect cooling thereof and means to thereafter direct said cooling air downstream across the internal surface of the discharge nozzle wall to effect cooling thereof.

The most downstream internal skin section of the flame tube wall may overlap a spigot connection between the flame tube and the discharge nozzle, to shield it from the interior of the flame tube.

The invention also provides in another aspect, to which it is not restricted, a gas turbine engine having a flame tube as set forth above.

The invention will be described, merely by way of example, with reference to the accompanying drawings, wherein:

FIG. 1 is a longitudinal section of part of a gas turbine engine having a flame tube according to the invention,

FIG. 2 is a similar section through a different form of flame tube according to the invention,

FIG. 3 is a scrap section on line 3-3 of FIG. 2,

FIG. 4 is a view on arrow 4 of FIG. 3, and

FIG. 5 is a scrap longitudinal section of a further flame tube according to the invention.

Referring to FIG. 1, a gas turbine engine (not shown complete) has a main flow duct 11 in which is mounted, in axial flow series, compressor means of which the downstream-most rotor stage 13 is shown, combustion equipment 14 and a turbine stage 16 which is drivingly connected with the compressor 13 by means of conventional shafting (not shown). Axially between the compressor stage 13 and the combustion equipment 14 there is provided a ring of outlet guide vanes 17, and upstream of the turbine stage 16 there is provided a ring of inlet guide vanes 19.

The combustion equipment 14 comprises an annular combustion chamber 20 in which is located an annular flame tube 22. In operation, compressed air from the compressor means 13 enters the combustion chamber 20, after having passed through the outlet guide vanes 17, and passes into the flame tube 22 through conventional primary, secondary and tertiary

air inlet chutes

21, 23 and 25 respectively. Fuel is injected into the flame tube 22 in operation by one or more injector nozzles (not shown), and the fuel and air mixture is ignited. The products of combustion leave the flame tube 22 at its downstream and via a discharge nozzle 26 and pass to the inlet guide vanes 19 of the turbine 16. The discharge nozzle 26 is connected to the flame tube via radially inner and outer stellite-coated spigot rings 26a, 26b which permit relative movement of the flame tube and the discharge nozzle.

During the combustion of the fuel air mixture, the flame tube walls get extremely hot, and flame tubes 22 of conventional materials have a limited life.

In order to increase the operational lifetime of a flame tube, the flame tube 22 including its discharge nozzle 26 is provided with a double-skinned construction substantially throughout its length and periphery. The annular flame tube 22 has a radially outer wall 27 and a radially inner wall 28, each having a respective internal skin 30 and an external skin 32.

The upstream end of each internal skin 30 is provided with a radially extending flange or flanges 33 be- "arugula:

tween which may be located a fuel injector (not shown) and through which primary air may pass into the interior of the flame tube 22. Moreover, if desired, swirl vanes may also be mounted from the flanges 33. A downstream-facing heat shield 33a is provided to protect the flanges33, which otherwise would be exposed to high temperatures as well as the stresses involved in supporting the injectors,

It is to be noted that the double-skinned construction of the flame tube 22 extends between the radial planes of the upstream-most parts of the flanges 33 and the plane just upstream of, or substantially coplanar with, the upstream edge of the inlet guide vanes 19.

The internal skins comprise a plurality of axially consecutive portions the upstream end only of each of which is attached, preferably by welding, to the re spective external skins 32. The external skins 32 each consist of two axially

consecutive rings

32a, 32b, the downstream ring being of a diameter such that it is disposed outwardly with respect to the flame tube of the immediately upstream ring 32a. In this embodiment the rings are integrally formed with each other.

There are upstream and downstream internal skin sections 35, referenced as 35a, 35b. The upstream sections 35a extend downstream to the upstream end of the downstream section 35b. The downstream sections 35b are aligned with the downstream external skin rings 32b and are attached to the downstream ends of the upstream rings 32a only.

The internal skin sections 35 are spaced from the external skin to define passages 31 therebetween. In this embodiment, the spacing is maintained at not less than a minimum amount by means of spacers 36 which are carried by and are peripherally coextensive with the internal skin sections 35. Each spacer 36 is integrally formed with the skin section 35 by which it is carried. If the spacers were not provided, there may be a tendency for one or more of the passages 31 to be closed up if the flame tube were to distort due to a hot spot therein.

The spacers 36 are not attached to the respective outer skins 32 but are fitted by an interference fit sliding joint and are provided with a coating, e.g. a plasmasprayed stellite coating. This allows relative thermal expansion between the respective inner and outer skins, and assures good resistance to frettage-wear.

The external skins 32 are provided with a large number of apertures 34 which are adapted to direct a flow of cooling air so as to impinge on the radially outer surfaces of the internal skins 30 via the passages 31. The apertures 34 direct jets of cooling air onto the surface of the internal skins 30 at a substantial angle thereto, thereby to effect impingement cooling of the skins 30.

The spacers 36 are also provided with a number of

apertures

37, 37a to allow the cooling air to pass therethrough and into the interior of the flame tube 22 from the passages 31. The apertures 37 direct cooling air emerging therefrom across and along the internal surface of the internal skin section 35b to effect film cooling thereof. Likewise, the apertures 37a direct cooling air across and along the internal surface of the flame tube to effect film cooling thereof.

The external skin 32 of the discharge nozzle 26 is provided at least at its downstream end with apertures 40 which permit cooling air to pass into the passages 31 between the skins of the discharge nozzle wall to effect cooling thereof. The apertures 40 are preferably such that said cooling is effected at least partially by impingement cooling of the internal skin 30.

Further apertures 42 are provided in the upstream portions of the internal skins 30 of the discharge nozzle walls. Cooling air passes via the apertures 42 from the passages 31 in the discharge nozzle walls into the interior of the flame tube where it is directed by deflector plates 46 to pass downstream across the internal surface of the discharge nozzle walls to effect cooling, preferably film cooling thereof, additionally to cooling which may be effected by cooling air leaving the apertures 37a.

Referring to FIG. 2, there is shown a different flame tube according to the invention. Parts similar to those of FIG. I carry the same reference numerals and will not be described again. Only the points of'difference will be detailed.

The FIG. 2 embodiment differs from the FIG. 1 embodiment in that there are three axially

consecutive rings

50, 52, 54 in the radially outer and radially inner walls, each having a respective

internal skin section

56, 58, 60 aligned therewith. There is also an additional internal skin section 61 at the downstream radially outer end of the flame tube.

A

short length

62, 64 of both the radially outer and radially inner

flame tube walls

27, 28 at the upstream ends thereof are of single-skin instead of double-skin construction, because in this version it is considered preferable to rely at this region on the external convective cooling provided by the air flowing to the secondary and

tertiary air chutes

23, 25 since here there is insufficient pressure difference between the inside and the outside of the flame tube to permit efficient impingement cooling.

Instead of the peripherally coextensive spacers 36 there are provided a plurality of angularly spaced apart protuberances on the inner skin, in the form of partcylindrical blisters 66, best seen in FIG. 3. The blisters all project towards the outer skin 32, and a respective aperture 68 is provided in the internal skin sections immediately upstream of each blister to permit the flow of cooling air in the passages 31 to pass both internally and externally of the blisters 66 to film-cool them. The slots bite into the adjacent blisters so that, as can be seen from FIG. 2, the leading faces of the blisters act as scoops.

The additional internal skin section 61 is provided instead of one of the deflector plates 46 of the FIG. 1 embodiment. The section 61 is similar to the

sections

56, 58, 60, and not only directs the cooling air issuing from the apertures 42, but also shields the radially outer spigot ring 26b which at this part of the flame tube forms the radially outer external skin. A similar extra internal skin section may if desired be provided in place of the radially inner plate 46.

FIG. 5 shows an alternative form of the flame tube according to the invention. The external skin 32, of which the radially outer one only is shown in FIG. 5, comprises a plurality of integrally formed (e.g. machined) rings 70, 71 each bifurcated at its downstream end to provide a respective pair of axially extending radially spaced

annular flanges

72, 74. The outer flange 72 (relative to the interior of the flame tube) of the ring is butt-welded to a cylindrical section which itself is butt-welded to the upstream end of the ring 71. The flanges 74 each support an

internal skin section

58, 60 etc., being butt-welded thereto.

In any of the described embodiments, the internal skins 30 of the flame tube, including those of the discharge nozzle 26, may be made of a porous material so as to allow these skins to be effusion or transpiration cooled in addition to the impingement cooling described so far. Effusion or transpiration cooling may be considered to be more efficient than merely impingement cooling because its mechanism may be separated into two parts, namely a heat exchange between the porous material and the coolant as the latter permeates through the porous material, and an insulation effect which results from the mass transfer across the boundary of the material.

Preferably, most of the pressure drop across the flame tube wall is arranged to occur across the outer skin. The consequent relatively small pressure drop across the internal skin means that pressure stresses in the hot internal skin are much reduced or minimised. This in turn results in an increase in the life of the flame tube, or alternatively it allows the operating temperature of the internal skin to be increased. It also may improve the impingement cooling efficiency.

It will be appreciated that although the invention has been described with reference to annular flame tubes, it is also applicable to the can-type of flame tube.

I claim:

l. A flame tube for gas turbine combustion equipment, the flame tube including at least one wall of double-skinned construction having internal and external skins throughout the major part of its longitudinal and peripheral extent, the internal skin comprising a plurality of axially consecutive peripherally extending sec tions, means attaching each section by its upstream end only to the external skin, each section being spaced from the external skin to define respective passages therebetween, each section except the most downstream section extending downstream to the upstream end of the next section, the external skin having apertures therein, said apertures directing jets of cooling air onto the internal skin sections for impingement cooling thereof, the passages accommodating a flow of said cooling air which has cooled the internal skin sections.

2. A flame tube as claimed in claim 1 wherein the internal skin sections and the external skin define openings at the downstream ends of said passages, said openings directing said flow of cooling air across the internal surface of the flame tube wall, effecting film cooling thereof.

3. A flame tube as claimed in claim 1 comprising spacers maintaining downstream ends of the said sections of internal skin spaced from the external skin while permitting sliding movement of said downstream ends relative to the external skin and relative to the other sections of internal skin.

4. A flame tube as claimed in claim 3 wherein each spacer is peripherally substantially coextensive with a respective internal skin section, said respective internal skin section supporting the spacer coextensive therewith, the spacers having apertures therein permitting said flow of cooling air.

5. A flame tube as claimed in claim 3 wherein the spacers comprise for each said section a plurality of angularly spaced apart protuberances on a said skin which project towards the other said skin.

ti. A flame tube as claimed in claim 5 wherein the protuberances are blisters on the sections of internal skin, the sections of internal skin having apertures permitting the flow of cooling air in the said passage to pass both internally and externally of the blisters.

7. A flame tube as claimed in claim 1 wherein the inner skin is made of a porous material for effusion or transpiration cooling thereof.

8. A flame tube as claimed in claim 1 wherein the external skin comprises a plurality of axially consecutive rings, a downstream ring being of diameter such that it is disposed outwardly, with respect to the interior of the flame tube, of an immediately upstream ring, a said internal skin section being axially aligned with the downstream ring, and having means attaching it only to the said immediately upstream ring.

9. A flame tube as claimed in claim 1 wherein the external skin comprises a plurality of axially spaced rings each integrally formed and bifurcated at its downstream end to provide a respective pair of radially spaced axially extending annular flanges, means attaching the outer flange relative to the interior of the flame tube, of at least one ring, to the upstream end of the next downstream ring, and means attaching the other flange of the at least one ring to the upstream end of a said internal skin section.

10. A flame tube as claimed in claim 1 comprising radially extending flanges at the upstream end of the flame tube which are adapted to support fuel injector means, said flanges being provided with a downstreamfacing heat shield.

11. A flame tube as claimed in claim 1 and provided at its downstream end with a discharge nozzle of double-skinned construction having internal and external skins.

112. A flame tube as claimed in claim 11 wherein the discharge nozzle has apertures to permit cooling air to pass in an upstream direction between the internal and external skins of the discharge nozzle, effecting cooling thereof, and means to thereafter direct said cooling air downstream across the internal surface of the discharge nozzle wall, effecting cooling thereof.

13. A flame tube as claimed in claim 11 comprising a spigot connection between the flame tube and the discharge nozzle, the most downstream internal skin section of the flame tube wall overlapping said connection, shielding it from the interior of the flame tube.

14. A gas turbine comprising in flow series compressor means, combustion equipment and turbine means, the combustion equipment comprising a flame tube including at least one wall of double-skinned construction having internal and external skins throughout the major part of its longitudinal and peripheral extent, the internal skin comprising a plurality of axially consecutive peripherally extending sections, means attaching each section by its upstream end only to the external skin, each section being spaced from the external skin to define respective passages therebetween, each sec tion except the most downstream section extending downstream to the upstream end of the next section, the external skin having apertures therein, said apertures directing jets of cooling air onto the internal skin sections for impingement cooling thereof, the passages accommodating a flow of said cooling air which has cooled the internal skin sections.

Claims

1. A flame tube for gas turbine combustion equipment, the flame tube including at least one wall of double-skinned construction having internal and external skins throughout the major part of its longitudinal and peripheral extent, the internal skin comprising a plurality of axially consecutive peripherally extending sections, means attaching each section by its upstream end only to the external skin, each section being spaced from the external skin to define respective passages therebetween, each section except the most downstream section extending downstream to the upstream end of the next section, the external skin having apertures therein, said apertures directing jets of cooling air onto the internal skin sections for impingement cooling thereof, the passages accommodating a flow of said cooling air which has cooled the internal skin sections.

6. A flame tube as claimed in claim 5 wherein the protuberances are blisters on the sections of internal skin, the sections of internal skin having apertures permitting the flow of cooling air in the said passage to pass both internally and externally of the blisters.

10. A flame tUbe as claimed in claim 1 comprising radially extending flanges at the upstream end of the flame tube which are adapted to support fuel injector means, said flanges being provided with a downstream-facing heat shield.

12. A flame tube as claimed in claim 11 wherein the discharge nozzle has apertures to permit cooling air to pass in an upstream direction between the internal and external skins of the discharge nozzle, effecting cooling thereof, and means to thereafter direct said cooling air downstream across the internal surface of the discharge nozzle wall, effecting cooling thereof.

14. A gas turbine comprising in flow series compressor means, combustion equipment and turbine means, the combustion equipment comprising a flame tube including at least one wall of double-skinned construction having internal and external skins throughout the major part of its longitudinal and peripheral extent, the internal skin comprising a plurality of axially consecutive peripherally extending sections, means attaching each section by its upstream end only to the external skin, each section being spaced from the external skin to define respective passages therebetween, each section except the most downstream section extending downstream to the upstream end of the next section, the external skin having apertures therein, said apertures directing jets of cooling air onto the internal skin sections for impingement cooling thereof, the passages accommodating a flow of said cooling air which has cooled the internal skin sections.