EP1619441A1 - Gas turbine engine with protection means for a fuel injector, fuel injector and protection foil. - Google Patents

Abstract

The engine has a gas flow reheating duct with an afterburner flame holder arm (8) having an open enclosure. The enclosure has a wall (8`) within which a fuel injecting tube (8b), injecting a fuel (10) in a direction, is extended. The arm has a radial cooling jacket (8a) in a side of the wall forming a U shaped section, and a protection foil (8d) interposed between the tube (8b) and the wall, in the direction of fuel injection.

Description

The invention relates to a turbojet comprising a heating channel of the primary gas flow, with a fuel injection device and protection means for the fuel injection device. The invention also concerns, as intermediate products, a fuel injection device and a protective sheet for said turbojet engine.

The so-called "afterburner" turbojets generally comprise, upstream to downstream in the direction of gas flow, one or more compressor stages, a combustion chamber, one or more turbine stages, a heating channel or channel afterburner, and an ejection nozzle. The flow of primary gas, downstream of the turbine stages, allows a new combustion, thanks to the oxygen still present within it, in the heating channel before relaxing in the ejection nozzle.

At the entrance of the heating channel, flame-holder arms extend radially in the gas flow. They are generally U-shaped section, the branches of the U being oriented downstream, and comprise within them a fuel injector projecting the latter into the gas vein, towards the downstream. The fuel is ignited and the flames are, due to the shape of the section of the arms, causing a depression, hanging on the walls of the arms. A flame ring, concentric with the casing of the heating channel, can also be provided in the gas stream of the primary flow. It works according to the same principle.

The primary flow is at a temperature of about 950 ° C. The walls of the flame holder arms, although cooled by a jacket supplied with air from the secondary air stream at 200 or 250 ° C, are at a temperature of around 800 to 850 ° C, especially at their trailing edge. , while the flames hung on the arms are at a temperature of 1700 ° C. The fuel is thrown at a temperature of about 100 ° C, more precisely between 50 and 150 ° C, against the walls of the arm at 850 ° C.

The thermal gradients resulting from this impact are very important, and cause deformations of the arms, especially at their trailing edge. Their life is therefore reduced, which is all the more damaging as the arms are generally from the foundry, in Colbalt-based alloys, and are difficult to replace. Maintenance costs are therefore very high.

US 5, 179, 832 proposes, in the case of an annular injection device having two walls forming an enclosure open upstream and downstream, a protective sheet adjacent to the outer wall, against which is projected the fuel . The fuel is thrown by a remote fuel injector tube on the inner side of the upstream opening of the enclosure. Such protection is however not satisfactory in the case of a closed enclosure on the upstream side.

The present invention aims to overcome these disadvantages.

For this purpose, the invention relates to a turbojet, comprising a gas flow heating channel, the heating channel comprising at least one fuel injection device in the gas stream, which comprises an open chamber, having a section U-shaped, comprising at least one wall and within which extend fuel injection means, which inject the fuel in at least one direction, characterized in that a cooling jacket is provided in the enclosure, on the side of the wall forming the base of its U-shaped section, and the fuel injection device comprises protective means interposed between the fuel injection means and the wall, in a direction of injection of fuel.

Preferably, the protection means comprise at least one sheet.

More preferably, the injection device is in the form of a radial arm.

Advantageously in this case, the protection means extend along the entire radial height of the arm.

Still preferably, the fuel injection means comprise at least one tube, supplied with fuel and having fuel injection orifices.

Advantageously, the fuel injection device further comprising a protective screen, placed in the opening of the enclosure, the protection means are positioned between a wall of the enclosure and the protective screen.

According to one embodiment, the fuel injection means are placed between the walls forming the branches of the U-shaped section of the enclosure.

Preferably in this case, a sheet is placed substantially parallel to each of the walls of the enclosure forming the branches of its U-section.

According to one embodiment, each sheet is fixed to the wall to which it is substantially parallel.

In another embodiment, each sheet is attached to the cooling jacket.

According to another embodiment, the sheet metal has a U-section, obviously a radial one, in the central part of the wall forming the base of its U-section, which is slid on a slide-forming piece, integral with the cooling jacket. .

As an intermediate product, the invention also relates to a fuel injection device for the turbojet engine above.

As an intermediate product, the invention also relates to a protective sheet for a fuel injection device for the turbojet engine above.

• la figure 1 représente une vue partielle en coupe axiale de la forme de réalisation préférée du turboréacteur de l'invention ;
• la figure 2 représente une vue en coupe transversale du turboréacteur de la figure 1, suivant la direction A-A ;
• la figure 3 représente une vue agrandie de la zone de la figure 1 contenue dans le cadre C ;
• la figure 4 représente une vue en coupe du bras accroche-flammes de la figure 3, suivant la direction B-B ;
• la figure 5 représente une vue en coupe du bras accroche-flammes de la figure 4, suivant la direction C-C ;
• la figure 6 représente une vue en coupe d'une deuxième forme de réalisation du bras accroche-flammes du turboréacteur de l'invention ;
• la figure 7 représente une vue en coupe d'une troisième forme de réalisation du bras accroche-flammes du turboréacteur de l'invention ;
• la figure 8 représente une vue de profil schématique d'une forme de réalisation particulière de la tôle de protection du bras accroche-flammes du turboréacteur de l'invention et
• la figure 9 représente une vue en coupe schématique d'une autre forme de réalisation particulière de la tôle de protection du bras accroche-flammes du turboréacteur de l'invention.

The invention will be better understood with the aid of the following description of the preferred embodiment of the turbojet engine of the invention, with reference to the attached plates, in which:

• FIG. 1 represents a partial view in axial section of the preferred embodiment of the turbojet engine of the invention;
• FIG. 2 represents a cross-sectional view of the turbojet engine of FIG. 1, in the direction AA;
• FIG. 3 represents an enlarged view of the area of FIG. 1 contained in frame C;
• Figure 4 shows a sectional view of the flame holder arm of Figure 3, in the direction BB;
• FIG. 5 represents a sectional view of the flame-holder arm of FIG. 4, in the direction CC;
• FIG. 6 represents a sectional view of a second embodiment of the flame-holder arm of the turbojet engine of the invention;
• FIG. 7 represents a sectional view of a third embodiment of the flame-holder arm of the turbojet engine of the invention;
• FIG. 8 represents a schematic side view of a particular embodiment of the protective plate of the flame-holder arm of the turbojet engine of the invention and
• FIG. 9 represents a schematic sectional view of another particular embodiment of the protective plate of the flame-holder arm of the turbojet engine of the invention.

With reference to FIG. 1, the turbojet engine 1 of the invention, which extends along an axis 1 ', comprises a plurality of compressor stages 2, a combustion chamber 3, several turbine stages 4, a heat flux channel 5 and an ejection nozzle 6. The heating channel 5 is delimited by an inner liner 5 'enveloped by an outer casing 5 ".These two elements 5', 5" delimit between them a passage for cooling air. cooling.

At the inlet of the heating channel 5, radially extending fuel injector arms 7, integral with the outer casing 5 "and the inner liner 5 'of the heating channel 5. The function of the injectors is to vaporize fuel towards flame holder arms 8, situated downstream in the heating channel 5.

Referring to Figure 2, the flame holder arms 8 are the same number, here nine, the fuel injector arms 7 and are angularly offset from them, so that in front view, each fuel injector arm 7 is located between two neighboring flame holder arms 8, equidistant from them. The fuel injector arms 7 are radially smaller than the flame holder arms 8.

In the vicinity of the inner jacket 5 'of the heating channel 5, in the heating channel of the primary flow 5, the flame holder arms 8 support a flame holder ring 9. This ring 9 is made up of a plurality of 9 'ring portions, here nine in number, which extend concentrically to the casings 5', 5 "of the heating channel 5, between two flame-holder arms 8 successive.

With reference to FIG. 3, a fuel injector arm 7 comprises a radial cooling sleeve 7a extending over the entire radial height of the arm 7, parallel to which extends, downstream, a fuel injector tube 7b, fueled from the outside of the outer casing 5 "of the heating channel 5 and having fuel vaporization ports, the cooling jacket 7a is supplied with cooling air, taken from the secondary air flow, and has orifices. allowing the arm 7 to be cooled by air impingement The fuel injector arms 7 extend radially perpendicularly to the axis 1 'of the turbojet engine 1.

The flame-holder arms 8 extend radially, inclined downstream, from their base integral with the outer casing 5 "of the heating channel 5, with respect to the perpendicular to the axis 1 'of the turbojet engine 1 contained in FIG. the axial plane of the arm 8. A flame-holder arm 8 comprises an open enclosure delimited by walls 8 '- which can be replaced in a similar manner by a continuous wall 8' - in which are contained its various elements. flame comprises a radial cooling jacket 8a, extending over the entire radial height of the arm 8, parallel to which extends, downstream, a fuel injector tube 8b, supplied with fuel from outside the outer casing 5 "and having fuel jet orifices.

The simplified operation of the turbojet engine is as follows. Fuel is vaporized by the fuel injector tubes 7b of the fuel injector arms 7 and by the fuel injector tubes 8b of the flame holder arms 8. This fuel undergoes, thanks to the residual oxygen of the primary gas flow, also thanks to to a supply of air from the secondary flow, a combustion. This combustion occurs at the level of flame-holder arms 8, the shape of which causes the flames to be held by said arms 8. This combustion, called post combustion or heating, provides an additional thrust to the turbojet engine. This post combustion process is well known to those skilled in the art and will therefore not be detailed more precisely. The gas then relaxes in the heating channel 5 and in the ejection nozzle 6 before being ejected from the turbojet engine 1.

Referring to Figure 4, the outer walls 8 'of a flame holder arm 8, defining its open enclosure, have a U-shaped section, whose branches are facing downstream. More precisely, the branches of the U are not parallel; it would be more of a V with a rounded base; it will be mentioned in the following section U. The cooling jacket 8a occupies the upstream portion of this U-section, that is to say its closed portion. This jacket 8a has a plurality of orifices, typically nine hundred, through which is projected the air of the secondary flow with which it is fed, to cool the walls 8 'of the arm 8. Just downstream, centered by relative to the walls 8 'extends the fuel injector tube 8b. Downstream of this tube 8b extends a protective screen 8c, also of U-shaped section, whose function is to protect the fuel injector tube 8b and the cooling jacket 8a of the flame attached to the trailing edges of the walls 8 'of the arm 8. This screen 8c occupies almost all the space left between the end of the walls 8' of the arm 8 forming the branches of its U-section.

A protective plate 8d extends between the walls of the protective screen 8c and the walls 8 'of the arm 8. Its function is to prevent a direct impact of the fuel on the walls 8' of the arm 8, the disadvantages of which have been presented above. In the embodiment of Figure 4, the flame holder arm 8 comprises two protective plates 8d, extending substantially parallel to the two walls 8 'forming the branches of the U-section of the arm 8, since the cooling jacket 8a, without being in contact with it and forming in its vicinity a slight elbow towards the inside of the arm, to the trailing edges of the arm 8. The plates 8d extend over the entire radial height of the arm 8.

Thus, the fuel, shown schematically by dashed lines 10, is projected from the fuel injector tube 8d onto the protective plates 8d, before being ejected, between said plates 8d and the protective screen 8c, out of the arm 8, where he is inflamed.

FIG. 5 shows the method of fixing a protective plate 8d within an arm 8. The protective plate 8d is fixed to the wall 8 'of the arm 8, to which it is substantially parallel, by means of fixing pins 11 passing through holes provided for this purpose in the sheet 8d and the wall 8 '. In order to maintain a sufficient spacing between the wall 8 'of the arm 8 and the protective plate 8d, spacing required for a certain thermal independence between these two elements and therefore to an acceptable protection of the wall 8 'of the arm 8, spacers 12 are positioned between their surfaces facing one another, around the fixing pins 11.

The protective screen 8c is fixed to the protective plate 8d at its wall portions corresponding to the branches of its U-section, by the same fixing pins 11. Such wall portion is generally in the form of a plate, having recesses 13 in which are drilled through holes fixing pins 12. Thus, the screen 8c is plated on the sheet 8d at the recesses 13, while the bulk of its surface is discarded of the sheet 8d, so as to leave a passage space for the fuel 10.

The fixing pins 11 are arbitrary and will be chosen by those skilled in the art.

Thanks to the protective plates 8d, the fuel 10 projected by the tube 8b does not come into contact with the walls 8 'of the arm 8, whose temperature is very important, avoiding them to undergo a too great thermal gradient. It is projected on the protective sheets 8d, which are within the space defined by the walls 8 'of the arm 8 and are at a lower temperature, thanks in particular to the cooling provided by the jacket 8a. Their temperature is typically 600 to 650 ° C, instead of 850 ° C for the walls 8 'of the arm 8. The thermal gradient to which they are subjected is less important. The sheets 8d may be made of any suitable material, for example metal, ceramic or ceramic matrix components (CMC).

The sheets 8d thus protect the walls 8 'of the arm 8, since they are placed between the tube 8b and the walls 8' of the arm, in the fuel injection direction; they undergo deformations, but once deformed they are easily replaceable, at least more easily than the walls 8 'of the arm 8, which ensures lower maintenance costs than for the structures of the prior art.

Other methods of attachment and other forms of the protective plates 8d are conceivable.

Referring to Figure 6, a sheet 8d can be directly attached to the cooling jacket 8a. In this case, the arm 8 comprises two protective plates 8d, extending substantially parallel to the two walls forming the branches of the U-section of the arm 8, these two plates 8d being fixed to the cooling jacket 8a of the arm 8, in its downstream portion. The attachment can be obtained by any means of attachment. The sheets 8d preferably extend to the trailing edges of the arm 8, over its entire radial height. The sheets 8d can be, on the one hand, fixed to the cooling jacket 8a, on the other hand, fixed to the walls 8 'of the arm 8, for example in the same way as previously. The operation of the arm 8 and the protection of the walls 8 'by the protective plates 8d are similar to those described above. The advantage of this solution is the continuity between the protective plates 8d and the cooling jacket 8a, excluding any possible contact between the fuel and the walls 8 'of the arm 8.

With reference to FIG. 7, it is possible to provide a U-shaped sheet metal 8d, having a radial recess 15 in the central part of the wall forming the base of its U-section, extending from a radial end of the plate 8d. almost to its other radial end. The sheet 8d is slid into a T-section part 14, integral with the cooling jacket 8a by the base of the T. This part 14 thus forms a slide for the protective plate 8d, at its recess 15, which is slid until its non-recessed radial end comes into abutment on the piece 14. It can be locked to the piece 14. Thus, the protective plate 8d protects not only the walls 8 'of the arm 8 by the walls forming the branches of its U-section, extending to the trailing edge of the arm 8, but also the cooling jacket 8a by the wall forming the base of its U-section, completed by the wall of the slide 14 forming the bar of its section T. The operation of the arm 8 and its protection by the protective plate 8d are also quite comparable to what has been seen previously. The advantage of this embodiment of the protective plate 8d is its ease of replacement, by simple translational movement in the slide 14. The sheet 8d is furthermore as a single piece, to protect all the walls 8 'of the arm 8.

In order to increase its life, the protective plate 8d, in its downstream region close to a trailing edge of the arm 8 may be, whatever its overall shape, shaped differently than a simple plate.

Referring to Figure 8, the downstream end wall of the protective plate 8d may include slots 16, which can absorb the deformations to which the sheet 8d is subjected. These slots 16 may optionally be completed by circular recesses 17 at their upstream end, which allow greater deformation of the sheet portions 8d located between two slots 16.

According to another embodiment, the walls of the sheet 8d may have, in their downstream end portion, or even over their entire wall substantially parallel to a wall 8 'of the arm 8, a section, sectional view transverse to the overall plane of the wall, of corrugated shape, which absorbs the deformations related to thermal gradients. Indeed, this type of undulations is generally the result of deformations; the fact of providing them in advance allows somehow to pre-constrain the sheet 8d.

The invention has been presented in connection with a fuel injection device in the primary gas flow which is a radial arm, but it goes without saying that the invention applies to any type of fuel injection device in the primary gas stream, including a ring.

Claims (16)

Turbeactor, comprising a gas flow heating channel (5), the heating channel (5) comprising at least one fuel injection device (8) in the gas stream, which comprises an open chamber, having a section U-shaped, comprising at least one wall (8 ') and within which extend fuel injection means (8b), which inject the fuel (10) in at least one direction, characterized in that that a cooling jacket (8a) is provided in the enclosure, on the side of the wall (8 ') forming the base of its U-shaped section, and the fuel injection device (8) comprises means of protection (8d) interposed between the fuel injection means (8b) and the wall (8 '), in a fuel injection direction (10). Turbojet engine according to claim 1, wherein the protection means comprise at least one sheet (8d). Turbojet engine according to one of claims 1 or 2, wherein the injection device is in the form of a radial arm (8). Turbojet engine according to claim 3, wherein the protection means (8d) extend over the entire radial height of the arm (8). Turbojet engine according to one of claims 1 to 4, wherein the fuel injection means comprise at least one tube (8b), supplied with fuel and having fuel injection orifices (10). Turbojet engine according to one of claims 1 to 5 wherein, the fuel injection device (8) further comprising a protective screen (8c), placed in the opening of the enclosure, the protective means (8d) are positioned between a wall (8 ') of the enclosure and the protective screen (8c). Turbojet engine according to one of claims 1 to 6, wherein the fuel injection means (8b) are placed between the walls (8 ') forming the branches of the U-shaped section of the enclosure. Turbojet engine according to claims 2 and 7, wherein a sheet (8d) is placed substantially parallel to each of the walls (8 ') of the enclosure forming the branches of its U-section. A turbojet engine according to claim 8, wherein each plate (8d) is attached to the wall at which it is substantially parallel. Turbojet engine according to one of claims 8 or 9 wherein each plate (8d) is attached to the cooling jacket (8a). Turbojet engine according to claims 2 and 7 wherein the sheet (8d) has a U-section, a radial recess (15), in the central part of the wall forming the base of its U-section, which is slid over a part ( 14) forming a slide, integral with the cooling jacket (8a). Turbojet engine according to claim 2 and one of claims 1 to 11, wherein the sheet (8d) has slots (16). A turbojet engine according to claim 2 and one of claims 1 to 11, wherein the sheet (8d) has a corrugated wall portion. Turbojet engine according to claim 1, wherein the injection device is in the form of a ring. Fuel injection device for a turbojet according to one of Claims 1 to 14. Protective plate for a fuel injection device for a turbojet according to claim 2 and one of claims 1 to 14.

Images