Other characteristics and advantages of the present invention appear from the following description made with reference to the accompanying drawings that show an embodiment without any limiting character.
In the figures:
In a manner that is itself well known, such a combustion chamber 2 is made up of an inner longitudinal annular wall and an outer longitudinal wall (these walls not being shown in
The chamber end wall 4 presents an upstream side 4a and a downstream side 4b, the downstream side facing towards the inside of the combustion chamber 2. The chamber end wall is pierced by a plurality of openings 6 that are regularly spaced apart, each being substantially circular in shape about an axis X-X. An injector system 8 for injecting an air/fuel mixture is associated with each of these openings 6.
A deflector 10 protecting the chamber end wall 4 from combustion flames is also mounted in each of the openings 6 on the downstream side 4b of the chamber end wall via an annulus 12 projecting from the upstream side.
In accordance with the invention, the deflector 10 presents an annular collar 14 that extends radially inwards (i.e. towards the axis X-X of the opening 6 in the chamber end wall). As explained below, the collar 14 of the deflector serves to protect the injector system against combustion flames.
Each injector system 8 possesses an axis of symmetry Y-Y and comprises in particular a fuel injector secured to the casing of the turbomachine (not shown in the figures). The head 16 of the injector disposed on the upstream side 4a of the chamber end wall 4 and it is centered on the axis Y-Y of the injector system via a centering ring 18 that surrounds it.
One or more air swirlers 20, possibly including venturies 22, are fastened to the downstream end of the centering ring 18 of the injector system. This or these air swirlers 20 enable air to penetrate into the injector system along a direction that is substantially radial and to mix with the fuel delivered by the head 16 of the fuel injector. The air/fuel mixture then penetrates into the combustion chamber 2 where it is ignited.
Each injector system 8 also has a “pinch” ring 24 that is mounted on the upstream side 4a of the chamber end wall 4 and that is fastened against the annulus 12 for holding the deflector 10. The pinch ring 24 is centered on the axis X-X of the opening 6 in the chamber end wall and co-operates with the annulus 12 to define an annular groove 26 that is open towards the axis X-X.
Each injector system 8 also has a bowl 28 fastened against the downstream end of the air swirler 20 and serving to provide good distribution of the air/fuel mixture in the primary zone of the combustion area.
The bowl 28 is mounted in the corresponding opening 6 of the chamber end wall 4 and passes therethrough. It is generally in the form of a ring centered on the axis Y-Y of the injector system and it terminates at its downstream end with a channel section annular groove 30 that is outwardly open (i.e. open away from the axis X-X of the opening in the chamber end wall), and that is in radial alignment with the collar 14 of the deflector 10.
At its upstream end, the bowl 28 has an annular end plate 32 mounted on the upstream side 4a of the chamber end wall 4 and suitable for sliding radially inside the groove 26 formed between the pinch ring 24 and the annulus 12 for holding the deflector 10, thus enabling the injector system 8 to shift off-center relative to the chamber end wall 4.
Thus, the head 16 of the fuel injector and the injector system assembly 8 are mounted to slide relative to the chamber end wall so as to accommodate thermal expansion differences between the casing and the combustion chamber. With this type of arrangement, the head 16 of the fuel injector thus remains continuously centered relative to the injector system 8.
The end plate 32 of the bowl is extended downstream by a substantially cylindrical portion 34 of diameter that is smaller than the diameter of the opening 6, and it is connected to the groove 30 by an annular shoulder 36 on the upstream side thereof. The groove 30 is disposed behind an annular flange 38 that projects radially outwards and that is of a diameter that is smaller than the diameter of the shoulder 36.
The groove 30 of the bowl is formed by two annular side walls 42, 44 that are axially spaced apart and that are interconnected at their inside ends by an annular bottom wall 40, one of the side walls 42 being connected at its outer end to the shoulder 36, and the other side wall 44 being connected at its outer end to the flange 38.
The flange 38 is the portion of the bowl that is situated furthest downstream. The flange is extended upstream by a portion 46 that flares downstream, this flared portion 46 itself being extended upstream by a cylindrical portion 48 that is concentric with the cylindrical portion 34 of the bowl (and of smaller diameter) and is connected to the air swirler 20. The flared portion 46 of the bowl is pierced by a plurality of air introduction holes 50.
The shoulder 36 of the bowl is also pierced by a plurality of ventilation holes 52 open on the upstream side of the chamber end wall 4 and leading to its downstream side in register with the collar 14 of the deflector 10. The air flowing through the ventilation holes 52 cools the collar 14 of the deflector from the upstream side and then flows into the groove 30 of the bowl so as to create a film of air that then flows radially along the downstream side of the deflector 10 in order to cool it.
The operation of such an arrangement is described below, in particular in the event of the injector system 8 becoming off-center relative to the chamber end wall 4.
In
According to an advantageous characteristic of the invention, the distance between the side walls 42, 44 of the bowl groove 30 is greater than the thickness of the collar 14 of the deflector 10 so as to allow ventilation air passing through the holes 52 pierced in the shoulder 36 to flow regardless of the off-centering of the injector system relative to the chamber end wall. Thus, in the extreme off-centered configuration of
The arrangement of the invention is mounted as flows. The deflector-holding annulus 12, the bowl 28, the pinch ring 24, the air swirler 20, and the centering ring 18 are mounted from the upstream side (i.e. from the side 4a of the chamber end wall 4), and they are fastened to one another (e.g. by brazing or by welding). The deflector 10 is mounted in the opening 6 in the chamber end wall 4 from the downstream side (i.e. from the side 4b of the chamber end wall) and is then fastened to the annulus 12.
It can thus be understood that even in the event of the brazing or welding making the connection between the various component parts of the injector system, none of the parts can fall into the combustion chamber 2.
It can also be understood that given that the deflector 10 is mounted from the downstream side, the collar 14 thereof can present a diameter smaller than the diameter of the opening 6 in the chamber end wall 4, which is selected as a function of the maximum possible off-centering differences of the injector system relative to the chamber end wall so as to ensure continuous thermal protection for the injector system against the combustion flames.
Number | Date | Country | Kind |
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0652718 | Jun 2006 | FR | national |