Turbomachine combustion chamber provided with air deflection means for reducing the wake created by an ignition plug

Abstract

A device for cooling of an annular wall of a turbomachine combustion chamber provided with micro-perforations, and in particular the cooling of a region of the wall facing a wake induced by an ignition plug, the device includes, a deflector designed to divert air immersing the ignition plug towards a median plane of the wake and towards the annular wall of the combustion chamber, so as to increase the air pressure within the wake in proximity to the annular wall.

Claims

1. A combustion chamber module for a turbomachine, comprising: an annular enclosure, an annular combustion chamber accommodated in said annular enclosure and including at least one annular wall delimiting said annular combustion chamber and including a plug port as well as a plurality of micro-perforations to let in cooling air in said annular combustion chamber for cooling said at least one annular wall, and an ignition plug extending in said annular enclosure and through said plug port, said combustion chamber module configured to receive an airflow coming from a turbomachine compressor and generally flowing from upstream to downstream of the annular combustion chamber within said annular enclosure, and a portion of the airflow which is designed to bypass the annular combustion chamber by running along said at least one annular wall thereof and by immersing said ignition plug which thus creates a wake, wherein said combustion chamber module further comprises deflection means extending from upstream to downstream by approaching a median plane of said wake, so as to divert, towards said median plane of said wake, the portion of the airflow immersing said ignition plug, and wherein said deflection means comprise two ducts each delimited by a first tangential wall arranged facing the at least one annular wall of the annular combustion chamber, a second tangential wall arranged on an opposite side with respect to the at least one annular wall of the annular combustion chamber, a first sidewall arranged on a side of the ignition plug, and a second sidewall arranged on an opposite side with respect to the ignition plug; wherein each of said two ducts has at least one air inlet to draw air to be diverted as well as at least one air outlet to diffuse the diverted air towards said median plane of said wake; wherein said respective second sidewalls of said two ducts form deflecting walls provided on either side of said ignition plug and extending from upstream to downstream by approaching said median plane of said wake; and wherein said respective tangential walls of said ducts extend in the downstream direction by approaching the annular wall of the annular combustion chamber.

2. The combustion chamber module according to claim 1, wherein said two ducts are carried by an annular support extending around said ignition plug.

3. A turbomachine, comprising the combustion chamber module according to claim 1, as well as a compressor opening into said annular enclosure of said combustion chamber module.

4. A method for designing and manufacturing the combustion chamber module according to claim 1 for an aircraft turbomachine comprising a compressor intended to deliver an airflow to said combustion chamber module, the method comprising: determining the wake produced by said ignition plug in said portion of the airflow immersing said ignition plug; defining a geometry of said deflection means so that the deflection means extend from upstream to downstream by approaching said median plane of said wake and by approaching said annular wall of the annular combustion chamber; and manufacturing the combustion chamber module.

5. A combustion chamber module for a turbomachine, comprising: an annular enclosure, an annular combustion chamber accommodated in said annular enclosure and including at least one annular wall delimiting said annular combustion chamber and including a plug port as well as a plurality of micro-perforations to let in cooling air in said annular combustion chamber for cooling said annular wall, and an ignition plug extending in said annular enclosure and through said plug port, said combustion chamber module configured to receive an airflow coming from a turbomachine compressor and generally flowing from upstream to downstream of the annular combustion chamber within said annular enclosure, and a portion of the airflow which is designed to bypass the annular combustion chamber by running along said at least one annular annular wall thereof and by immersing said ignition plug which thus creates a wake, wherein said annular combustion chamber module further comprises deflection means extending from upstream to downstream by approaching a median plane of said wake, so as to divert, towards said median plane of said wake, the portion of the airflow immersing said ignition plug, and wherein said deflection means comprise a curved duct extending around a portion of said plug port and having an air inlet to draw air to be diverted, and at least one air outlet formed in a median part of a wall delimiting said curved duct and opening into said wake.

6. The combustion chamber module according to claim 5, wherein said curved duct is fitted in a bushing mounted in said plug port and intended to guide said ignition plug.

7. A turbomachine, comprising the combustion chamber module according to claim 5, as well as a compressor opening into said annular enclosure of said combustion chamber module.

8. A method for designing and manufacturing the combustion chamber module according to claim 5 for an aircraft turbomachine comprising a compressor intended to deliver an airflow to said combustion chamber module, the method comprising: determining the wake produced by said ignition plug in said portion of the airflow immersing said ignition plug; defining a geometry of said deflection means so that the deflection means extend from upstream to downstream by approaching said median plane of said wake and by approaching said annular wall of the annular combustion chamber; and manufacturing the combustion chamber module.

9. A combustion chamber module for a turbomachine, comprising: an annular enclosure, an annular combustion chamber accommodated in said annular enclosure and including at least one annular wall delimiting said annular combustion chamber and including a plug port as well as a plurality of micro-perforations to let in cooling air in said annular combustion chamber for cooling said at least one annular wall, and an ignition plug extending in said annular enclosure and through said plug port, said combustion chamber module configured to receive an airflow coming from a turbomachine compressor and generally flowing from upstream to downstream of the annular combustion chamber within said annular enclosure, and a portion of the airflow which is designed to bypass the annular combustion chamber by running along said at least one annular wall thereof and by immersing said ignition plug which thus creates a wake, wherein said combustion chamber module further comprises deflection means extending from upstream to downstream by approaching a median plane of said wake and by approaching said annular wall of the annular combustion chamber, so as to divert, towards said median plane of said wake, the portion of the airflow immersing said ignition plug, wherein the combustion chamber module further comprises a casing surrounding said annular combustion chamber and delimiting said annular enclosure, said deflection means comprising a deflecting wall connected to said casing, said deflecting wall being shaped so that, when seen in cross-section along any plane parallel to said median plane of said wake, said deflecting wall extends in the downstream direction by approaching said annular wall of the annular combustion chamber, and when seen in cross-section along any plane orthogonal to an axis of said ignition plug, said deflecting wall extends in the downstream direction by approaching said median plane of said wake.

10. The combustion chamber module according to claim 9, wherein said deflecting wall is inscribed in a virtual cylinder of revolution having an axis inclined relative to a plane orthogonal to the axis of said ignition plug.

11. A turbomachine, comprising the combustion chamber module according to claim 9, as well as a compressor opening into said annular enclosure of said combustion chamber module.

12. A method for designing and manufacturing the combustion chamber module according to claim 9 for an aircraft turbomachine comprising a compressor intended to deliver an airflow to said combustion chamber module, the method comprising: determining the wake produced by said ignition plug in said portion of the airflow immersing said ignition plug; defining a geometry of said deflection means so that the deflection means extend from upstream to downstream by approaching said median plane of said wake and by approaching said annular wall of the annular combustion chamber; and manufacturing the combustion chamber module.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood, and further detail, features and characteristics thereof will appear upon reading the following description made by way of non-limiting example and with reference to the accompanying drawings in which:

(2) FIG. 1, already described, is an axial cross-section partial schematic view of a known type turbomachine;

(3) FIG. 2, already described, is an axial cross-section partial schematic half-view of an annular combustion chamber of the turbomachine of FIG. 1;

(4) FIG. 3, already described, is a top partial schematic view of a radially outer annular wall of the combustion chamber of FIG. 2;

(5) FIG. 4, already described, is a graph representing the total pressure (on the abscissa) as a function of the circumferential position (on the ordinate) along the transverse segment S of FIG. 3;

(6) FIGS. 5 and 6 are partial schematic perspective views of a combustion chamber module according to a first preferred embodiment of the invention;

(7) FIG. 7 is an axial cross-section partial schematic view of a combustion chamber module according to a second preferred embodiment of the invention;

(8) FIG. 8 is a partial schematic view of the combustion chamber module of FIG. 7, in cross-section along a plane P1;

(9) FIG. 9 is a schematic perspective view of a deflecting wall of the combustion chamber module of FIG. 7.

(10) Throughout these figures, identical references can refer to identical or analogous elements.

DETAILED DISCLOSURE OF PREFERRED EMBODIMENTS

(11) FIGS. 5 and 6 illustrate a combustion chamber module of a turbomachine according to a first embodiment of the invention, and more particularly represent a region of the radially outer annular wall 13 of the combustion chamber, provided with a plug port 46 in which a bushing 48 is mounted.

(12) The combustion chamber module also includes an ignition plug mounted in the bushing 48, but this ignition plug is not represented in FIGS. 5 and 6 for the sake of clarity. The combustion chamber module also includes an annular enclosure delimited by inner and outer casings and in which the combustion chamber is accommodated, similarly to the example of FIG. 2. These elements can also not be seen in FIGS. 5 and 6. These FIGS. 5 and 6 also show primary ports 40 and dilution ports 42, as well as micro-perforations 53, these elements being for example of a conventional type.

(13) In the illustrated example, the turbomachine under consideration includes a compressor designed to deliver an airflow without a gyratory component to the combustion chamber module. Such an airflow thus generally flows along a direction parallel to the axis 14 of the combustion chamber.

(14) In this case, as explained above, the wake 52 induced by the ignition plug and by the associated bushing is substantially centred relative to the median axial plane P of the plug port 46. This latter plane thus forms a median plane of the wake.

(15) According to the invention, the combustion chamber module further includes deflection means to divert a portion 34 of the outer bypass airflow traveling in proximity to the ignition plug towards the median plane P of the wake and of the radially outer annular wall 13 of the combustion chamber, as will appear more clearly hereinafter.

(16) Thus, in the first embodiment illustrated in FIGS. 5 and 6, the deflection means include two ducts 60 each delimited by a first tangential wall 62 arranged facing the annular wall 13 of the combustion chamber, a second tangential wall 64 arranged on the opposite side with respect to the annular wall 13 of the combustion chamber, a first sidewall 66 arranged facing the bushing 48, and a second sidewall 68 arranged on the opposite side with respect to the bushing 48. Both sidewalls 66, 68 are each connected to both tangential walls 62, 64, and the latter are connected to an annular support 70 engaged on the bushing 48 so as to extend around the ignition plug.

(17) The tangential walls 62 and 64 of each duct are shaped so as to extend towards downstream by approaching the annular wall 13 of the combustion chamber, so as to increase the action of the diverted air in the region of the wake 52 located in proximity to the bushing 48.

(18) Each of the ducts 60 has an air inlet 72 facing upstream, as well as a first air outlet 74 facing downstream and towards the median plane P of the wake. In the illustrated example, each duct is continued beyond the first air outlet 74 by a duct extension 75 having a second air outlet 76.

(19) The second sidewall 68 of each of the ducts 60 extends towards downstream by approaching the median plane P of the wake, and thus forms a deflecting wall able to divert the air entering the duct towards said median plane P.

(20) In the illustrated example, the second sidewall 68 of each of the ducts 60 extends parallel to the axis of the ignition plug, which coincides with the axis 47 of the plug port 46. The second sidewall 68 is thus substantially orthogonal to the annular wall 13 of the combustion chamber.

(21) Each duct extension 75 is delimited by an extension of each of the tangential walls 62 and 64, and by a first extension sidewall 78 provided on the side of the median plane P of the wake and a second extension sidewall 80 provided on the opposite side. The latter wall extends towards downstream by approaching the median plane P of the wake, with a higher approaching rate than the one of the corresponding second sidewall 68. This second extension sidewall 80 thus also forms a deflecting wall, according to the terminology of the invention.

(22) Moreover, in the illustrated example, both ducts 60 are symmetrically arranged relative to the median plane P of the wake.

(23) In operation, part of the air supplied to the combustion chamber module by the compressor of the turbomachine travels in the outer bypass space 38 along the radially outer annular wall 13 of the combustion chamber. A portion 34 of the outer bypass airflow, passing in proximity to the ignition plug and the associated bushing 48, enters the ducts 60 and is guided by the second sidewalls 68 and by the second extension sidewalls 80. The ducts 60 thus deliver through their outlets 74 and 76 an airflow 82 diverted towards the median plane P of the wake and the outer annular wall 13 of the combustion chamber. As a result, the total pressure of air is increased in the corresponding area of the wake 52 in proximity to the annular wall 13, enabling the convective exchanges to be improved through the micro-perforations 53, and thus the cooling of the annular wall 13 to be improved.

(24) In a second preferred embodiment of the invention illustrated in FIGS. 7 to 9, the deflection means include a deflecting wall 90 connected to the outer casing 16 (FIGS. 7 and 2) surrounding the combustion chamber 8 and delimiting the annular enclosure in which this combustion chamber is accommodated.

(25) This deflecting wall 90 is shaped so that, when seen in cross-section along any plane parallel to the median plane P of the wake, the deflecting wall 90 extends towards downstream by approaching the annular wall 13 of the combustion chamber, and so that, when seen in cross-section along any plane orthogonal to the axis of the ignition plug which coincides with the axis 47 of the plug port 46, the deflecting wall 90 extends towards downstream by approaching the median plane P of the wake.

(26) For this purpose, in the illustrated example, the deflecting wall 90 is inscribed in a virtual cylinder of revolution 92, as illustrated in FIG. 9. More precisely, the deflecting wall 90 corresponds to a section of the cylinder 92 delimited by two planes P1 and P2 which intersect along a line D orthogonal to the axis 94 of the cylinder 92. The plane P1 delimits an upper rim of the deflecting wall 90, through which the latter is connected to the outer casing 16. The plane P1 is thus tangent to this casing 16, and is for example orthogonal to the axis 47 of the plug port 46. The plane P2 delimits a lower rim of the deflecting wall 90. Both planes P1 and P2 have an angle ? therebetween, for example equal to about 30 degrees. Moreover, the axis 94 of the virtual cylinder 92 is for example at an angle ? equal to about 45 degrees with the axis 47 of the plug port 46. The axis 94 of the cylinder is thus tilted relative to the plane P1.

(27) By way of example, as shown in FIG. 7, the outer casing 16 includes a boss 95 provided with a port through which the ignition plug 50 extends. The deflecting wall 90 is then advantageously fixed on this boss 95.

(28) FIG. 7 also shows a more detailed example bushing 48 intended to guide the ignition plug 50. This bushing 48 includes a plug guide 96 mounted on a chimney 98 and retained on the latter by an annular piece 100 sometimes referred to as a cup, as well as a ring 102 crimped in the plug port 46 and in which the chimney 98 is crimped. In a manner known per se, the plug guide 96 thus has a freedom of movement perpendicularly to the axis 47 of the plug port 46, which enables the bushing 48 to support the deformations of the combustion chamber module induced by the usual phenomena of differential expansions.

(29) In operation, as illustrated in FIGS. 7 and 8, part of the air supplied to the combustion chamber module by the compressor of the turbomachine travels in the outer bypass space 38 along the radially outer annular wall 13 of the combustion chamber. A portion 34 of the outer bypass airflow, passing in proximity to the ignition plug, travels towards the deflecting wall 90 and is diverted by the latter so as to constitute an airflow 104 diverted towards the median plane P of the wake and towards the annular wall 13 of the combustion chamber.

(30) As a result, the total pressure of air is again increased in the area corresponding to the wake, enabling the convective exchanges to be improved through micro-perforations of the annular wall 13.

(31) In the illustrated example, the deflecting wall 90 further makes it possible to conceal a region of the outer casing 16 located downstream of the boss 95 of the latter, and thus makes it possible to reduce the level of heat transfer by convection between air and the outer casing 16 at this area. As a result, the heat constraints applied to this particularly exposed area of the outer casing 16 are reduced, and therefore the lifetime of this casing is improved.

(32) Generally speaking, the invention thus makes it possible to improve the lifetime of the annular wall 13 of the combustion chamber in the region of the wake 52 and to reduce the risks of loosening of elements forming the bushing 48 intended to guide the ignition plug through the annular wall 13.

(33) The invention can further make it possible to improve the lifetime of the outer casing 16 when the latter has a boss 95 such as above-described.

(34) In the examples above-described with reference to the accompanying figures, the compressor of the turbomachine is of the type delivering an airflow 26 without a gyratory component, so that the median plane P of the wake is a plane passing through the axis 14 of the combustion chamber.

(35) Of course, the invention also applies to turbomachines including a compressor which is designed to deliver an airflow according to a gyratory movement. In this case, the median plane P of the wake is tilted relative to the axis 14 of the combustion chamber, and the orientation of the deflecting means according to the invention can be adapted accordingly.