STATOR OF AN AIRCRAFT TURBINE ENGINE

Abstract

A stator of an aircraft turbine engine, comprising an annular row of fixed vanes and an annular row of arms, wherein the trailing edges of the fixed vanes are positioned substantially in a first transverse plane that is positioned downstream of a second transverse plane that passes substantially through the leading edges of the arms.

Claims

1. A stator of an aircraft turbine engine, comprising an annular row of fixed vanes having leading edges and trailing edges and an annular row of arms having leading edges and trailing edges, the stator having an axis of revolution, wherein: the trailing edges of the fixed vanes are positioned substantially in a first plane that is transverse to said axis of revolution and is positioned downstream of a second plane that is transverse to said axis of revolution and passes substantially through the leading edges of the arms, and the leading edges of the fixed vanes are positioned substantially in a third plane that is transverse to said axis of revolution and is positioned upstream of the second plane, and wherein the stator further comprises an annular row of variable-pitch vanes that is positioned directly downstream of the annular row of arms, the annular row of variable-pitch vanes comprising first variable-pitch vanes that are positioned substantially along an extension of a chord of the arms, and second variable-pitch vanes that are each positioned between a corresponding two of the first variable-pitch vanes, the first variable-pitch vanes having different aerodynamic profiles than the second variable-pitch vanes.

2. The stator according to claim 1, wherein the arms are inclined relative to the axis of revolution of the stator.

3. The stator according to claim 2, wherein the arms and the fixed vanes are substantially parallel.

4. The stator according to claim 1, further comprising two annular walls that are inner wall and outer wall, respectively, between which the rows of fixed vanes and arms extend.

5. The stator according to claim 4, wherein each variable-pitch vane comprises, at its outer radial end, a cylindrical pivot that is mounted in a duct on the outer wall.

6. The stator according to claim 4, wherein the outer wall comprises: upstream of the arms, an annular row of discharge air through-slots and means for closing said slots, or between the arms, at least one discharge air through-opening and at least one door for closing said through-opening.

7. The stator according to claim 1, wherein the first variable-pitch vanes have aerodynamic profiles or curvatures that are more accentuated than those of the second variable-pitch vanes.

8. An aircraft turbine engine comprising at least one stator according to claim 1.

Description

DESCRIPTION OF THE FIGURES

[0030] The invention will be better understood, and other details, features and advantages of the invention will become apparent upon reading the following description, given by way of non-limiting example and with reference to the accompanying drawings, in which:

[0031] FIG. 1 is a schematic, axial sectional half view of an aircraft turbine engine according to the prior art, viewed from the side,

[0032] FIG. 2 is a highly schematic plan view of a part of the turbine engine from FIG. 1,

[0033] FIG. 3 is a schematic, axial sectional half view of an aircraft turbine engine according to the invention, viewed from the side,

[0034] FIG. 4 is a highly schematic plan view of a part of the turbine engine from FIG. 3,

[0035] FIG. 5 is a view corresponding to FIG. 3 that shows an embodiment of an inlet casing according to the invention, and

[0036] FIGS. 6 and 7 are views corresponding to FIG. 3 that show variants of an intermediate casing according to the invention.

DETAILED DESCRIPTION

[0037] Reference is first made to FIG. 1, which shows a turbine engine 10 according to the prior art, said turbine engine 10 in this case being a bypass turbojet engine. The invention is described with reference to this example, but it is clear that the invention is applicable to other turbine engine architectures.

[0038] The turbine engine 10 comprises, from upstream to downstream, in the direction of flow of the gases, a fan 12 which generates a flow which divides into two coaxial flows, the primary flow powering the engine which comprises a low-pressure compressor 14, a high-pressure compressor (not shown), a combustion chamber (not shown), high-pressure and low-pressure turbines (not shown) and a pipe (not shown) for ejecting combustion gases.

[0039] These modules of the engine (fan, compressors, combustion chamber, turbines) are surrounded by structural annular stator casings. The turbine engine 10 thus comprises a plurality of successive annular casings, including an inlet casing 18 upstream of the low-pressure compressor 14, and an intermediate casing 20 between the low-pressure and high-pressure compressors.

[0040] The inlet casing 18 comprises an annular row of structural arms 24 (or primary arms) which is inserted between an annular row of fixed vanes 22 (or inlet guide vanes (IGV)) and an annular row of variable-pitch vanes 26 (or variable stator vanes (VSV)).

[0041] As can also be seen in FIG. 2, the row of fixed vanes 22 is positioned between the fan 12 and the row of arms 24, and the row of variable-pitch vanes 26 is positioned between the row of arms 24 and a movable rotor wheel 28 of the low-pressure compressor 14.

[0042] In the same way, the intermediate casing 20 comprises an annular row of structural arms (or primary arms) which is inserted between an annular row of fixed vanes (or inlet guide vanes (IGV)) and an annular row of variable-pitch vanes (or variable stator vanes (VSV)). The row of fixed vanes is positioned between a rotor wheel of the low-pressure compressor and the row of arms, and the row of variable-pitch vanes is positioned between the row of arms and a rotor wheel of the high-pressure compressor.

[0043] Reference numeral 34 in FIG. 2 represents the speed triangles of the air flow entering the fan 12, and reference numerals 36 and 38 represent the speed triangles of the primary air flow upstream of the fixed vanes 22 and downstream of the variable-pitch vanes 26.

[0044] As explained above, the inlet casing 18 and the intermediate casing 20 each form, axially together with the rows of vanes 22, 26, a bulky stator.

[0045] The invention makes it possible to overcome this problem by axially interlinking the row of fixed vanes with the row of arms of the stator.

[0046] FIGS. 3 and 4 show an embodiment of a stator or inlet casing according to the invention, this embodiment of course also being applicable to an intermediate casing.

[0047] P1 denotes a transverse plane (perpendicular to the longitudinal axis A or axis of revolution of the stator 40 and of the turbine engine) passing substantially through the trailing edges 42 of the fixed vanes 44, P2 denotes a transverse plane passing substantially through the leading edges 46 of the arms 48, P3 denotes a transverse plane passing substantially through the leading edges 50 of the fixed vanes 44, P4 denotes a transverse plane passing substantially through the trailing edges 52 of the arms 48, and P5 denotes a transverse plane passing substantially through the leading edges 54 of the variable-pitch vanes 56, 58.

[0048] In the example shown, P1 is downstream of P2 which is downstream of P3. Moreover, P5 is downstream of P4 and at a short axial distance therefrom. The variable-pitch vanes 56, 58 are therefore positioned directly downstream of the arms 48.

[0049] In addition, H1 denotes a central longitudinal plane for each arm 48 and H2 denotes a central longitudinal plane for each fixed vane 44.

[0050] In this case, the planes H1 and H2 are inclined relative to the axis A and are substantially mutually parallel. In comparison with the prior art, the arms 48 therefore do not have an axial orientation, but are by contrast “provided with a pitch” (at an angle of 20-30°, for example) around an axis that is substantially radial relative to the axis A.

[0051] Each arm 48 is symmetrical to its plane H1. Each arm 48 is tubular in order to allow auxiliary systems to pass therethrough, and in addition it may be structural or non-structural. Each arm 48 preferably retains its dimensions, such as its chord and its thickness, in comparison with the prior art shown in FIGS. 1 and 2.

[0052] The fixed vanes 44 may be similar to those from the prior art.

[0053] The annular row of variable-pitch vanes 56, 58 comprises first vanes 56 that are in the extension of the arms 48 and second vanes 58 that are positioned between the first vanes 56 and downstream of the fixed vanes 44 in relation to the flow.

[0054] As schematically shown in the drawings, the profiles of the vanes 56 are more accentuated than those of the vanes 58. The portion of the air flow that flows through the fixed vanes 44 is deflected to a greater extent than the portion of the air flow flowing along the arms 48 due to the curvature of the profile of the fixed vanes 44. So that the air flow leaving the stator is homogenous over its entire circumference, it is necessary for the portion of the air flow flowing from the trailing edges of the arms 48 to be deflected to a greater extent than that flowing from the trailing edges of the fixed vanes 44. The profiles of the vanes 56, 58 are therefore configured so that the portion of the air flow flowing from the trailing edges of the arms 48 is deflected to a greater extent than that flowing from the trailing edges of the fixed vanes 44, and so that the air flow leaving the stator is homogenous over its entire circumference. This air flow advantageously has a speed triangle 38 that is substantially identical to that from the prior art (FIG. 2), such that the air flow over the rotor wheel 28 positioned downstream is not impacted by the configuration of the stator/inlet casing according to the invention.

[0055] Reference is now made to FIG. 5, which shows a more specific embodiment of a stator 40 according to the invention, which in this case is an inlet casing 18.

[0056] As in the above-mentioned example, the stator 40 comprises rows of fixed vanes 44, rows of arms 48 and rows of variable-pitch vanes 56, 58, said variable-pitch vanes having two different profiles. These rows of vanes 44, 56, 58 and rows of arms 48 extend between two coaxial annular walls, which are inner 62 and outer 64, respectively.

[0057] Each variable-pitch vane 56, 58 comprises, at its outer radial end, a cylindrical pivot 66 that is mounted in a duct 68 on the outer wall 64 and is connected to a control ring (not shown) by a connecting rod 69 in order to position the vane 56, 58 about the axis defined by its pivot 66.

[0058] Reference is now made to FIGS. 6 and 7, which show variants of stators 40′, 40″ according to the invention, which are intermediate casings 20 in this case.

[0059] As in the above-mentioned example, each stator 40′, 40″ comprises rows of fixed vanes 44, rows of arms 48 and rows of variable-pitch vanes 56, 58 having two different profiles. These rows of vanes 44, 56, 58 and rows of arms 48 extend between two coaxial annular walls, which are inner 62 and outer 64, respectively. Each variable-pitch vane 56, 58 comprises, at its outer radial end, a cylindrical pivot 66 that is mounted in a duct 68 on the outer wall 64 and is connected to a control ring (not shown) by a connecting rod 69 in order to position the vane 56, 58 about the axis defined by its pivot 66.

[0060] In addition, the outer wall 64 further comprises means for discharging air. For FIG. 6, the outer wall 64 comprises, upstream of the arms 48, an annular row of discharge air through-slots 70 and means 72 for closing said slots 70. For FIG. 7, the outer wall 64 comprises, between the arms 48, at least one air through-opening 80 and at least one door 82 for closing said opening 80, the door 82 in this case being mounted so as to pivot about an articulation shaft 84. This articulation shaft 84 is positioned at an upstream end of the door 82 and is, for example, substantially tangential to a circumference centred on the longitudinal axis of the stator 40″.

[0061] Preferably, the stator 40, 40′, 40″ according to the invention is integrally formed, i.e. formed in one piece, of course with the exception of the variable-pitch vanes, which have to remain movable. The stator can be produced in a plurality of steps, for example from a blank casting that is machined and then machine-welded.