TURBOMACHINE CENTRE BLADE COMPRISING A CURVED PORTION

Abstract

A turbomachine compressor blade of main radial orientation with respect to a main axis of the turbomachine. The blade includes a radially internal root portion, a radially external tip portion, a radially intermediate portion, a curved portion tangentially in a direction, and at least one straight portion on the root portion and/or on the tip portion.

Description

TECHNICAL FIELD

The invention relates to a turbomachine blade which is implemented in such a way as to limit the coincidences of vibrational frequencies of the blade in relation to the frequencies of solicitation of the blade during the operation of the turbomachine, which would risk resulting in a deterioration of the blade or even breakage of it.

PRIOR ART

During the operation of a turbomachine, the flow of gas along stator blades causes the blades to vibrate.

Each blade has one or several natural frequencies for which the amplitude of the vibration can become excessive and cause the deterioration or breakage of the blade.

U.S. Pat. No. 3,745,629 describes a turbomachine blade which is curved according to a profile which is similar to the profile of a blade in vibration in one of its natural frequencies.

This curvature makes it possible to limit the vibrations of the blade in a range of frequencies that correspond to the operating conditions of the turbomachine, and as such limit the risks of breakage of the blade.

However, such a curvature also reduces the effectiveness and the aerodynamic performance of the blade.

The invention has for purpose to propose a turbomachine blade which is carried out in such a way that the natural frequency or frequencies are different from the frequencies of solicitation of the blade during the operation of the turbomachine.

DESCRIPTION OF THE INVENTION

The invention proposes a turbomachine compressor blade of radial main orientation with respect to the main axis of the turbomachine, with the blade comprising a radially internal root portion, a radially external tip portion and a radially intermediate portion,

characterised in that the blade comprises a curved portion in tangentially direction and at least one straight portion on the root portion and/or on the tip portion.

Such a tangentially curved portion modifies the vibrational response of the blade to the vibrational solicitations, and removes the frequencies at risk outside of the operating range of the blade.

More preferably, the radial length L1 of the curved portion is between 30% and 60% of the radial length L of the blade.

More preferably, the tangential amplitude A of the curved portion is between 1% and 5% of the radial length L of the blade.

More preferably, said straight portion is inclined by an angle less than or equal to 30° with respect to the main radial direction of the blade.

More preferably, the curved portion is positioned radially on the root portion.

More preferably, the curved portion is positioned radially on the tip portion.

More preferably, the curved portion is positioned radially on the median portion.

More preferably, the curved portion is tangentially curved in the direction of the intrados of the blade.

The invention also proposes a turbomachine compressor stator comprising radial blades distributed around the main axis of the turbomachine, characterised in that each blade is carried out such as defined hereinabove.

The invention also proposes a turbomachine comprising a stator that comprises blades such as defined hereinabove.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention shall appear when reading the following detailed description for the understanding of which reference will be made to the annexed figures along which:

FIG. 1 is a diagrammatical drawing in perspective of a blade comprising a curved portion according to the invention;

FIG. 2 shows the tangential stacking law of the centre of gravity of the sections of a blade according to the invention.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

In the following description, identical, similar or analogous elements shall be designated by the same reference numbers.

For the description of the invention, in a non-limiting manner the radial, tangential and axial orientations shall be adopted according to the marking R, T, A shown in FIG. 1, wherein the radial orientation is the main orientation of the blade and the tangential orientation is the orientation perpendicular to a main axial plane of the blade.

FIG. 1 shows a blade 10 that is part of a stator (not shown) of the compressor of a turbomachine.

The compressor comprises a plurality of blades 10 which are evenly distributed around the main axis of the turbomachine, in order to form an annular set, called a rectifier grid, through which a flow of gas, here air, passes.

The blade 10 extends globally radially according to the orientation R with respect to the main axis of the turbomachine.

The blade 10 comprises a radially internal portion 12, called the root of the blade, on which the blade 10 is fixed to an inner ferrule of the compressor (not shown).

The blade 10 comprises a radially external portion 14 called the tip of the blade, on which the blade 10 is fixed to an outer ferrule of the compressor (not shown).

The blade 10 comprises an intermediate portion 16 that connects the root 12 to the tip 14 of the blade 10.

The inner ferrule and the outer ferrule of the compressor delimit an annular duct called a stream, wherein the flow of air flows and interacts with the blade 10.

The blade 10 further comprises a leading edge 18, which is located axially upstream according to the direction of the gas flow with respect to the blade 10, and a trailing edge 20 that is located axially downstream according to the direction of the gas with respect to the blade 10.

The blade 10 is furthermore cambered and comprises a face 22 called intrados, that is located on the side opposite the camber and a face 24 called extrados that is located on the side of the camber.

FIG. 2 shows a curve 26 showing the tangential stacking law of the centre of gravity of the sections of the blade 10.

This tangential stacking law corresponds to the position of the centre of gravity of each section of the blade according to a plane perpendicular to the main radial direction of the blade, with respect to the main radial axis of the blade 10.

This curve 26 comprises a root portion 28 corresponding to the root 12 of the blade 10, a tip portion 30 corresponding to the tip 14 of the blade 10 and an intermediate portion 32 corresponding to the intermediate portion of the blade 10.

According to the invention, the blade 10 is carried out in such a way that it comprises a portion 34 that is curved tangentially and at least one straight portion.

As such, as can be seen in more detail in FIG. 2, the curve 26 comprises a tangentially curved portion 36 corresponding to the curbed portion 34. The curve 26 further comprises at least one curved portion corresponding to the straight portion of the blade 10.

According to the invention, the straight portion of the blade 10 is located on the root 12 and/or on the tip 14 of the blade 10, according to the position of the curved portion 34.

As such, the straight portion of the curve 26 is located on the root portion 28 and/or on the tip portion 30, according to the radial position of the curved portion 36.

According to a first aspect of the invention, the curved portion 34 is located radially on the root 12 of the blade 10. The straight portion is then located on the tip 14 of the blade 10. Consequently, the curved portion 36 is located radially on the root portion 28 and tip portion 30 of the curve 26 is straight.

According to a second aspect of the invention, the curved portion 34 is located radially on the tip 14 of the blade 10. The straight portion is then located on the root 12 of the blade 10. The curved portion 36 of the curve 26 is consequently located radially on the tip portion 30 and the root portion 28 of the curve 26 is straight.

According to a third aspect of the invention, the curved portion 34 is located radially on the intermediate portion 16 of the blade 10. The root 12 and the tip 14 of the blade 10 each form a straight portion of the blade 10.

Consequently, the curved portion 36 is located radially on the intermediate portion 32 and the root portion 28 and the tip portion 30 of the curve 26 are both straight.

Furthermore, according to a preferred embodiment, the blade 10 is curved in such a way that the curved portion 34 is tangentially curved in the direction of the intrados 22, as shown in FIG. 1.

According to an alternative embodiment not shown, the curved portion 34 is curved in the direction of the extrados 24.

The dimensions of the curved portion 36 are defined with respect to the radial length “L” of the blade 10.

As such, the radial dimension “L1” of the curved portion 36 is between 30% and 60% of the radial dimension “L” of the blade 10.

As such, the tangential dimension “A” of the curved portion 36 is between 1% and 5% of the radial dimension “L” of the blade 10.

As was mentioned hereinabove, according to the radial position of the curved portion, the root portion 28 and/or the tip portion 30 is straight.

In this case, each tip portion 28 and/or root portion 30 that is straight, is inclined with respect to the main radial direction of the blade by an angle of which the value is less than or equal to 30°.

Claims

1-10. (canceled)

11. A turbomachine compressor blade of main radial orientation with respect to a main axis of the turbomachine, the blade comprising: a radially internal root portion;a radially external tip portion;a radially intermediate portion;a curved portion perpendicularly to a main axial plane of the blade in a direction; andat least one straight portion on the root portion and/or on the tip portion.

12. A blade as claimed in claim 11, wherein a radial length of the curved portion is between 30% and 60% of a radial length of the blade.

13. A blade as claimed in claim 11, wherein a tangential amplitude of the curved portion is between 1% and 5% of a radial length of the blade.

14. A blade as claimed in claim 11, wherein the straight portion is inclined by an angle less than or equal to 30° with respect to a main radial direction of the blade.

15. A blade as claimed in claim 11, wherein the curved portion is positioned radially on the root portion.

16. A blade according to 11, wherein the curved portion is positioned radially on the tip portion.

17. A blade according to claim 11, wherein the curved portion is positioned radially on the intermediate portion.

18. A blade as claimed in claim 11, wherein the curved portion is tangentially curved in a direction of intrados of the blade.

19. A turbomachine compressor stator comprising: radial blades distributed around the main axis of the turbomachine,wherein each blade is a blade as claimed in claim 11.

20. A turbomachine comprising a stator that comprises blades as claimed in claim 19.