Turbine rotor disk blade having a foot of curvilinear shape

Abstract

A rotor blade for a rotor disk of a turbine of an aeronautical turbomachine includes, in a radial direction from inside to outside, a blade foot root, a support, a platform and a rotor vane, where the root is connected to the support by a neck. The neck has a curvilinear profile defining, in a section in a plane perpendicular to the radial direction, a curved shape. The neck section overlaps at least 75% of the section of the rotor vane, as a projection of the sections of the neck and of the rotor vane in a plane perpendicular to the radial direction, where the section of the rotor vane joins with the platform.

Claims

1. A rotor blade for a rotor disk of a turbine of a turbomachine comprising, in a radial direction from inside to outside: a blade foot root; a support; a platform; and a rotor vane, wherein the root is connected to the support by a neck, wherein the neck has a curvilinear profile defining, in a section in a plane perpendicular to the radial direction, a dished shape, wherein a section of the neck overlaps at least 75% of a section of the rotor vane, as a projection of the sections of the neck and of the rotor vane in a plane perpendicular to the radial direction, in an area where the section of the rotor vane joins the platform, and wherein, in the projection of the sections of the neck and of the rotor vane in the plane perpendicular to the radial direction in the area where the section of the rotor vane joins the platform, a leading edge of the rotor vane is further upstream than an upstream end of the neck in an axial direction and a trailing edge of the rotor vane is further downstream of a downstream end of the neck in the axial direction.

2. The rotor blade according to claim 1, wherein the foot of the rotor blade, including the root, the neck and the support, has a curvilinear profile defining, as the section in the plane perpendicular to the radial direction, a curved shape.

3. The rotor blade according to claim 1, wherein the neck and the rotor vane have a curved shape, with a same alignment.

4. The rotor blade according to claim 1, wherein the curvilinear profile of the neck defines, in the section in the plane perpendicular to the radial direction, a parallelogram shape which is curved in a curvilinear axis.

5. The rotor blade according to claim 4, wherein the curvilinear axis includes a first portion configured to extend parallel to a rotational axis of the turbine rotor blade, defining an angle which is zero between the first portion of the curvilinear axis and the rotational axis, where the first portion of the curvilinear axis is configured to be located in an upstream part of the neck.

6. The rotor blade according to claim 5, wherein the curvilinear axis includes a second portion configured to extend at a non-zero angle of less than or equal to 45 relative to the rotational axis of the turbine rotor blade.

7. The rotor blade according to claim 6, wherein the second portion of the curvilinear axis is configured to be located downstream from the first portion of the curvilinear axis.

8. A rotor disk for a turbomachine, comprising: a turbine disk; and a plurality of rotor blades according to claim 1, supported by the turbine disk and distributed circumferentially around the turbine disk.

9. A turbine for a turbomachine, including at least one rotor disk according to claim 8.

10. A turbomachine, including a turbine according to claim 9.

11. The rotor blade according to claim 1, further comprising a tip at a radially outer end of the rotor vane, the tip including a wiper.

Description

BRIEF DESCRIPTION OF THE ILLUSTRATIONS

(1) The invention will be able to be better understood on reading the detailed description, below, of a non-restrictive example implementation of it, and also on examining the figures, which are schematic and partial, of the appended illustration, in which:

(2) FIG. 1 is a diagrammatic axial section view of an example of a turbofan suitable for implementation of the invention,

(3) FIG. 2 gives a perspective view of an example of a turbine disk of the turbofan of FIG. 1,

(4) FIGS. 3A and 3B illustrate, as partial section views, example shapes of supports of turbine disk blade foots, respectively a progressive support and a straight support,

(5) FIG. 4 partially illustrates, seen from a top view, the overlap of the section in the foot of the rotor vane by the neck of the foot for a turbine disk blade such as that of FIG. 2,

(6) FIG. 5 partially illustrates, seen from a top view, the overlap of the section in the foot of the rotor vane by the curvilinear neck of the foot for a turbine disk blade in accordance with the invention, and

(7) FIG. 6 partially represents, seen from a view from beneath, a low-pressure turbine rotor blade in accordance with the invention, such as that associated with FIG. 5.

(8) In all these figures, identical references can refer to identical or comparable elements.

(9) In addition, the various portions represented in the figures are not necessarily represented at a uniform scale, in order to make the figures more readable.

DETAILED ACCOUNT OF A PARTICULAR EMBODIMENT

(10) In the entire description it should be noted that axis 2 of turbomachine 1 is called its axis of radial symmetry (see FIG. 1). The axial direction of turbomachine 1 is the same as rotational axis 2 of turbomachine 1. A radial direction of turbomachine 1 is a direction perpendicular to axis 2 of turbomachine 1. In addition, unless otherwise stipulated, the adjectives and adverbs axial, radial, axially and radially are used in reference to the above-mentioned axial and radial directions, and the terms interior (or internal) and exterior (or external) are used in reference to a radial direction, such that the internal portion of an element is closer to axis 2 of turbomachine 1 than the external portion of the same element.

(11) FIGS. 1 to 4 have been described above in the part relating to the state of the prior art and to the invention's technical context.

(12) FIG. 5 partially illustrates, seen from a top view, the overlap of the section in the foot of rotor vane 30 by curvilinear neck 40 of the foot for a rotor disk blade 18 of turbine 8 in accordance with the invention, and FIG. 6 partially represents, seen from a view from beneath, a rotor blade 18 of a low-pressure turbine 8 in accordance with the invention associated with FIG. 5.

(13) The invention advantageously enables the section of neck 40 of the blade foot to be optimised in order that its overlap R2 with the section of rotor vane 30 in the foot is as effective as possible.

(14) In particular, as can be seen in FIG. 5, neck 40 has a curvilinear profile which defines, in a section in a plane perpendicular to radial direction 23, a curved shape extending in a curvilinear axis 42.

(15) This section of neck 40 advantageously overlaps at least 75% of the section of rotor vane 30, as a projection of the sections of neck 40 and of rotor vane 30 in a plane perpendicular to radial direction 23, where it joins platform 28. In this example of FIG. 5, overlap R2, symbolised by hatching, is even greater than 80% of the section of rotor vane 30 in the foot. It should be noted that platform 28 is roughly curvilinear, to enable the blade to be installed.

(16) Advantageously, by this means the field of stresses is better distributed over the surface of neck 40. In addition, this improved alignment facilitates the growth of grains in rotor vane 30, and a reduction of the stress concentrations due to the geometrical accidents.

(17) More specifically, neck 40 and blade foot root 24 are in this case machined to be curvilinear, in order to have the shape of an arc of a circle, using the same alignment as that of rotor vane 30.

(18) To facilitate installation of the parts curvilinear axis 42 includes a first portion of axis 42a configured to extend roughly parallel to rotational axis 2 of the turbine rotor disk, and a second portion of axis 42b forming a non-zero angle with rotational axis 2.

(19) More specifically, input angle , which can be seen in FIG. 6, on the upstream side of blade foot root 24, is chosen such that it is roughly zero relative to engine axis 2. In the same way, also to facilitate installation, output angle , which is located on the downstream side of root 24, formed between the second portion of axis 42b and engine axis 2, is chosen such that it is less than or equal to 45.

(20) The invention is, of course, not limited to the example embodiment which has just been described. Various modifications may be made to it by those skilled in the art.