Turbomachine rotor wheel

1. A rotor wheel for a turbomachine, the wheel comprising:

a disk carrying blades having roots engaged and held in an annular recess in an outer peripheral surface of the disk, an outer annular surface of the outer peripheral surface of the disk having an upstream outer annular surface and a downstream outer annular surface located upstream and downstream from said annular recess, respectively, the roots being connected to platforms surrounding the outside of the outer peripheral surface of the disk and designed to co-operate with an annular sealing gasket mounted in an annular groove of the downstream outer annular surface of the outer peripheral surface of the disk,

wherein, at rest, the annular gasket bears against inner surfaces of the blade platforms and exerts a resilient force on the blade platforms so as to hold the blades in a proper position for operation in which said inner surfaces of the blade platforms are spaced from said downstream outer annular surface and in which said blade platforms are in abutment against said upstream outer annular surface of the outer peripheral surface of the disk, the annular gasket in the free state having an outside diameter greater than that of its mounting groove, and its hardness is determined so as to urge the blades into their proper position for operation and so as to allow the blades to be moved circumferentially in their annular mounting recess,

wherein the gasket has a section that is substantially X-shaped or H-shaped, and includes two outer peripheral lips which project out from the groove and which abut against the blade platforms and two inner peripheral lips which bear against the bottom of the groove when the gasket is mounted in the groove, said gasket further comprising upstream and downstream flat annular surfaces which are parallel to upstream and downstream gasket surfaces of the groove and are in abutment against the upstream and downstream gasket surfaces.

2. A wheel according to claim 1 , wherein the gasket is symmetrical in shape about its transverse midplane.

3. An annular sealing gasket for a rotor wheel according to claim 1 , the gasket having, in the free state, an outside diameter greater than the outside diameter of its annular mounting groove and presenting hardness on the Shore A scale lying in the range 50 to 100.

4. A turbomachine compressor including at least one rotor wheel according to claim 1 .

5. A turbomachine such as an airplane turbojet or turboprop, the turbomachine including at least one rotor wheel according to claim 1 .

6. A wheel according to claim 1 , wherein the hardness of the gasket is determined such that an angular position of the blades when the turbomachine is at rest is substantially the same as the angular position of the blades when the turbomachine is in operation.

7. A wheel according to claim 1 , wherein inner surfaces of the blade platforms include an annular rib which projects towards an axis of the rotor and abuts against said upstream outer annular surface of the outer peripheral surface of the disk.