Turbine wheel in a turbine engine

1. A turbine wheel, comprising:

a plurality of blades having roots engaged axially and held radially in slots in a disk alternating between teeth of the disk, the blades having platforms arranged circumferentially end to end with a circumferential clearance therebetween and each platform being connected to a blade root by a tang, the blade root presenting a dovetail shape in cross-section, the disk including an arm extending downstream and including an annular radial attachment flange at an end thereof, the radial attachment flange including a bolt hole,

wherein each platform is extended at an upstream end by an upstream radial wall connected at a radially inner end thereof to the blade root and is extended at a downstream end by a downstream radial wall connected at a radially inner end thereof to the blade root, an upstream lip extending upstream from the upstream radial wall and a downstream lip extending downstream from the downstream radial wall,

wherein a cavity is defined between two circumferentially adjacent blades, the cavity being circumferentially delimited by two adjacent tangs of the two circumferentially adjacent blades, radially delimited by one of the teeth of the disk and two adjacent platforms of the two circumferentially adjacent blades, and axially delimited by the upstream and downstream radial walls of the two circumferentially adjacent blades,

wherein each blade comprises two separator walls extending from the tang in a circumferential direction and from upstream to downstream, the separator walls being arranged end to end circumferentially with a circumferential clearance so as to divide the cavity into a radially inner cavity and a radially outer cavity between two consecutive tangs, for each pair of blades, the circumferential clearance between two ends of platforms is substantially similar to the circumferential clearance between the two circumferential ends of the two separator walls located radially inside with respect to the said two platforms.

2. A turbine wheel according to claim 1 , wherein said separator walls are formed substantially halfway radially between the blade roots and the platforms.

3. A turbine wheel according to claim 1 , wherein said separator walls extend substantially perpendicularly to the radial tangs of the blades.

4. A turbine wheel according to claim 1 , wherein the separator walls are connected to the tang and to the upstream and downstream radial walls.

5. A low pressure turbine engine turbine, comprising:

a turbine wheel according to claim 1 ; and

means for bringing cooling air from the inside of the turbine and leading into the radially inner cavity between two adjacent blades.

6. A turbine according to claim 5 , wherein said turbine wheel forms a first wheel at an upstream end of the low pressure turbine, and wherein an annular gap is arranged between said wheel and a substantially circumferential stator wall upstream therefrom, in substantially axial alignment with the platforms of the blades of the wheel to allow cooling air to flow from the inside of the turbine into said annular gap.

7. A turbine engine comprising:

a turbine according to claim 5 .

8. A turbine wheel, comprising:

a plurality of blades having roots engaged axially and held radially in slots in a disk alternating between teeth of the disk, the blades having platforms arranged circumferentially end to end with a circumferential clearance and each platform being connected to a blade root by a tang, the blade root presenting a dovetail shape in cross-section, the disk including only one arm extending upstream and including an annular radial attachment flange at an end thereof, the radial attachment flange including a bolt hole,

wherein an upstream annular plate is mounted on an upstream face of the disk and a downstream annular plate is mounted on a downstream face of the disk, the upstream annular plate being held in an upstream groove provided in the platform and the downstream annular plate being held in a downstream groove provided in the platform,

wherein a cavity is defined between two circumferentially adjacent blades, the cavity being circumferentially delimited by two adjacent tangs of the two circumferentially adjacent blades, radially delimited by one of the teeth of the disk and two adjacent platforms of the two circumferentially adjacent blades, and axially delimited by the upstream and downstream annular plates, and

wherein each blade comprises two separator walls extending from the tangs in a circumferential direction and from upstream to downstream, the separator walls being arranged end to end circumferentially with a circumferential clearance so as to divide the cavity into a radially inner cavity and a radially outer cavity between two consecutive tangs, for each pair of blades, the circumferential clearance between two ends of platforms is substantially similar to the circumferential clearance between the two circumferential ends of the two separator walls located radially inside with respect to the said two platforms.

9. A low pressure turbine engine turbine, comprising:

a turbine wheel according to claim 8 ; and

means for bringing cooling air from the inside of the turbine and leading into the radially inner cavity between two adjacent blades.

10. A turbine according to claim 9 , wherein said turbine wheel forms a last wheel at a downstream end of the low pressure turbine, and wherein an annular gap is arranged between said wheel and a substantially circumferential stator wall downstream therefrom, in substantially axial alignment with the platforms of the blades of the wheel to allow cooling air to flow from the inside of the turbine into said annular gap.

11. A turbine engine, comprising:

a turbine according to claim 10 .