Turbine engine rotor shaft comprising an improved heat exchange surface

1. A turbine engine comprising:

a combustion chamber;

a turbine engine rotor shaft; and

an environment of said turbine engine rotor shaft submitted to heat caused by a proximity of said combustion chamber,

said turbine engine rotor shaft including at least one portion which is thermally shielded from said environment of said turbine engine rotor shaft and a portion which is thermally exposed to said environment of said turbine engine rotor shaft, said portion which is thermally exposed including a heat exchange portion, an outer periphery of the heat exchange portion including a determined diameter and forms a free surface for heat exchange with the environment of said turbine engine rotor shaft,

wherein the outer periphery of the heat exchange portion of said turbine engine rotor shaft includes a plurality of shaft surface structure irregularities which are designed to provide a first heat exchange surface of said turbine engine rotor shaft which is greater than a second heat exchange surface which is associated with a periphery of a cylinder including a same determined average diameter, and

wherein at least a portion of the outer periphery of the heat exchange portion of said turbine engine rotor shaft that includes the plurality of shaft surface structure irregularities is disposed along a length of a compressor of the turbine engine.

2. The turbine engine according to claim 1 , wherein the shaft surface structure irregularities include at least bumps.

3. The turbine engine according to claim 2 , wherein the bumps include at least elements which are deposited on the outer periphery of the heat exchange portion of said turbine engine rotor shaft.

4. The turbine engine according to claim 3 , wherein the elements include particles deposited on a substrate adhering to the outer periphery of the heat exchange portion of said turbine engine rotor shaft that are sub-micron-size ceramic particles which are sprayed onto said turbine engine rotor shaft by a suspension plasma spraying method onto the substrate adhering to the outer periphery of the heat exchange portion of said turbine engine rotor shaft, or metal particles glued to the substrate adhering to the outer periphery of the heat exchange portion of said turbine engine rotor shaft.

5. The turbine engine according to claim 1 , wherein the shaft surface structure irregularities include at least one cavity.

6. The turbine engine according to claim 5 , wherein the outer periphery of the heat exchange portion of said turbine engine rotor shaft includes at least one circular groove forming said at least one cavity.

7. The turbine engine according to claim 5 , wherein the outer periphery of the heat exchange portion of said turbine engine rotor shaft includes at least one longitudinal groove forming said at least one cavity.

8. The turbine engine according to claim 5 , wherein the outer periphery of the heat exchange portion of said turbine engine rotor shaft includes at least one thread including a determined nominal pitch and diameter forming said at least one cavity.

9. The turbine engine according to claim 1 , wherein said turbine engine rotor shaft is a turbine engine rotor shaft of a low-pressure body passing through at least one sleeve of said turbine engine, the sleeve shielding a portion of said turbine engine rotor shaft from said low-pressure body, and wherein the heat exchange portion of said turbine engine rotor shaft is formed outside the sleeve.

10. The turbine engine according to claim 9 , wherein the heat exchange portion of said turbine engine rotor shaft includes, at a junction thereof with an upstream end of the sleeve, at least one longitudinal groove or one thread including a determined pitch, which is designed to suck a flow of air inside said sleeve.

11. The turbine engine according to claim 4 , wherein the particles are the sub-micron-size ceramic particles.