A turbine rotor is fitted to a turbomachine and includes disks each containing a coupling portion with recesses each holding a root of a blade, and coupled to one another by a first annular ferrule attached to one of them close to the recesses, and second rotationally coupled ferrules, which are respectively coupled radially to the disks, which each consists of at least two semi-annular sectors, and which form with the associated disk a space which communicates with the recesses of the coupling portion of this latter disk. In addition, each first ferrule includes through-holes enabling air to enter this space, and then the recesses, intended to cool the coupling portion which couples its disk and the blade roots.