formed from rotor blades 15 follows a stator blade row 13 in each case as seen in the flow direction of a hot gas 11 which is produced in the annular combustion chamber 6 the stator blades 12 are fastened on the stator whereas the rotor blades 15 of a row 14 are attached on the rotor 3 by means of a turbine disk in each case a generator or a driven machine not shown is coupled to the rotor 3 in order to reheat the hot gas 11 which flows through the hot gas space 18 in the region of the turbine unit 8 according to the in situ blade reheat process the walls which delimit the hot gas space 18 and or the blade airfoils of turbine blades 20 which are arranged in the hot gas space 18 are formed as components 22 in a suitable manner for it for this purpose fig2 shows the blade airfoil 24 in the form of an airfoil profile of the cast turbine blade 20 which can be formed as a rotor blade 15 or as a stator blade 12 the blade airfoil 24 extends along a chord with a chord length from a leading edge 26 to a trailing edge 28 as seen in the flow direction of the hot gas 11 in this case the blade airfoil 24 has a suction side blade wall 30 and a pressure side blade wall 32 which connect the leading edge 26 to the trailing edge 28 in each case a cavity 34 which is enclosed by the blade.