accumulation segments and also the moving blades subjected to the highest stress by the fuel gas the requisite cooling air flow is removed from the last stage of the compressor not shown it is located to the right of the first moving blade ring 5 of the turbine whereupon a swirl blade cascade which is arranged between the compressor and the first turbine stage and is described in de a no 3 424 139 mentioned at the beginning gives the cooling air flow a tangential velocity component which is the same as the peripheral velocity of the rotor cooling channels thus the cooling air at the relative velocity zero in the peripheral direction relative to the turbine rotor enters substantially axially as indicated by the velocity arrow 16 through a row of cooling air bores 15 into the cooling channel system of the turbine via the cooling air bores 15 which are provided in large numbers distributed over an annular flat end face 17 in front of the first moving blade ring the cooling air passes into an annular groove 18 which widens in a wedge shape in cross section toward its periphery and out of the latter through a row of interrupted annular gaps 19 in front of the first moving blade ring 5 and between two each of the following moving blade rings and also finally through channels 20 in the area of the blade roots into blade root channels 21 of the last moving blade ring 9 the annular gaps 19 are defined by the.