Turbine casing cooling channel with cooling fluid flowing upstream

Turbine (100), in particular a gas turbine, comprising an inner casing (101) to which at least a stator vane of a turbine section is mountable and an outer casing (102), which is arranged around the inner casing (101) in such a way that an outer cooling channel (103) is formed between the inner casing (101) and the outer casing (102). The outer cooling channel (103) comprises a fluid inlet (104) through which a cooling fluid is injectable from an outer volume (Vo) of the turbine (100) into the outer cooling channel (103). The cooling channel (103) comprises a fluid outlet (105) such that the cooling fluid is exhausted into an inner volume (Vi) of the turbine (100). The fluid inlet (104) is located with respect to the fluid outlet (105) such that the cooling fluid inside the outer cooling channel (103) comprises a flow direction which has a component that is orientated in opposite direction with respect to a main flow direction (106) of a working fluid of the turbine (100).