A turbine blade having a body enclosing a plurality of internal channels for the passage of coolant gas received through an inlet (32) formed in the blade root, comprising a gas flow separator (30), configured to separate coolant gas into first (35) and second (36) gas flows. The gas flow separator is configured to separate the first and second gas flows such that the level of contaminants in the first gas flow is lower than the level of contaminants in the second gas flow.