US Patent 10443402 Thermal shielding in a gas turbine

A turbine blade includes a labyrinth of internal channels for the circulation of coolant received through an inlet formed in a terminal portion of the blade root and leading to a duct-defined wall. A first passage intersects the duct and extends through the blade towards a tip. An end of the first passage is arranged to capture incoming coolant flow. A second passage intersects the duct at a position downstream of the first passage intersection. The duct and/or the passage intersections are configured to create a pressure drop in the duct in the direction from the inlet to the second passage intersection. In an axial direction, a duct wall terminates at a position between the inlet and the second passage intersection.