THERMAL SHIELDING IN A GAS TURBINE

摘要

A turbine blade has a body enclosing a labyrinth of internal channels for the circulation of coolant received through an inlet (34) integrally formed in a terminal portion of the blade root. The labyrinth comprises; an inlet (34) arranged on an axially upstream face of the terminal portion leading to an upstream duct portion having a first section (35) adjacent the inlet and a second section (36) axially downstream of the first, the second section (36) having a reduced cross section compared to the first section. A leading edge passage (31) intersects the first section (35) and extends through the blade body towards the tip of the blade. A main blade passage (32) intersects the second section (36). A trailing edge passage (33) intersects with a downstream duct portion (37) which is in axial alignment with but separate from the second section (36) and a channel (38) connects the second section (36) with the downstream duct portion (37). The channel (38) has a reduced cross section compared to the second section (36) and the downstream duct portion (37). The inlet (34) has an inverted keyhole shape and this inverted key-hole cross section extends through the upstream duct portion first section (35).