AXIAL FLOW TURBINE ASSEMBLY AND A MULTI-STAGE SEAL

A labyrinth seal positioned between a turbine rotor and inner platforms of vanes of a turbine assembly controls the leakage flow of fluid from a chamber to the flowpath through the turbine assembly. The labyrinth seal is divided into two parts by a second chamber positioned between two adjacent fins of the labyrinth seal. The chamber is located at a predetermined position in the seal such that a predetermined pressure, sufficient to supply fluid to cool a stage of turbine rotor blades in the turbine assembly, is selected. The second chamber is interconnected to the turbine blades by passages, and a chamber. The pressure of fluid in the second chamber is less than that which would normally exist in the second chamber, because fluid is being supplied from the second chamber to the second stage of turbine rotor blades. The flow of fluid from the second chamber, through the second part of the labyrinth seal, to the flowpath through the turbine is therefore reduced.