Friday, December 5, 2008

High Pressure Turbine

The LM6000 high pressure turbine (HPT) is an air-cooled, two-stage design with demonstrated high efficiency. The high pressure turbine system consists of the high pressure turbine rotor and the stage 1 and stage 2 high pressure turbine nozzles. The high pressure turbine assembly drives the high pressure compressor rotor by extracting energy from the hot-gas path stream.

The high pressure turbine rotor assembly consists of the stage 1 disk and integral shaft, a conical impeller spacer with cover, a thermal shield and a stage 2 disk. Forward and aft rotating air seals are assembled to the high pressure turbine rotor and provide air-cooled cavities around the rotor system. An integral coupling nut and pressure tube is used to form and seal the internal cavity. The rotor disks and blades are cooled by a continuous flow of compressor-discharged air. The air is directed to the internal cavity of the rotor through diffusor vanes that are part of the forward seal system.

The stage 1 disk/shaft design combines the rotor forward shaft and stage 1 disk a one-piece unit. Torque is transmitted to the compressor rotor through an internal spline at the forward end of the disk/shaft. The stage 1 blades fit into axial, dovetail slots in the disk. The stage 2 disk incorporates a flange on the forward side for transmitting torque to the stage 1 disk. An aft flange supports the aft air seal and the integral coupling nut and pressure tube. Stage 2 blades fit into axial, dovetail slots in the disk.

Internally cooled turbine blades are used in both stages. Both stages of blades are cooled by compressor-discharged air flowing through the blade shank into the air foil. The cone-shaped impeller spacer serves as the structural support between the turbine disks. The spacer also transmit torque from the stage 2 disk to the stage 1 disk. The catenary-shaped thermal shield forms the outer portion of the turbine rotor cooling air cavity and serves as the rotating portion of the interstage gas path seal.