Abstract: A turbine nozzle cooling sub-system is provided. The sub-system includes at least one turbine nozzle segment. The segment includes an arcuate, radially outermost endwall, an arcuate, radially innermost endwall, and at least one airfoil vane. The endwalls each include at least one open passage. The airfoil vane extends between and is coupled to the endwalls. The vane further includes a cavity, a leading edge, a trailing edge, and an airfoil vane external surface. The cavity includes an airfoil vane internal surface and a plurality of turbulators. The cavity and the open passages are in flow communication such that an airfoil cooling air stream flow is facilitated. The sub-system also includes at least one diffuser in flow communication with a compressor assembly and the segment. The diffuser includes at least one diffuser wall and cavity. The diffuser wall extends from the compressor assembly to the segment such that a channeling of the airfoil cooling air stream to the segment is facilitated.

Abstract: A method of operating a gas turbine having inner and outer shells, with the inner shell being radially movable relative to rotor bucket tip passage in the inner shell for flowing a thermal medium. A pair of passage portions are formed in each of the aft and forward inner shell sections with axially communicating passageways between the passage portions. A thermal medium, preferably from an off-turbine site, is provided for flow through the second-stage aft inner shell section, along axial passageways along the mid-line of the inner shell to a first passage portion of the forward inner shell section. Cross-over paths flow the thermal medium from the first passage portions to second circumferentially extending passage portions of the forward inner shell section, in turn, in communication with axial passageways extending from the forward section to the aft section. A second pair of passage portions flow the thermal medium to an outlet in the aft section.

Abstract: A leaf seal assembly is secured to the trailing edge of a shroud segment for sealing between the shroud segment and the leading edge side wall of a nozzle outer band. The leaf seal includes a circumferentially elongated seal plate biased by a pair of spring clips disposed in a groove along the trailing edge of the shroud segment to maintain the seal plate in engagement with the flange on the leading edge side wall of the nozzle outer band. The leaf seal plate and spring clips receive pins tack-welded to the shroud segment to secure the leaf seal assembly in place.

Abstract: A turbine shroud cooling cavity is partitioned to define a plurality of cooling chambers for sequentially receiving cooling steam and impingement cooling of the radially inner wall of the shoud. An impingement baffle is provided in each cooling chamber for receiving the cooling media from a cooling media inlet in the case of the first chamber or from the immediately upstream chamber in the case of the second through fourth chambers and includes a plurality of impingement holes for effecting the impingement cooling of the shroud inner wall.