Abstract: A stage of an axial flow turbine includes a plurality of spaced apart buckets and a plurality of spaced apart nozzle partitions, each plurality respectively circumferentially aligned about and axially spaced from each other along a rotor of the turbine. The nozzle partitions are circumferentially spaced such that a minimum throat extends a predetermined radial distance from the root, thereby forming a converging-diverging flow passageway between nozzle partitions. The trailing edge of the nozzle partitions are disposed to include axial and tangential lean with respect to the rotor. Buckets include a plurality of covers respectively connecting the tips and having a single outward radially extending sealing rib on the radially outer surface of each cover, wherein each rib is tangentially aligned with respective adjacent ribs. Buckets are overtwisted to compensate for untwist at operational speed to achieve optimum efficiency.

Abstract: A diaphragm for an axial flow turbine includes a plurality of spaced apart nozzle partitions and an inner member for fixedly securing the nozzle partitions. The inner member is contoured to direct elastic fluid flow radially inward. The nozzle partitions are spaced such that a minimum throat extends a predetermined radial distance from the root, thereby forming a converging-diverging flow passageway between nozzle partitions. The trailing edge of the nozzle partitions are disposed to include axial and tangential lean with respect to the rotor of the turbine.