Abstract: Applicants have identified and unexpected mechanism which contributes to solid particle erosion of the trailing edge of spaced apart aerodynamically shaped nozzle partitions in an axial fluid flow turbine. Particles entrained in the fluid flow pass through passages between nozzle partitions, strike rotating buckets and rebound upstream to impinge upon the suction side of the nozzle partitions in the trailing edge region. Accordingly, a nozzle partition includes a protection device disposed over at least a portion of the suction side of the nozzle partition, preferably from the trailing edge to the throat, for preventing solid particle erosion of the partition.

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.