Flowpath sealing and streamlining configuration for a turbine

Abstract

The root region of a flowpath through a turbine includes a sealing configuration for minimizing leakage flow and secondary aerodynamic losses. Entrance and exit root radial seals are provided between upstream and downstream nozzles at locations radially inwardly of the root region of the flowpath to minimize radial leakage flow. To minimize intrusion flow into the flowpath from rotor pumping action and consequent aerodynamic losses, an exit flow guide on each bucket turns the exiting radial flow in a predominantly axial direction. Additionally, the upstream bucket root radius and nozzle root radius are faired or tapered to minimize the possibility of a protuberance projecting into the flowpath at steady state operation. An additional entrance root axial fin is provided on the buckets to reduce the flow coefficient and afford further reduction in leakage flow.