STEAM TURBINE BUCKET WITH FRICTION DAMPING PIN

245582

STEAM TURBINE BUCKET WITH FRICTION DAMPING PIN

BACKGROUND

The present invention relates generally to turbines having a plurality of circumferentially-spaced buckets, and more particularly to bucket damper pins for damping bucket vibrations.

Generally, turbines include a rotor comprises a plurality of rotor wheels, each of which mounts a plurality of circumferentially-spaced buckets. The buckets each typically include a turbine blade, a platform, a shank, and a dovetail. During operation of an engine, vibrations are introduced into the turbine buckets. Such vibrations need to be dissipated to avoid premature failure of the buckets.

In the steam turbine bucket design, such as but not limited to the control stage of a steam turbine, fork root type integral cover buckets may be utilized with forced pin assemblies as shown in Figure 1. However, such conventional techniques have time consuming assembly procedures. Further, control of the pins interference is very difficult. Additionally, peripheral operational speed is limited by root configuration of the turbine bucket.

An advantage of this solution is to leave limited amount of tangential space for the buckets to vibrate, limiting high cycle fatigue risks.

It would be desirable to increase rotational speed (tip speed) capability of the turbine and guarantee cover contact through pin and damped modal response. The increase of rotational speed is obtained changing root from fork type to firtree type, reducing mean stress values and allowing speed increase capability. The modifi...