Turbine blisk rim friction finger damper

Abstract

A damper for reducing vibrations in an integrally bladed turbine disk is provided. The damper includes an annular member and a plurality of fingers. The annular member is configured so that it is coupled to a face of the integrally bladed turbine disk. The plurality of fingers are circumferentially spaced around the annular member. Each of the fingers includes a base portion which is coupled to the annular member and extends radially therefrom. Each of the fingers is tangentially movable relative to the annular member when the turbine disk vibrates in a diametral mode shape such that the plurality of fingers contacts a surface of the turbine disk to absorb vibrations.

Description

TECHNICAL FIELD[0001]The present invention relates generally to turbines and more particularly to a damper for dampening vibration in a turbine disk.BACKGROUND OF THE INVENTION[0002]Discussion[0003]Turbine disks are commonly subject to high cycle fatigue failure due to resonant vibration and fluid-structure instabilities. Disks have several critical speeds wherein operation of the disk at any one of these speeds creates an amplified traveling wave within the disk, inducing potentially excessive dynamic stresses. At each of these critical speeds the wave is fixed with respect to the housing and can be excited by any asymmetries in the flow field. The resulting resonant vibration prevents the operation of conventional turbine disks at critical speeds. Fluid-structure instabilities arise due to coupling between the surrounding fluid and the disk, which can also induce excessive stresses and prevent operation at speeds above a threshold stability boundary.[0004]In conventional turbine d...

AI Technical Summary

Benefits of technology

[0007]It is one object of the present invention to provide a damper for an integrally bladed turbine disk which employs a plurality of fingers to reduce the vibration of an integrally bladed turbine disk. The damper is primarily intended to reduce vibration when the integrally bladed turbine disk vibrates in a diametral mode shape. However, the damper is also effective in reducing the vibration of turbine blades mounted on the disk rim.

[0008]It is another object of the present invention to provide a damper having a profile which applies a frictional contact force continuously over a disk profile to direct the contact force normal to the disk surface.

Problems solved by technology

Turbine disks are commonly subject to high cycle fatigue failure due to resonant vibration and fluid-structure instabilities.

Disks have several critical speeds wherein operation of the disk at any one of these speeds creates an amplified traveling wave within the disk, inducing potentially excessive dynamic stresses.

The resulting resonant vibration prevents the operation of conventional turbine disks at critical speeds.

Fluid-structure instabilities arise due to coupling between the surrounding fluid and the disk, which can also induce excessive stresses and prevent operation at speeds above a threshold stability boundary.

This damping mechanism, however, is not feasible for integrally bladed turbine disks (blisks) unless radial slots are machined between each blade to introduce blade shank flexibility.

The added complexity of the slots increases the rim load on the turbine disk and defeats some of the cost, speed and weight benefits of the blisk.

Consequently, the lack of a blade attachment interface results in a significant reduction in damping and can result in fluid-structure instability at speeds other than the disk standing wave critical speeds.

This method of friction damping, however, is not feasible at high rim speeds because the centrifugal force on the damper ring is of sufficient magnitude to cause the damper to lock-up against the rim.

Images