Rotor train torsional mode frequency tuning apparatus

Abstract

A rotor train torsional mode frequency tuning apparatus is provided and includes a rotor train and a coupling element. The rotor train includes first and second shafts and a coupling operably disposed between the first and second shafts and has a torsional mode frequency. The coupling element is disposed at the coupling and is configured to adjust the torsional mode frequency of the rotor train by a change in at least one of inertia and/or torsional stiffness in the rotor train.

1 . A rotor train torsional mode frequency tuning apparatus, comprising:
 a rotor train comprising first and second shafts and a coupling operably disposed between the first and second shafts,   the rotor train having a torsional mode frequency, and   the apparatus further comprising:   a coupling element disposed at the coupling and being configured to adjust the torsional mode frequency of the rotor train by a change in at least one of inertia and/or torsional stiffness in the rotor train.   
     
     
         2 . The apparatus according to  claim 1 , wherein the coupling element comprises a re-configurable mass. 
     
     
         3 . The apparatus according to  claim 1 , wherein the coupling element comprises a re-positionable mass. 
     
     
         4 . The apparatus according to  claim 1 , further comprising:
 a stationary element disposed proximate to the coupling element; and   a portable mass supportively disposable on the stationary element or the coupling element.   
     
     
         5 . The apparatus according to  claim 4 , wherein the coupling element is at least one of mechanically coupled to the coupling, press fit onto the coupling and integrally formed with the coupling and wherein the portable mass comprises an annular plate. 
     
     
         6 . A rotor train torsional mode frequency tuning apparatus, comprising:
 a coupling element fixedly disposed on a coupling operably disposed between first and second shafts; and   a portable mass supportively disposable on the coupling element,   the portable mass being movable to the coupling element to adjust at least one of a torsional stiffness and a rotational inertia of the second shaft such that a frequency of a torsional mode of the second shaft is substantially identical to a natural frequency of the torsional mode of the first shaft.   
     
     
         7 . The apparatus according to  claim 6 , wherein the coupling element is at least one of mechanically coupled to the coupling, press fit onto the coupling and integrally formed with the coupling. 
     
     
         8 . The apparatus according to  claim 7 , wherein the portable mass comprises an annular plate. 
     
     
         9 . An apparatus for rotor train torsional mode frequency tuning, the rotor train comprising:
 a coupling by which respective ends of shafts are connectable with each other, the apparatus comprising:   a coupling element fixedly disposed on the coupling; and   a portable mass supportively disposable on the coupling element,   the portable mass being movable to the coupling element to adjust at least one of a torsional stiffness and a rotational inertia of one of the shafts such that a frequency of a torsional mode of the one of the shafts is substantially identical to a natural frequency of the torsional mode of the other one of the shafts.   
     
     
         10 . The apparatus according to  claim 9 , wherein the shafts comprise:
 a first shaft coupled to a turbomachine; and   a second shaft coupled with the first shaft via the coupling.   
     
     
         11 . The apparatus according to  claim 10 , wherein the coupling comprises:
 a first coupling part associated with the end of the first shaft; and   a second coupling part associated with the end of the second shaft,   the coupling element being fixedly disposed on the second coupling part.   
     
     
         12 . The apparatus according to  claim 9 , wherein the coupling element is mechanically coupled to the coupling. 
     
     
         13 . The apparatus according to  claim 12 , wherein the coupling element comprises:
 a base ring mechanically coupled to the coupling; and   a retaining ring extending axially from the base ring,   an outer radial surface of the coupling element, an axial surface of the base ring and an inner radial surface of the retaining ring defining an annulus,   wherein the portable mass comprises an annular plate sized to fit in the annulus.   
     
     
         14 . The apparatus according to  claim 13 , wherein the rotor train comprises a stationary element disposed proximate to the coupling element, the portable mass being supportively disposable on the stationary element or the coupling element and movable from one to the other of the stationary element and the coupling element. 
     
     
         15 . The apparatus according to  claim 9 , wherein the coupling element is press fit onto the coupling. 
     
     
         16 . The apparatus according to  claim 15 , wherein the coupling element comprises:
 a base ring shrunk fit onto the coupling, the base ring including an axial portion and a radial portion,   an outer radial surface of the axial portion and an axial surface of the radial portion defining a pocket.   
     
     
         17 . The apparatus according to  claim 16 , wherein the portable mass comprises an annular plate sized to fit in the pocket. 
     
     
         18 . The apparatus according to  claim 9 , wherein the coupling element is integrally formed with the coupling. 
     
     
         19 . The apparatus according to  claim 18 , wherein the coupling element comprises:
 a first coupling part associated with the end of the first shaft;   a second coupling part associated with the end of the second shaft,   an axial surface of the first coupling part, an axial surface of the second coupling part and a radial surface of the second coupling part defining a recess.   
     
     
         20 . The apparatus according to  claim 19 , wherein the portable mass comprises an annular plate configured to be bolted into the recess.