Vibration dampening device disposed on a shroud member for a twisted turbine blade

Claim 1

A rotor having an annular array of substantially radially extending twisted blades thereon, each of said blades having a radially outwardly extending tenon thereon, a first and a second shroud member extending circumferentially about said array, each shroud member engaging a predetermined plurality of tenons to define a first and a second blade group within said annular blade array, a substantially axial gap disposed between said shroud members, said first and said second shrouds each having a circumferential step thereon, said steps defined by a substantially radial face and a substantially axial lip disposed on each shroud, a snubber member disposed on said circumferential step on said first shroud, a portion of said snubber extending across said axial gap and circumferentially overlapping a portion of said circumferential step on said second shroud, a predetermined axial clearance being defined between said snubber and said radial face on said second shroud, said axial clearance closing so as to cause abutment between said second shroud and said snubber as said annular array of twisted blades is subjected to an untwist force during operation of said rotor, said abutment of said snubber and said second shroud inhibiting untwisting of said blades due to said untwist force and simultaneously providing a friction interface to limit circumferential motion between said snubber and said second shroud.