Turbine blade damping device with controlled loading

A mid-span damping structure in a turbomachine rotor having a rotor disk and a plurality of blades, the mid-span damping structure comprising:

• an elongated snubber element including a first snubber end rigidly attached to a first blade and extending toward an adjacent second blade, and an opposite second snubber end positioned adjacent to a cooperating surface at least partly formed on a side surface of the second blade and defining an axially curved bearing surface;
• the snubber element having a centerline extending radially inwardly in a direction from the first blade toward the second blade along a portion of the snubber element between the first end and a midway point between the first and second blades, and extending radially outwardly from the midway point to the second snubber end;
• and
• wherein rotational movement of the rotor effects relative movement between the second snubber end and the cooperating surface to position the second snubber end in frictional engagement with the cooperating surface with a predetermined damping force determined by a centrifugal force on the snubber element.

A damping structure in a turbomachine rotor having a rotor disk and a plurality of blades, the damping structure comprising:

• an elongated snubber element including a first snubber end rigidly attached to a first blade and extending toward an adjacent second blade, and an opposite second snubber end positioned adjacent to a cooperating surface at least partly formed on the second blade, a gap being formed between the second snubber end and the cooperating surface when the rotor is stationary;
• the snubber element having a centerline extending radially inwardly in a direction from the first blade toward the second blade along at least a portion of the snubber element between the first and second snubber ends;
• wherein the centerline of the snubber element comprises first and second linear centerline segments and an inflexion angle between the centerline segments at a midway point on the snubber element between the first and second blades, the first centerline segment angling radially inwardly from the first snubber end to the midway point and the second centerline segment angling radially outwardly from the inflexion angle defined at the midway point to the second snubber end;
• wherein the cooperating surface defines an axially extending area for accommodating axial movement of the second snubber end along the cooperating surface as the first and second blades untwist during rotor spin-up;
• and
• wherein rotational movement of the rotor effects relative movement between the second snubber end and the cooperating surface to position the second snubber end in frictional engagement with the cooperating surface with a predetermined damping force determined by a centrifugal force on the snubber element.