Search

EP-4484710-B1 - DAMPER ELEMENT FOR A VIBRATION DAMPENING SYSTEM IN A BODY OPENING IN A ROTATING BLADE IN A TURBINE AND VIBRATION DAMPENING SYSTEM FOR A ROTATING BLADE

EP4484710B1EP 4484710 B1EP4484710 B1EP 4484710B1EP-4484710-B1

Inventors

  • Snider, Zachary John

Dates

Publication Date
20260513
Application Date
20240605

Claims (11)

  1. A damper element (170, 370) for a vibration dampening system (120, 320) in a body opening (160) in a rotating blade (114) in a turbine (108), the damper element (170, 370) comprising: a head member (172, 202, 224, 342) having an at least partially ramped surface (174, 204, 226, 344); characterized in the damper element (170, 370) further comprising a plurality of flexible legs (180) extending from the head member (172, 202, 224, 342), wherein each flexible leg (180) includes a radially extending body section (182) having an end section (184), the end section (184) having an outer end surface (186) and an inner end surface (188).
  2. The damper element (170, 370) of claim 1, wherein the at least partially ramped surface (174, 204, 226, 344) has an angle in a range between 25° and 55° degrees relative to an inner surface (162) of the body opening (160), and the inner end surfaces (188) of the plurality of flexible legs (180) have an angle in a range between 25° and 55° degrees relative to the inner surface (162) of the body opening (160).
  3. The damper element (170, 370) of claim 1, wherein the head member (172, 202, 224, 342) and, collectively, the radially extending body section (182) of the plurality of flexible legs (180) each have a first outer diameter, and the outer end surfaces (186) of the plurality of flexible legs (180) collectively define a second outer diameter that is larger than the first outer diameter.
  4. The damper element (170, 370) of claim 3, wherein the body opening (160) has an inner surface (162) having a third inner diameter, and wherein the second outer diameter is smaller than the third inner diameter, whereby, in a relaxed state, the plurality of flexible legs (180) pass freely within the body opening (160).
  5. The damper element (170, 370) of claim 3, wherein the inner end surfaces (188) of the plurality of flexible legs (180) are configured to receive the at least partially ramped surface (174, 204, 226, 344) of the head member (172, 202, 224, 342) of an adjacent damper element (170, 370), wherein under influence of a centrifugal force caused by rotation of the rotating blade (114) at higher than a predefined rotational speed, the head member (172, 202, 224, 342) of the adjacent damper element (170, 370) forces the outer end surfaces (186) of the plurality of flexible legs (180) into frictional engagement with an inner surface (162) of the body opening (160) to dampen vibration.
  6. The damper element (170, 370) of claim 5, wherein the outer end surfaces (186) of each flexible leg (180) frictionally engage with the inner surface (162) of the body opening (160) at a line.
  7. The damper element (170, 370) of claim 1, wherein the outer end surfaces (186) of each flexible leg (180) are parallel to the inner surface (162) of the body opening (160) in a relaxed state of the plurality of flexible legs (180).
  8. The damper element (170, 370) of claim 1, wherein adjacent radially extending body sections (182) of the flexible legs (180) define a slot (190) therebetween having a rounded radially outer extent (192).
  9. The damper element (170, 370) of claim 1, wherein the head member (172, 202, 224, 342) having the at least partially ramped surface (174, 204, 226, 344) has a frustoconical shape.
  10. The damper element (170, 370) of claim 1, wherein: the plurality of flexible legs (180) is parallel to a center axis of the damper element, the plurality of flexible legs (180) and the head member (172) have a same first outer diameter relative to the center axis at least where the plurality of legs extends from the head member, each flexible leg (180) includes a body section (182) having an end section (184), the end section (184) having, relative to the center axis, an outer end surface (186) and an inner end surface (188), the head member (172) and, collectively, the body sections (182) of the plurality of flexible legs (180) have the first outer diameter from the head member to the end sections (184) of the plurality of flexible legs (180), the outer end surfaces (186) of the end sections (184) of the plurality of flexible legs (180) collectively define a second outer diameter that is larger than the first outer diameter, the inner end surfaces (188) of the plurality of flexible legs (180) are configured to receive the at least partially ramped surface of a head member (172) of an adjacent identical damper element, and the damper element is configured such that, under influence of a centrifugal force at higher than a predefined rotational speed, the head member (172) of the adjacent identical damper element forces the outer end surfaces (186) of the plurality of flexible legs (180) into frictional engagement with an inner surface of the body opening (160) to dampen vibration.
  11. A vibration dampening system (120, 320) for a rotating blade (114), the vibration dampening system (120, 320) comprising: a plurality of stacked damper elements (170, 370) for positioning in a body opening (160) defined in the rotating blade (114), each damper element (170, 370) according to any one of claims 1 to 10.

Description

TECHNICAL FIELD The disclosure relates generally to dampening vibration in a rotating blade. More specifically, the disclosure relates to a vibration dampening system including a plurality of damper elements each having a plurality of flexible legs. The present invention relates to a damper element for a vibration dampening system in a body opening in a rotating blade in a turbine, and to a vibration dampening system for a rotating blade. BACKGROUND One concern in turbine operation is the tendency of the rotating turbine blades to undergo vibrational stress during operation. In many installations, turbines are operated under conditions of frequent acceleration and deceleration. During acceleration or deceleration of the turbine, the airfoils of the blades are, momentarily at least, subjected to vibrational stresses at certain frequencies and in many cases to vibrational stresses at secondary or tertiary frequencies. Nozzle airfoils experience similar vibrational stress. Variations in gas temperature, pressure, and/or density, for example, can excite vibrations throughout the rotor assembly, especially within the blade airfoils. Gas exiting upstream of the turbine and/or compressor sections in a periodic, or "pulsating," manner can also excite undesirable vibrations. When an airfoil is subjected to vibrational stress, its amplitude of vibration can readily build up to a point which may negatively affect gas turbine operations and/or component life. Stacked, solid damper elements in a turbine blade have been used to dampen vibration, but the centrifugal forces can result in locking of the damper elements together, reducing or eliminating their ability to dampen vibration. US 2021/172325 A1 relates to damping of turbomachine rotor blades; a stack of damper pins is provided inside a damping passage; one embodiment has generally cylindrical damper pins such that adjacent damper pins have complementary convex and concave surfaces, in contact. BRIEF DESCRIPTION The invention is defined by the claims. All aspects, examples and features mentioned below can be combined in any technically possible way. An aspect of the disclosure provides a damper element for a vibration dampening system in a body opening in a rotating blade in a turbine, the damper element comprising: a head member having an at least partially ramped surface; and a plurality of flexible legs extending from the head member, wherein each flexible leg includes a radially extending body section having an end section, the end section having an outer end surface and an inner end surface. Another aspect of the disclosure includes any of the preceding aspects, and the at least partially ramped surface has an angle in a range between 25° and 55° degrees relative to an inner surface of the body opening, and the inner end surfaces of the plurality of flexible legs have an angle in a range between 25° and 55° degrees relative to the inner surface of the body opening. Another aspect of the disclosure includes any of the preceding aspects, and the head member and, collectively, the radially extending body section of the plurality of flexible legs each have a first outer diameter, and the outer end surfaces of the plurality of flexible legs collectively define a second outer diameter that is larger than the first outer diameter. Another aspect of the disclosure includes any of the preceding aspects, and the body opening has an inner surface having a third inner diameter, and wherein the second outer diameter is smaller than the third inner diameter, whereby, in a relaxed state, the plurality of flexible legs pass freely within the body opening. Another aspect of the disclosure includes any of the preceding aspects, and the inner end surfaces of the plurality of flexible legs are configured to receive the at least partially ramped surface of the head member of an adjacent damper element, wherein under influence of a centrifugal force caused by rotation of the rotating blade at higher than a predefined rotational speed, the head member of the adjacent damper element forces the outer end surfaces of the plurality of flexible legs into frictional engagement with an inner surface of the body opening to dampen vibration. Another aspect of the disclosure includes any of the preceding aspects, and the outer end surfaces of each flexible leg frictionally engage with the inner surface of the body opening at a line. Another aspect of the disclosure includes any of the preceding aspects, and the outer end surfaces of each flexible leg are parallel to the inner surface of the body opening in a relaxed state of the plurality of flexible legs. Another aspect of the disclosure includes any of the preceding aspects, and adjacent radially extending body sections of the flexible legs defined a slot therebetween having a rounded radially outer extent. Another aspect of the disclosure includes any of the preceding aspects, and the head member having the at least partially ramped surfac