Blade platform vibration dampers

• US 3,881,844 A
• Filed: 05/28/1974
• Issued: 05/06/1975
• Est. Priority Date: 05/28/1974
• Status: Expired due to Term

• Current Assignee: John D. Hennessey, Richard Beal
• Original Assignee: John D. Hennessey, Richard Beal
• Inventors: Hennessey, John D., Beal, Richard
• Primary Examiner(s): Powell, Jr., Everette A.
• Application Number:
  US05/473,680
• Time in Patent Office: 343 Days
• Field of Search: 416/144,145,500,219-221,215,218
• US Class Current: 416/145
• CPC Class Codes: F01D 5/22 Blade-to-blade connections, e.g. for damping vibrations
• CPC Class Codes: F01D 5/24 using wire or the like
• CPC Class Codes: F01D 5/3038 the slot having inwardly directed abutment faces on both sides
• CPC Class Codes: F05D 2260/96 Preventing, counteracting or reducing vibration or noise
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft
• CPC Class Codes: Y10S 416/50 Vibration damping features

Abstract

A turbomachinery assembly equipped with circumferentially disposed blades, having integral platforms and dovetails, is provided with a vibration damping means disposed circumferentially about the perimeter of a dovetail engaging the disc between the disc and the blade platforms. The vibration damper, in one embodiment, comprises a spiraled encasing means wound around a flexible core element. As the vibration damper is centrifugally forced into contact with the blade platform, blade platform vibratory energy is transmitted to the damping means and is dissipated as heat through relative frictional movement between adjacent portions of the encasing means and between the encasing means and the flexible core.

Claims

1. In a turbomachinery assembly including a fluid flow path, generally cylindrical support means, a plurality of radially extending blades attached to said support means, each of said blades comprising an airfoil, mounting means for attaching said blade to said support means, and a platform disposed in a spaced relationship with said support means and positioned between the airfoil and the mounting means for partially defining the flow path, vibration damping means comprising:

encasing means disposed between said support means and said blade platform, being in frictional contact with and capable of exerting radial pressure on said blade platforms during operation in the fluid flow path, for damping blade platform movement; and

a flexible core element cooperating with and movable with respect to said encasing means, and in frictional contact therewith.

2. The vibration damping means of claim 1 wherein said encasing means comprises a flexible coil disposed in a spiral around said core element, predetermined of said turns of said spiral being in frictional contact with adjacent turns.

3. The vibration damping means of claim 2 wherein said core element is segmented, each segment disposed generally about a portion of the circumference of said support means and wherein said segments include restraining means to preclude substantial circumferential movement of said core element segments with respect to said support means.

4. The vibration damping means of claim 3 wherein said restraining means comprises a slot in said support means and wherein a predetermined portion of each segment is disposed at an angle to the remainder of the segment and keyed into said slot.

5. The vibration damping means of claim 1 wherein the encasing means comprises a plurality of members generally encircling said core element, said members movable relative to one another and to said core, and predetermined of said members in frictional contact with one another.

6. The vibration damping means of claim 5 wherein the plurality of members generally encircling the core are disposed at some angle other than 90* to the longitudinal axis of the core element.

7. The vibration damping means of claim 6 wherein the members generally encircling the core are discrete annuli.

8. The vibration damping means of claim 5 wherein said core element is segmented, each segment disposed generally about a portion of the circumference of said support means and wherein said segments include restraining means to preclude substantial circumferential movement of said core element segments with respect to said support means.

9. The vibration damping means of claim 8 wherein said restraining means comprises a slot in said support means and wherein a predetermined portion of each segment is disposed at an angle to the remainder of said segment and keyed into said slot.

10. The vibration damping means of claim 1 wherein said vibration damping means cooperates with said platform and said support structure to create a labyrinth flow path for inhibiting fluid flow between said support means and said blade platform.

11. The tUrbomachinery assembly of claim 10 further characterized in that said support means comprises a rotatable disc, and wherein said radial pressure is a result of centrifugal forces on said vibration damping means.

12. The vibration damping means of claim 11 wherein said disc includes a circumferential recess and wherein said vibration damping means is partially disposed within said recess.

13. The vibration damping means of claim 12 wherein said vibration damping means comprises a severed ring disposed circumferentially between said rotatable disc and said blade platform.