Blade disk arrangement for blade frequency tuning

• US 9,410,436 B2
• Filed: 12/07/2011
• Issued: 08/09/2016
• Est. Priority Date: 12/08/2010
• Status: Active Grant

• Current Assignee: Pratt & Whitney Canada Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Pratt & Whitney Canada Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Kulathu, Ram, Abate, Aldo
• Primary Examiner(s): White, Dwayne J
• Assistant Examiner(s): WHITE, ALEXANDER A
• Application Number:
  US13/313,485
• Publication Number:
  US 20120148401A1
• Time in Patent Office: 1,707 Days
• Field of Search: 416/1, 416/61, 416/62, 416/144, 416/145, 416190-193 A, 416/500
• US Class Current: 1/1
• CPC Class Codes: F01D 5/10 Anti- vibration means specially adapted for radial flow machines or engines F01D5/04
• CPC Class Codes: F01D 5/26 Antivibration means not restricted to blade form or construction or to blade-to-blade connections or to the use of particular materials
• CPC Class Codes: F04D 29/324 Blades
• CPC Class Codes: F04D 29/329 Details of the hub
• CPC Class Codes: F04D 29/388 characterised by construction
• CPC Class Codes: F04D 29/668 damping or preventing mechanical vibrations
• CPC Class Codes: F05D 2230/10 by removing material
• CPC Class Codes: F05D 2230/30 with deposition of material
• CPC Class Codes: F05D 2260/961 by mistuning rotor blades or stator vanes with irregular interblade spacing, airfoil shape

Abstract

A gas turbine engine and a method of tuning a rotor in the gas turbine engine wherein the rotor includes an array of blades extending from a rotor hub each having an airfoil mounted to a blade platform. The method includes adding or removing material from bladed rotor projections to alter the mass of the rotor and change the frequency of the respective airfoil.

Claims

1. A bladed rotor for a gas turbine engine, the bladed rotor comprising a hub and a circumferential array of blades extending from the hub;

each blade having an airfoil extending from a gaspath side of a platform provided at a periphery of the hub;

a first annular array of projections depending from an interior side of the platform, and a second annular array of projections depending from the interior side of the platform at circumferential locations corresponding to every N number of blades, N being an integer greater than one, each projection of the second annular array of projections being in line with a corresponding one of the blades, the second annular array of projections disposed downstream of the first annular array of projections, the second annular array of projections forming a circumferentially interrupted rib of projections circumferentially-spaced apart by voids, each void extending between adjacent projections and the interior side of the platform to form adjacent projections free of any linking structure, the circumferentially interrupted rib configured to provide a desired frequency response to the bladed rotor, wherein the second annular array of projections is disposed immediately downstream of the first annular array of projections, the first and second annular arrays of projections being located at either one of a trailing edge or a leading edge of the platform.

2. The bladed rotor defined in claim 1, wherein the second annular array of projections extends radially inwardly from the interior side of the platform.

3. The bladed rotor defined in claim 2, wherein the second annular array of projections is located at a leading edge of the platform.

4. The bladed rotor defined in claim 2, wherein the second annular array of projections is located at a trailing edge of the rotor.

5. The bladed rotor defined in claim 1, wherein the projections of the second annular array of projections are substantially identical in terms of shape and mass.

6. The bladed rotor defined in claim 1, wherein the bladed rotor is an integrally bladed rotor, the second annular array of projections being integral to the platform.

7. A method of tuning a bladed rotor in a gas turbine engine, wherein the bladed rotor includes a circumferential array of blades extending from a rotor hub, each blade having an airfoil extending from a blade platform, and a first annular array of projections depending from the blade platform;

the method comprising;

providing a second annular array of projections depending from the blade platform at circumferential locations corresponding to every second blade, each projection of the second annular array of projections being in line with an associated one of the blades, the second annular array of projections forming a circumferentially interrupted rib on the hub, wherein the second annular array of projections is disposed immediately downstream of the first annular array of projections, the first and second annular arrays of projections being located at either one of a trailing edge or a leading edge of the platform and tuning the bladed rotor by adding or removing mass to or from at least one of the projections of the second annular array of projections to achieve mistuned blade frequencies for the bladed rotor so that adjacent blades have different natural frequencies.

8. The method defined in claim 7, wherein the projections of the second annular array of projections have substantially identical shape and mass in an as-provided condition.

9. The method defined in claim 7, wherein tuning comprises removing or adding sufficient mass to change a frequency of at least one airfoil relative to a frequency of adjacent airfoils.

10. The method defined in claim 7, wherein tuning the bladed rotor comprises mistuning at least one blade so that adjacent blades have different natural frequencies.

11. A method of tuning a bladed rotor for a gas turbine engine, the bladed rotor including a rotor hub having a circumferential array of airfoil blades extending therefrom, the rotor hub having a gas path side defining a portion of a gas path in which the bladed rotor is to be mounted and an interior side opposite the gas path side, and first annular array of projections depending from the interior side of the rotor hub;

the method comprising;

providing a second annular array of projections depending from the interior side of the rotor hub, each projection of the second annular array of projections being in line with a corresponding one of the airfoil blades, wherein the second annular array of projections is disposed immediately downstream of the first annular array of projections, the first and second annular arrays of projections being located at either one of a trailing edge or a leading edge of the rotor hub, determining a frequency response of the bladed rotor in an as-manufactured condition, determining a desired frequency response, and then modifying the at least one projection to provide the bladed rotor with the desired frequency response and achieve mistuned blade frequencies between the airfoil blades of the bladed rotor.