US4076455A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rotor blade system for a gas turbine engine
Assignee: RTX Corp
•
Filing: 1976-06-28
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Granted: 1978-02-28
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Expires: 1996-06-28
Abstract
Abstract A rotor blade system which is adapted for long term reliable operation in a gas turbine engine is disclosed. Techniques for altering the natural frequency of the blade system to reduce the detrimental combined effects of external excitation and self-excitation are developed. One structure shown utilizes a shroud for the control of self-excitation in combination with a pin root to lower the fundamental first natural bending frequency of the blade system below the level of the 2E frequency at idle.
Inventors
- 👤 Hans Stargardter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 13:12
CPC Classifications
F; F01; F01D; F01D5/00; F01D5/30; F01D5/3053; F01D5/12; F01D5/22; F01D5/225; Y; Y10; Y10S; Y10S416/00; Y10S416/50
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
114 words
In a gas turbine engine a rotor blade system which is adapted for reduced susceptibility to vibratory damage wherein said blade system comprises: a rotor disk; and a plurality of rotor blades cantilevered radially outward from the said disk wherein each blade is pivotally joined to the disk so as to be circumferentially deflectable under bending loads, and each blade has a shroud extending circumferentially from the airfoil surfaces of the blade into abutting relationship with the shrouds of the adjacent blades and wherein the natural bending frequency of each blade in the system is less than the 2E frequency at the idle condition of the engine in which the blade system is installed.
Claim 2
Dependent Claim
114 words
In a gas turbine engine a rotor blade system which is adapted for reduced susceptibility to vibratory damage wherein said blade system comprises: a rotor disk; and a plurality of rotor blades cantilevered radially outward from the said disk wherein each blade is pivotally joined to the disk so as to be circumferentially deflectable under bending loads, and each blade has a shroud extending circumferentially from the airfoil surfaces of the blade into abutting relationship with the shrouds of the adjacent blades and wherein the natural bending frequency of each blade in the system is less than the 2E frequency at the idle condition of the engine in which the blade system is installed.
Claim 3
Dependent Claim
39 words
The invention according to claim 1 wherein the natural bending frequency of said blade system is more than five percent less than the 2E frequency at the idle operating condition of the engine in which the rotor is installed.
Claim 4
Dependent Claim
20 words
The invention according to claim 1 wherein the shroud of each blade is positioned at the tip of the blade.
Claim 5
Dependent Claim
21 words
The invention according to claim 1 wherein the shroud of each blade is positioned at the midspan region of the blade.
Claim 6
Dependent Claim
25 words
The invention according to claim 1 wherein each blade is affixed to the rotor disk by a pin which penetrates the root of the blade.
Claim 7
Dependent Claim
39 words
The invention according to claim 5 wherein the natural bending frequency of said blade system is more than five percent less than the 2E frequency at the idle operating condition of the engine in which the rotor is installed.
Claim 8
Dependent Claim
20 words
The invention according to claim 5 wherein the shroud of each blade is positioned at the tip of the blade.
Claim 9
Dependent Claim
21 words
The invention according to claim 5 wherein the shroud of each blade is positioned at the midspan region of the blade.
Claim 10
Independent Claim
81 words
The method for reducing the susceptibility of a rotor blade of a gas turbine engine to vibratory damage, comprising the steps of: providing a blade natural bending frequency which is less than the 2E frequency at idle operating conditions of the engine in which the blade is installed; providing a pin root blade attachment to decrease the bending stresses in the root portion of the blade; and providing a blade shroud to reduce the self-excited torsional vibration of the blade system.
Claim 11
Independent Claim
81 words
The method for reducing the susceptibility of a rotor blade of a gas turbine engine to vibratory damage, comprising the steps of: providing a blade natural bending frequency which is less than the 2E frequency at idle operating conditions of the engine in which the blade is installed; providing a pin root blade attachment to decrease the bending stresses in the root portion of the blade; and providing a blade shroud to reduce the self-excited torsional vibration of the blade system.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-02-27 | 1981-08-29 | 1982-02-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-02-27 | 1985-08-29 | 1986-02-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-02-27 | 1989-08-29 | 1990-02-28 | $7700.00 | Window Closed / Lapsed |