Fan rotor with flow induced resonance control

Patent metadata

Field	Value
Publication number	US-10823203-B2
Application number	US-201715465825-A
Country	US
Kind code	B2
Filing date	Mar 22, 2017
Priority date	Mar 22, 2017
Publication date	Nov 3, 2020
Grant date	Nov 3, 2020

Abstract

A rotor for a gas turbine is disclosed which includes alternating first and second set of rotor blades, the first set of rotor blades having a baseline profile and the second set of rotor blades having a profile with a cutback relative to the baseline profile, the cutback removing a portion of the baseline profile surrounding a maximum deflection point of a selected natural vibration mode. The cutback may be a tip trailing edge cutback at a span position located a distance away from the hub of at least 75% of the total span length. The selected natural vibration mode may be a natural vibration mode higher than the 1 st natural vibration mode, more specifically may be the 3 rd or 6 th natural vibration mode.

First claim

The invention claimed is:

1. A fan for a gas turbine, the fan comprising fan blades circumferentially distributed around and extending a full span length from a central hub, the fan blades including alternating first fan blades and second fan blades, the first fan blades having a baseline profile and the second fan blades having a modified profile being the same as the baseline profile but for a trailing edge cutback, the trailing edge cutback extending from a tip position to a second span position, wherein the tip position corresponding to a maximum deflection point for a selected natural vibration mode of at least one of the first fan blades having the baseline profile and wherein the second span position is located radially inwardly of the maximum deflection point, the trailing edge cutback removing a portion of the baseline profile surrounding the maximum deflection point and all points of at least 95% of maximum deflection of the selected natural vibration mode.

2. The fan as defined in claim 1 , wherein the second span position is located at a distance away from the hub exceeding 75% of the total span length.

3. The fan as defined in claim 2 , wherein the second span position is located at a distance away from the hub exceeding 90% of the total span length.

4. The fan as defined in claim 1 , wherein the trailing edge cutback removes a portion of the baseline profile surrounding the maximum deflection point and all points of no less than 65% of maximum deflection of the selected natural vibration mode.

5. The fan as defined in claim 1 , wherein the selected natural vibration mode is a natural vibration mode higher than the 1 st natural vibration mode.

6. The fan as defined in claim 1 , wherein the selected natural vibration mode is the 3 rd natural vibration mode.

7. The fan as defined in claim 1 , wherein the selected natural vibration mode is the 6 th natural vibration mode.

8. The fan as defined in claim 1 , wherein the fan blades are swept fan blades.

9. The fan as defined in claim 1 , wherein the fan blades include third fan blades, the third fan blades successively alternating with the first fan blades and the second fan blades, the third fan blades having a second modified profile, the second modified profile being the same as the baseline profile but for a cutback different from the trailing edge cutback of the modified profile of the second fan blades.

10. A rotor for a gas turbine, the rotor comprising rotor blades circumferentially distributed around and extending a total span length from a central hub, the rotor blades including alternating first and second rotor blades, the first rotor blades having a baseline profile and the second rotor blades having a profile with a tip trailing edge cutback relative to the baseline profile, the tip trailing edge cutback extending from a tip position to a second span position, wherein the second span position is located at a distance away from the hub exceeding 75% of the total span length, the tip position corresponding to a maximum deflection point for a selected natural vibration mode of the first fan blades, and the second span position located radially inwardly of the maximum deflection point, the tip trailing edge cutback removing a portion of the baseline profile surrounding the maximum deflection point and all points of at least 95% of maximum deflection of the selected natural vibration mode.

11. The rotor as defined in claim 10 , wherein the selected natural vibration mode is a natural vibration mode higher than the 1 st natural vibration mode.

12. The rotor as defined in claim 11 , wherein the selected natural vibration mode is a 3 rd natural vibration mode.

13. The rotor as defined in claim 11 , wherein the selected natural vibration mode is a 6 th natural vibration mode.

14. A rotor for a gas turbine, the rotor comprising rotor blades circumferentially distributed around and extending a total span length from a central hub, the rotor blades including alternating first and second rotor blades, the first rotor blades having a baseline profile and the second rotor blades having a profile with a cutback relative to the baseline profile, the cutback removing a portion of the baseline profile surrounding a maximum deflection point of a selected natural vibration mode, the portion of the baseline profile removed by the cutback surrounding the maximum deflection point and all points of at least 95% of maximum deflection of the selected natural vibration mode.

15. The rotor of claim 14 , wherein the portion of the baseline profile removed by the cutback surrounds the maximum deflection point and all points of no less than 65% of maximum deflection of the selected natural vibration mode.

16. The rotor as defined in claim 14 , wherein the selected natural vibration mode is a natural vibration mode higher than the 1 st natural vibration mode.

17. The rotor as defined in claim 16 , wherein the selected natural vibration mode is a 3 rd natural vibration mode.

18. The rotor as defined in claim 16 , wherein the selected natural vibration mode is a 6 th natural vibration mode.

Assignees

• Pratt & Whitney Canada

Inventors

• Theratil Ignatius
• Balike Krishna

Classifications

• F01D5/141

  Shape, i.e. outer, aerodynamic form (F01D5/148 - F01D5/20 take precedence; blade construction F01D5/147) · CPC title

• Y02T50/60

  Efficient propulsion technologies, e.g. for aircraft · CPC title

• F05D2240/303

  related to the leading edge of a rotor blade · CPC title

• F05D2260/961

  by mistuning rotor blades or stator vanes with irregular interblade spacing, airfoil shape · CPC title

• F05D2230/10

  by removing material · CPC title