Gas turbine engine with short inlet and mistuned fan blades

Patent metadata

Field	Value
Publication number	US-10823192-B2
Application number	US-201514974151-A
Country	US
Kind code	B2
Filing date	Dec 18, 2015
Priority date	Dec 18, 2015
Publication date	Nov 3, 2020
Grant date	Nov 3, 2020

Abstract

A gas turbine engine comprises a fan rotor having fan blades received within an outer nacelle. The fan blades are provided with at least a first type having a first natural frequency, and a second type having a second natural frequency. The fan rotor has a first mount structure intended for the first type and a distinct second mount structure intended for the second type. The first type of fan blade fits into the first mount structure intended for the first type, but there is a first obstruction preventing the first type of fan blade from being placed into the second mount structure intended for the second type. The second type of fan blade fits into the second mount structure intended for the second type, but there is a second obstruction preventing the second type of fan blade from being placed into the first mount structure intended for the first type.

First claim

The invention claimed is:

1. A gas turbine engine comprising:
a fan rotor having fan blades received within an outer nacelle; and
said fan blades being provided with at least a first type having a first natural frequency, and a second type having a second natural frequency and said fan rotor having a first mount structure intended for said first type and a distinct second mount structure intended for said second type, and said first type of fan blade fitting into the first mount structure intended for said first type, but there being a first obstruction preventing said first type of fan blade from being placed into the second mount structure intended for said second type, and said second type of fan blade fitting into the second mount structure intended for said second type, but there being a second obstruction preventing said second type of fan blade from being placed into the first mount structure intended for said first type; and
wherein a distance is defined from a plane defined by leading edges of said fan blades to an axial location of a forwardmost part of said nacelle, and an outer diameter of said fan blades being defined, and a ratio of said distance to said outer diameter is between 0.2 and 0.5.

2. The gas turbine engine as set forth in claim 1 , wherein said nacelle is formed with droop such that one portion extends axially farther from said fan blades than does another portion, said one portion being said forwardmost part, and wherein said distance measured to the one portion of said nacelle will still result in a ratio less than 0.45, and a second distance being measured to the another portion of said nacelle still results in said ratio being greater than 0.20.

3. The gas turbine engine as set forth in claim 1 , wherein said ratio being greater than or equal 0.25.

4. The gas turbine engine as set forth in claim 3 , wherein said ratio being greater than or equal to 0.30.

5. The gas turbine engine as set forth in claim 1 , wherein said ratio being less than or equal to 0.40.

6. The gas turbine engine as set forth in claim 1 , wherein a fan drive turbine driving said fan rotor through a gear reduction.

7. The gas turbine engine as set forth in claim 6 , wherein a gear ratio of said gear reduction being greater than 2.3.

8. The gas turbine engine as set forth in claim 1 , wherein a first flange is received in first slots formed in one of said fan rotor and said first type of fan blades, and the other of said rotor and said first type of blades is formed with a first groove to receive said first flange.

9. The gas turbine engine as set forth in claim 8 , wherein a second flange is received in second slots formed in one of said fan rotor and said second type of fan blades, and the other of said fan rotor and said second type of blades is formed with a second groove to receive said second flange.

10. The gas turbine engine as set forth in claim 9 , wherein said first groove and said first flange for said first type of fan blade, and said second groove and said second flange for said second type of fan blade are at distinct locations.

11. The gas turbine engine as set forth in claim 9 , wherein said first flange and said second flange are formed in said fan rotor.

12. The gas turbine engine as set forth in claim 9 , wherein said first flange and said second flange are formed, respectively, on said first type of fan blades and said second type of fan blades.

13. The gas turbine engine as set forth in claim 1 , wherein said first and second types of fan blades each has a dovetail with circumferential sides, and said circumferential sides being formed differently for each of said first and second type of fan blades, wherein an angle of at least one of said circumferential sides is different among said first type of fan blade and second type of fan blade.

14. The gas turbine engine as set forth in claim 1 , wherein said first and second types of fan blades each has a dovetail with circumferential sides, and said circumferential sides being formed differently for each of said first and second type of fan blades, wherein said circumferential sides of said first type of fan blades and said second type of fan blades have a radially higher circumferential side and a radially lower circumferential side, and the higher and lower circumferential sides are reversed among said first type of fan blades and second type of fan blades.

15. The gas turbine engine as set forth in claim 1 , wherein said first natural frequency has a blade-only structural mode and said second natural frequency has a blade-only structural mode, and a difference between a lowest two blade-only structural modes of said first and second natural frequencies being at least 2%.

16. A gas turbine engine comprising: a fan rotor having fan blades received within an outer nacelle; said fan blades being provided with at least a first type having a first natural frequency having blade-only structural modes, and a second type having a second natural frequency having blade-only structural modes, and said fan rotor having a first mount structure intended for said first type and a distinct second mount structure intended for said second type, and said first type of fan blade fitting into the first mount structure intended for said first type, but there being a first obstruction preventing said first type of fan blade from being placed into the second mount structure intended for said second type, and said second type of fan blade fitting into the second mount structure intended for said second type, but there being a second obstruction preventing said second type of fan blade from being placed into the first mount structure intended for said first type; and wherein a difference between a lowest two blade-only structural modes of said first and second natural frequencies being at least 2%.

Assignees

• United Technologies Corp
• Raytheon Tech Corp

Inventors

• Schwarz Frederick M
• Gysling Daniel L

Classifications

• F01D5/027 Primary

  Arrangements for balancing (for balancing rotating bodies in general F16F15/32; for compensating imbalance G01M1/36) · CPC title

• F01D5/10

  Anti- vibration means {(specially adapted for radial flow machines or engines F01D5/04)} · CPC title

• F04D29/666

  by means of rotor construction or layout, e.g. unequal distribution of blades or vanes · CPC title

• F05D2250/73

  asymmetric · CPC title

• F01D5/3007

  of axial insertion type · CPC title