Blunted leading edge fan blade for noise reduction

• US 3,883,268 A
• Filed: 08/29/1973
• Issued: 05/13/1975
• Est. Priority Date: 11/01/1971
• Status: Expired due to Term

• Current Assignee: Donald K. Dunbar, Robert C. Evans
• Original Assignee: Donald K. Dunbar, Robert C. Evans
• Inventors: Evans, Robert C., Dunbar, Donald K.
• Primary Examiner(s): Powell, Jr., Everette A.
• Application Number:
  US05/392,508
• Time in Patent Office: 622 Days
• Field of Search: 416/223,228 415/119
• US Class Current: 416/223.00R
• CPC Class Codes: F01D 5/12 Blades specially adapted for radial flow machines or engines F01D5/04; blade roots F01D5/30; rotors with blades adjustable in operation F01D7/00; stator blades F01D9/02
• CPC Class Codes: F02C 7/045 having provisions for noise suppression
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft

Abstract

A blade of a turbomachinery rotor stage includes a leading edge with a blunted contour over at least a portion of the radial length thereof. The blunting is accomplished in a variety of ways, such as by removing material from a portion of the leading edge, by blowing air into the leading edge or by positioning a mechanical device such as an inflatable boot around a portion of the leading edge. The aerodynamic or mechanical blunting can be utilized during selective portions of flight, such as take-off and landing. The blunting of leading edges of each of a plurality of blades in this way provides significant reduction in noise generated during rotation of the associated turbomachinery rotor state.

Claims

1. In a gas turbine engine of the type which includes rotating turbomachinery, a combustion section, and an exhaust nozzle adapted to provide a propulsive force, the improvement comprising:

a rotatable disc; and

a plurality of turbomachinery rotor blades carried by said disc and having leading edges at least a portion of which include blunting means for reducing the noise generated by the rotation of said blade, and wherein said leading edges of said blades are generally coplanar.

2. The improvement of claim 1 wherein said blunting means comprises a flattened leading edge which extends over at least a portion of the length of each of said blades.

3. The improvement of claim 2 wherein said flattened leading edge extends along approximately the outer one-third of the blade height.

4. The improved turbomachinery rotor blade recited in claim 1 wherein said blade comprises a fan blade of a turbofan engine.

5. The improvement of claim 2 wherein said flattened leading edge is more blunt than that of an aerodynamically ideal blade in a selected application.