Aircraft gas turbine noise suppression

• US 3,927,522 A
• Filed: 12/17/1973
• Issued: 12/23/1975
• Est. Priority Date: 12/18/1972
• Status: Expired due to Term

• Current Assignee: Brian Arthur Turner, Richard Alfred Pinker, William Dean Bryce
• Original Assignee: Brian Arthur Turner, Richard Alfred Pinker, William Dean Bryce
• Inventors: Bryce, William Dean, Pinker, Richard Alfred, Turner, Brian Arthur
• Primary Examiner(s): Husar, C. J.
• Assistant Examiner(s): Ross, Thomas I.
• Application Number:
  US05/425,235
• Time in Patent Office: 736 Days
• Field of Search: 239/127.3,265.13 181/33HB,33HC,33HD 60/232,264,271
• US Class Current: 60/264
• CPC Class Codes: F02K 1/38 Introducing air inside the jet F02K1/28 takes precedence
• CPC Class Codes: F02K 1/48 Corrugated nozzles
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft

Abstract

In an aircraft gas turbine installation having a jet pipe which extends downstream of the turbine by a distance at least equal to the jet pipe nozzle diameter, a plurality of moveable members are mounted in the jet pipe. The members usually lie parallel to the centerline of gas flow through the pipe but, when it is desired to suppress noise, can be moved into positions where they provide a serrated restriction to flow through the pipe. The members are preferably mounted on the jet pipe, to lie usually flush with the jet pipe. Alternatively the members may be mounted on struts connecting the jet pipe to a bullet downstream of the turbine.

Claims

1. A gas turbine engine comprising a turbine;

a jet pipe extending downstream of the turbine and terminating in a primary nozzle, conditions at which affect the operation and efficiency of the engine in normal flight conditions, the length of the jet pipe downstream of the turbine being at least equal to the primary nozzle diameter; and

a plurality of members adjacent the turbine upstream of said primary nozzle and moveable between positions corresponding to normal flight conditions where they lie parallel to the centerline of gas flow through the pipe and positions where they extend at an angle to the gas flow to form a serrated restriction to flow through the pipe, said members when not extended forming a secondary nozzle of larger area normal to flow therethrough than the area normal to flow through said primary nozzle and when extended forming a secondary nozzle of smaller area normal to flow therethrough than the area normal to flow through said primary nozzle so that conditions at the secondary nozzle and not conditions at the primary nozzle affect the operation and efficiency of the engine and so that the gas flow through the secondary nozzle is substantially divided into a plurality of separate flow streams, the jet pipe downstream of the secondary nozzle becoming a shield for noise emanating from the secondary nozzle.

2. A gas turbine engine as claimed in claim 1 wherein said members are mounted on said jet pipe and are moveable between positions where they lie flush with said jet pipe and positions where they extend into the gas flow.

3. A gas turbine engine as claimed in claim 2 wherein the jet pipe is provideD with apertures through which external air may enter the jet pipe, said apertures being normally closed by said members and being opened when said members are moved to positions where they extend at an angle to the gas flow through the pipe.

4. A gas turbine engine as claimed in claim 1 further comprising a bullet downstream of said turbine and struts connecting the bullet to said jet pipe, said members being mounted on said struts.