Jet noise control system

Claim 2

A jet noise control system comprising: a nozzle adapted to receive the exhaust gas emitted through a tailpipe from the turbine of a jet engine and discharge it rearwardly in an expanding jetstream; and multiple duct means associated with the nozzle and constructed and arranged in surrounding relation thereto and in gas-receiving relation to the tailpipe to receive boundary layer gas therefrom and direct the same in a multiplicity of small jets of gas rearwardly of the nozzle to intercept the boundary of the jetstream at a multiplicity of loci around the periphery of the jetstream and immediately downstream of the exit margin of the nozzle to create turbulence in the jetstream boundary in the form of small eddies of high noise frequency level.

Claim 3

A system as claimed in claim 1; including means to supply bleed gas from the engine to constitute the source of said small jets of gas.

Claim 4

A system claimed in claim 2; said bleed gas being bleed exhaust gas from the turbine of the jet engine.

Claim 5

A system as claimed in claim 2; said bleed gas being bleed air from the compressor of the jet engine.

Claim 6

A system as claimed in claim 1; including means to discharge said jets of gas rearwardly at a velocity intermediate between the velocity of the jetstream and the velocity of the free airstream.

Claim 7

A system as claimed in claim 1; said means for directing radially jets comprising a multiplicity of jet nozzle ducts located around the periphery of the Outer wall ring the jets adjacent the exit margin thereof; each duct being generally parallel to the adjacent duct and arranged to discharge rearwardly along an interception course with a portion of the jetstream boundary.

Claim 8

A system as claimed in claim 6; said ducts being arranged to form a rearwardly converging frustum.

Claim 9

A system as claimed in claim 6; said ducts being spaced radially outward of the inner wall of the nozzle to define an initial mixing zone surrounded by a ring of jets issuing from said ducts.

Claim 10

A system as claimed in claim 6; the discharge area of each duct being not more than about 1 percent of the discharge area of the nozzle.

Claim 11

A system as claimed in claim 6; the discharge area of each duct being in the range of 0.1 percent to 1.0 percent of the discharge area of the nozzle. 1 A jet noise control system comprising: a nozzle adapted to receive the exhaust gas emitted by the turbine of a jet engine and discharge it rearwardly in an expanding jetstream; means associated with the nozzle and constructed and arranged to direct a multiplicity of small jets of gas rearwardly to intercept the boundary of the jetstream at a multiplicity of loci around the intercept the boundary of the jetstream at a multiplicity of loci around the periphery of the jetstream and immediately downstream of the exit margin of the nozzle to create turbulence in the jetstream boundary in the form of small size eddies of high noise frequency level, said means for directing said jets comprising a multiplicity of jets discharge ducts located around the periphery of the outer wall of the nozzle adjacent the exit margin thereof; each duct being generally parallel to the adjacent duct and arranged to discharge rearwardly along an interception course with a portion of the jet stream boundary, a tailpipe extending forwardly from the forward end of the nozzle; an means to bleed boundary layer gas from the tailpipe at the juncture of the tailpipe and the forward end of the nozzle and deliver it to said ducts for discharge therefrom.

Claim 12

A system as claimed in claim 11, said ducts being arranged so that said jets are discharged in concentric sets.

Claim 13

A system as claimed in claim 12 wherein the jets in at least one of said sets have a velocity different from that of the jets in another of said sets.

Claim 14

A jet noise control system comprising: a nozzle adapted to receive the exhaust gas emitted by the turbine of jet engine and discharge it rearwardly in an expanding jetstream; means associated with the nozzle and constructed and arranged to direct a multiplicity of small jets of gas rearwardly to intercept the boundary of the jetstream at a multiplicity of loci around the periphery of the jetstream and immediately downstream of the exit margin of the nozzle to create turbulence in the jetstream boundary in the form of small size eddies of high noise frequency level, said means for directing said jets comprising a multiplicity of jet discharge ducts located around the periphery of the outer wall of the nozzle adjacent the exit margin thereof; each duct being generally parallel to the adjacent duct and arranged to discharge rearwardly along an interception course with a portion of the jetstream boundary, a tailpipe extending forwardly from the forward end of the nozzle, a shell surrounding the outer wall of the nozzle in spaced relation to form a conduit connected at its aft end to said ducts; and passage means at the juncture of the tailpipe and the forward end of the nozzle in flow communication with the interior of said shell to supply gas for discharge from said ducts.

Claim 15

A jet noise control system comprising: a nozzle adapted to receive the exhaust gas emitted by the turbine of jet engine and discharge it rearwardly in an expanding jetstream; means associated with the nozzle and constructed and arranged to direct a multiplicity of small jets of gas rearwardly to intercept the boundary of the jetstream at a multiplicity of loci around the periphery of the jetstream and immediately downstream of the exit margin of the nozzle to create turbulence in the jetstream boundary in the form of small size eddies of high noise frequency level, said means for directing said jets comprising a multiplicity of jet discharge ducts located around the periphery of the outer wall of the nozzle adjacent the exit margin thereof; each duct being generally parallel to the adjacent duct and arranged to discharge rearwardly along an interception course with a portion of the jetstream boundary, a tailpipe extending forwardly from the forward end of the nozzle, a shell surrounding the outer wall of the nozzle in spaced relation to form a conduit connected at its aft end to said ducts; and passage means at the juncture of the tailpipe and the forward end of the nozzle in flow communication with the interior of said shell to supply gas for discharge from said ducts.

Claim 16

A system as claimed in claim 14; the aft end of said shell being corrugated with the troughs of the corrugations in engagement with the outer wall of the nozzle to form said ducts.

Claim 17

A system as claimed in claim 15; including a sleeve fixed in position around said shell and a second corrugated shell fixed in position around said sleeve, the troughs of the corrugatIons of said second shell contacting said sleeve to form second set of ducts concentrically disposed around the ducts formed by the corrugations of the inner shell, and passage means at the juncture of the tailpipe nd the forward end of the nozzle in flow communication with the ducts of said second set.

Claim 18

A system as claimed in claim 12; said shell being formed as continuation of said tailpipe; and the forward end of said nozzle being spaced inwardly from the forward end of said shell to define an annular passage for the flow of gas from said tailpipe to the interior of said shell.