SOUND-SUPPRESSING AND THRUST-REVERSING APPARATUS

• US 3,568,792 A
• Filed: 06/18/1969
• Issued: 03/09/1971
• Est. Priority Date: 06/18/1969
• Status: Expired due to Term

• Current Assignee: Rohr Industries, Inc. (Rtx Corporation)
• Original Assignee: George R. Urquhart
• Inventors: Urquhart, George R.
• Application Number:
  US04/834,343
• Time in Patent Office: 629 Days
• US Class Current: 181/215
• CPC Class Codes: F02K 1/383 with retractable elements
• CPC Class Codes: F02K 1/46 Nozzles having means for adding air to the jet or for augmenting the mixing region between the jet and the ambient air, e.g. for silencing F02K1/28, F02K1/36, F02K1/38 take precedence
• CPC Class Codes: F02K 1/48 Corrugated nozzles
• CPC Class Codes: F02K 1/60 by blocking the rearward discharge by means of pivoted eyelids or clamshells, e.g. target-type reversers

Abstract

Apparatus includes exhaust gas nozzle and at least two deflectors of arcuate cross section generally surrounding nozzle. Trailing edges of deflectors are serrated to form spikes. In first, retracted position, deflectors are streamlined with nacelle. In second position, leading edges of deflectors scoop in ambient air around nozzle and some spikes overlie nozzle exit to turbulize gas stream, while others intercept ambient air, causing mixing and cooling and noise reduction. In third, fully extended position deflectors join to produce reverse thrust bucket, and spikes are offset laterally to mesh and permit tight closing. Nozzle may be daisy type to also produce noise suppression.

Claims

1. Sound-suppressing and thrust-reversing apparatus for use with a jet engine mounted in a nacelle, comprising:

an exhaust nozzle located at the aft end of the nacelle and adapted to receive a high-velocity exhaust gas stream from the engine and discharge it rearwardly;

at least two oppositely disposed deflectors movably mounted on the nacelle;

said deflectors having leading and trailing edges and being generally arcuate in cross section transversely of the axis of the nozzle and adapted in a first, retracted position to surround a major portion of the nozzle;

the trailing edge of each deflector being serrated to form a plurality of rearwardly directed spikes; and

actuator means adapted to move said deflectors to a second, extended position in which their leading edges extend into the slipstream to serve as scoops and direct ambient air inwardly over the exterior of the nozzle, and at least some of the spikes extend into the exhaust gas stream to cause turbulence in the flow and at least partially suppress the exhaust noise.

2. Apparatus as claimed in claim 1;

at least some of the spikes intercepting the ambient air directed over the nozzle by the deflector leading edges to cause turbulence therein and mixing of the ambient air with the exhaust gas stream to further suppress the exhaust noise.

3. Apparatus as claimed in claim 1;

said nozzle being longitudinally corrugated to form a plurality of angularly spaced radially extending lobes to divide the exhaust stream into a plurality of separate jet streams with ambient air flowing between them;

some of the spikes in the second position overlying the outer portions of some of the lobes ad some of the spikes in the second position overlying the spaces between the lobes to produce turbulence in both the jet streams and the ambient airflow and produce maximum mixing and cooling for maximum sound suppression.

4. Apparatus as claimed in claim 1;

said actuator means being further adapted to move said deflectors to a third, fully extended position rearward of the nozzle with their trailing edges in juxtaposition and their leading edges located laterally and forwardly of their trailing edges to intercept the exhaust gas flow and direct it laterally and forwardly to produce a reverse thrust.

5. Apparatus as claimed in claim 4;

the spikes on one deflector being offset laterally with respect to the spikes on the other to facilitate meshing with each other and provide a substantially sealed closure engagement between the trailing edges of the deflectors.

6. Apparatus as claimed in claim 5;

the base of each spike at the trailing edge of each deflector being spaced from the base of each adjacent spike by a distance sufficient to accommodate the base of a meshing spike on the opposed deflector.

7. Sound suppressing apparatus for use with a jet engine mounted in a nacelle, comprising:

an exhaust nozzle located at the aft end of the nacelle and adapted to receive a high velocity exhaust gas stream from the engine and discharge it rearwardly; and

turbulence producing means movably mounted on said nacelle and comprising a plurality of slender elongate members in the general form of spikes arranged generally parallel to each other and laterally spaced;

said spikes being movable from a first retracted position externaL to the exhaust gas stream to a second position behind the nozzle and protruding at least partially into the exhaust gas stream to intercept the gas and cause local turbulence and reduce the jet noise.

8. Apparatus as claimed in claim 7;

including means to introduce ambient air from the exterior of the nacelle to flow rearwardly over the nozzle; and

additional spikes movable into position to intercept the airflow and cause turbulence therein and mixing of the air with the exhaust gas stream to further reduce the jet noise.

9. Apparatus as claimed in claim 8;

said means to introduce ambient air comprising scoop means movable laterally of the nacelle into the ambient airstream to receive the air under ram pressure for forceful delivery over the nozzle.

10. Apparatus as claimed in claim 9;

said spikes being carried by said scoop means and being adapted to move rearwardly and inwardly as said scoop means move laterally outwardly.

11. Apparatus as claimed in claim 7;

said nozzle being formed to divide the exhaust stream into separate jet streams to further reduce the jet noise.

12. The method of suppressing jet engine noise on an aircraft having a pair of deflector doors movable from a stowed position on opposite sides of the engine nozzle to a deployed thrust reverser position downstream of the nozzle, comprising the steps of moving the deflector doors into an intermediate ejector position for entraining a mass of the surrounding air for mixing with the jet gases issuing from the nozzle thereby to effect a first order of sound suppression, and dividing the entrained air and the gases mixed therewith at the downstream ends of the deflectors to raise the frequency of the accompanying noise thereby to effect a second order of sound suppression.

13. The method as in claim 12 wherein the nozzle is corrugated to divide the jet stream issuing internally therefrom thereby to further suppress the noise accompanying the jet stream and wherein the ejector airstream issuing externally over the corrugated nozzle is constrained to flow in the external trough passages thereof thereby to reduce the base drag due to low pressures in said exterior passages.