Turbomachine nozzle with noise reduction
View Patent ↗A nozzle comprising an inner barrel, a centerbody disposed inside the inner barrel so as to define a first channel for a primary flow, and an outer barrel surrounding the inner barrel so as to define a second annular channel for a secondary flow, the free end of the inner barrel presenting a surface having a first series of undulations made up of negative undulations alternating with positive undulations, the centerbody presenting a second series of undulations made up of negative undulations alternating with positive undulations, the negative and positive undulations of the series of undulations being of radial height that varies angularly and being disposed in such a manner that the negative undulations of the first series are disposed facing negative undulations of the second series, and vice versa, so as to generate turbulence and radial shear between the primary and secondary flows while conserving a constant flow section around the entire circumference of the nozzle.
1. A turbomachine nozzle comprising:
a substantially cylindrical inner barrel extending along a longitudinal axis of said nozzle;
a centerbody disposed concentrically inside said inner barrel and extending beyond a free end of said inner barrel in the form of a substantially conical portion so as to define between said inner barrel and said centerbody a first annular channel for receiving a primary flow having a cross-section that is substantially constant around the entire circumference of said nozzle; and
an outer barrel concentrically surrounding said inner barrel so as to define a second annular channel for a secondary flow;
said free end of the inner barrel presenting a surface having a first series of undulations regularly distributed around said longitudinal axis of the nozzle, said first series of undulations being formed by negative undulations which extend radially inwards relative to said inner barrel, alternating with positive undulations which extend radially outwards relative to said inner barrel;
wherein said centerbody presents a second series of undulations at least in a portion facing said undulating surface at the free end of the inner barrel, said second series of undulations being regularly distributed around said longitudinal axis of the nozzle, said second series of undulations being made up of negative undulations extending radially inwards relative to said centerbody, alternating with positive undulations extending radially outwards relative to said centerbody, said negative and positive undulations of said first and second series of undulations being of radial height that varies angularly and being disposed in such a manner that the negative undulations of said first series of undulations are disposed facing negative undulations of said second series of undulations, and vice versa, so as to generate turbulence and radial shear between said primary and secondary flows downstream from said first and second series of undulations, while conserving a constant flow section around the entire circumference of said nozzle.
2. A nozzle according to claim 1 , wherein the undulating surface of the centerbody extends longitudinally over the entire conical portion of said centerbody.
3. A nozzle according to claim 1 , wherein the undulating surface of the centerbody extends longitudinally over part of the conical portion of said centerbody.
4. A nozzle according to claim 3 , wherein a non-undulating surface of the conical portion of the centerbody includes a plurality of substantially rectangular arms enabling the amplitude of the radial shear between said primary and secondary flows to be increased, said arms extending longitudinally beyond a free end of said conical portion of the centerbody in the length direction thereof and radially in the width direction thereof, the arms intersecting on said longitudinal axis of the nozzle.
5. A nozzle according to claim 4 , wherein said arms are of the same length and of the same width, and are symmetrical about the longitudinal axis of said nozzle.
6. A nozzle according to claim 4 , wherein said arms are disposed in line with negative undulations of the second series of undulations.
7. A nozzle according to claim 4 , wherein said arms present means at a free end for generating additional radial shear between said primary and secondary flows.
8. A nozzle according to claim 7 , wherein said additional shear means are longitudinal slots forming an angle relative to the longitudinal axis of said nozzle and facing downstream therefrom.
9. A nozzle according to claim 8 , wherein each of said arms presents at least four slots disposed in pairs symmetrically about the longitudinal axis of said nozzle, the slots further from said longitudinal axis forming an angle relative thereto that is greater than the angle formed by the slots closer to said longitudinal axis of the nozzle.
10. A nozzle according to claim 7 , wherein said additional shear means are longitudinal fins disposed perpendicularly to the arms.
11. A nozzle according to claim 10 , wherein each of said arms presents at least two fins disposed symmetrically about the longitudinal axis of said nozzle.
12. A nozzle according to claim 4 , wherein said arms present at least one angular twist relative to said longitudinal axis of the nozzle so as to generate swirling in the primary flow.
13. A nozzle according to claim 1 , wherein said free end of the inner barrel includes a series of tongues downstream from said first series of undulations, said tongues enabling the amplitude of the radial shear between said primary and secondary flows to be increased, said series of tongues being made up of negative tongues disposed in line with negative undulations of said first series of undulations, alternating with positive tongues disposed in line with positive undulations of said first series of undulations.
14. A nozzle according to claim 13 , wherein the free ends of said negative and positive tongues are rounded so as to form U-shapes.
15. A nozzle according to claim 13 , wherein the free ends of said negative and positive tongues are pointed so as to form V-shapes.
16. A nozzle according to claim 1 , wherein the undulations of said second series of undulations presents angular twist relative to said longitudinal axis of the nozzle so as to generate swirling in the primary flow.
17. A nozzle according to claim 16 , wherein the undulations of said first series of undulations present angular twisting equivalent to that of the undulations of said second series of undulations relative to said longitudinal axis of the nozzle.
18. A nozzle according to claim 1 , wherein each of the negative and positive undulations of the first series of undulations include at least one notch or at least one deflector fin forming an angle relative to the longitudinal axis of said nozzle so as to generate swirling in the primary and secondary flows.
19. A nozzle according to claim 1 , wherein each of said first and second series of undulations is formed by eight negative undulations alternating with eight positive undulations.