Device for attaching a flame-holder arm to an afterburner housing
View Patent ↗A flame-holder device for an afterburner of a turbofan, the turbofan including a first inner annular casing and a second inner annular casing, these defining a passage for a primary flow, and an outer annular casing defining with the first inner annular casing a passage for a secondary flow, including at least one arm-support made of metallic material configured to be fixed to the outer casing by an upper plate and at least one flame-holder arm of a one-piece structure of composite material including two mutually attached walls arranged to define a groove whose profile is approximately a V. The walls support, on their upper part situated in the secondary flow, a fixing mechanism for fixing to the arm-support. The upper parts are approximately planar and are positioned facing each other.
1. A flame-holder device for an afterburner of a bypass turbojet, the turbojet including a first inner annular housing and a second inner annular housing, defining a passageway for a main flow, and an outer annular housing defining with the first inner annular housing a passageway for a bypass flow, the device comprising:
at least one arm support made of metal and configured to be attached to the outer housing by an upper plate; and
at least one flame-holder arm of a one-piece structure made of composite material including two joined-together walls arranged to define a throat having a substantially V-shaped profile, the walls supporting on their top portions situated in the bypass flow an attachment device which attaches the flame-holder arm to the arm support,
wherein the top portions are flat and positioned facing one another,
wherein the arm support includes two lateral struts of which on an inside each includes a hollow cavity which leads, in a direction of the outer housing, into a top cavity hollowed out of the upper plate, and
wherein the flame-holder device further comprises at least one pressure-tapping hole pierced in a bottom portion of each of the struts to feed air to the hollow and the top cavities, an orifice for letting the air out being arranged in the top portion of the device at the outer housing.
2. A flame-holder device for an afterburner according to claim 1 , wherein the attachment device includes bolts interfacing with the pierced holes made in the top portions, elastic washers being positioned between a head of the bolts and bearing faces via which the heads bear on the top portions, so as to maintain tightness despite differences in expansion of the composite material and of the metal.
3. A flame-holder device for an afterburner according to claim 2 , further comprising bosses so that the bolts for attaching the arm to the arm support pass in a sealed manner through the cavities in the struts.
4. A flame-holder device for an afterburner according to claim 3 , wherein the bosses are oblong so as to have sufficient material to allow counterbores in the struts facing the pierced holes made in the top portions of the arm.
5. A flame-holder device for an afterburner according to claim 1 , further comprising pressure-tapping holes fitted with a ring configured to seal the air passageway between the outside of the flame-holder arm and the arm support.
6. A flame-holder device for an afterburner according to claim 1 , wherein the top portions of the walls include a hole positioned, after assembly, facing the pressure-tapping holes pierced in the bottom portion of the struts.
7. A flame-holder device for an afterburner according to claim 1 , wherein the upper plate includes a pierced hole for the passage of a fuel injector.
8. A flame-holder device for an afterburner according to claim 7 , wherein the injector is attached to the outer housing and guided in a bottom portion by a guide shoe attached to a ventilation tube, the ventilation tube being connected at the top portion by a swivelling connection at the arm support.
9. A flame-holder device for an afterburner according to claim 1 , wherein the arm support includes an intermediate plate and a bottom plate both configured to support a spray ring of the afterburner system.
10. A flame-holder device for an afterburner according to claim 9 , wherein the bottom plate supports the inner face of the spray ring by bearing faces with an overall surface area less than 25% of an overall surface area of the bottom plate.
11. A flame-holder device for an afterburner according to claim 9 , wherein the bottom plate includes a passageway hole for an injector and a cylindrical passageway hole defining a swivel connection between the ventilation tube and the arm support.
12. A flame-holder device for an afterburner according to claim 1 , wherein the lateral struts and the top portions diverge from one another relative to a plane of symmetry of the arm support.
13. A flame-holder device for an afterburner according to claim 12 , wherein the angle of divergence relative to the plane of symmetry of the arm support is less than 7°.
14. An afterbody of a bypass turbojet with afterburner, comprising a flame-holder device according to claim 1 .
15. A bypass turbojet with afterburner comprising an afterbody according to claim 14 .