Turbine engine acoustic panel with outer flange case mounting
A gas turbine engine includes a fan case assembly adapted to extend around blades of a fan rotor included in the gas turbine engine. The fan case assembly includes an annular case that extends around an axis, an acoustic panel coupled to the annular case and configured to dampen vibrations and a bolting arrangement that couples the acoustic panel to the annular case.
1. A fan case assembly adapted to extend around blades of a fan rotor included in a gas turbine engine, the fan case assembly comprising
an annular case that extends around an axis, the annular case having an inner radial surface and an outer radial surface opposite the inner radial surface and facing away from the axis,
an acoustic panel coupled to the annular case and configured to dampen vibrations, the acoustic panel extending circumferentially at least partway about the axis and including a panel body and a forward attachment flange, the panel body including an outer body section having a first axial length and an inner body section having a second axial length greater than the first axial length, the forward attachment flange extends axially away from the outer body section of the panel body to provide a radially intermediate surface between an outer surface of the outer body section and an inner surface of the inner body section and to form a cavity radially between the forward attachment flange and the inner body section of the panel body, and
a bolting arrangement that couples the acoustic panel to the annular case, the bolting arrangement including a first captured nut and a first attachment fastener, the first captured nut fixed to the radially intermediate surface of the forward attachment flange and located in the cavity, and the first attachment fastener extends radially through the outer radial surface of the annular case, the inner radial surface of the annular case, through the forward attachment flange, and mates with the first captured nut in the cavity to couple the acoustic panel with the annular case.
2. The fan case assembly of claim 1 , wherein the forward attachment flange has a first radial thickness and the inner body section has a second radial thickness greater than the first radial thickness.
3. The fan case assembly of claim 2 , wherein the outer body section has a third radial thickness greater than the first radial thickness and equal to or less than the second radial thickness.
4. The fan case assembly of claim 1 , wherein the first attachment fastener has a radially outer end positioned radially outward of the annular case and a radially inner end positioned in the cavity.
5. The fan case assembly of claim 4 , wherein the inner body section is formed without any attachment through holes such that no fasteners extend through the inner body section.
6. The fan case assembly of claim 5 , wherein outer body section is formed without any attachment through holes such that no fasteners extend into the outer body section.
7. The fan case assembly of claim 2 , wherein the cavity is formed in a forward end of the acoustic panel and opens in an axially-forward direction.
8. The fan case assembly of claim 1 , wherein the first captured nut is a riveted nutplate that is fixed to a radially inner surface of the forward attachment flange.
9. The fan case assembly of claim 1 , wherein the acoustic panel further includes an aft attachment flange coupled to an aft end of the outer body section and arranged to lie radially between the annular case and the inner body section, the aft attachment flange cooperating with the inner body section to define a second cavity radially between the aft attachment flange and the inner body section and located axially aft of the outer body section, and wherein the bolting arrangement further includes a second captured nut fixed to the aft attachment flange and a second attachment fastener that extends radially through the outer radial surface of the annular case, the inner radial surface of the annular case, and into the second cavity to mate with the second captured nut.
10. The fan case assembly of claim 1 , further comprising a seal positioned axially between an aft end of the inner body section and the annular case.
11. A fan case assembly adapted to extend around blades of a fan rotor included in a gas turbine engine, the fan case assembly comprising
an annular case that extends around an axis,
an acoustic panel coupled to the annular case and configured to dampen vibrations, the acoustic panel extending circumferentially at least partway about the axis and including a panel body and an attachment flange, the panel body including an outer body section and an inner body section, the attachment flange extends axially away from the outer body section of the panel body and is spaced apart radially from the inner body section to define a cavity radially between the attachment flange and the inner body section of the panel body, and
a bolting arrangement that couples the acoustic panel to the annular case, the bolting arrangement including a first captured nut and a first attachment fastener, the first captured nut positioned between the attachment flange and the inner body section in the cavity, and the first attachment fastener extends radially through the annular case, through the attachment flange, and mates with the first captured nut in the cavity to couple the acoustic panel with the annular case.
12. The fan case assembly of claim 11 , wherein the attachment flange has a first radial thickness and the inner body section has a second radial thickness greater than the first radial thickness.
13. The fan case assembly of claim 12 , wherein the outer body section has a third radial thickness greater than the first radial thickness and equal to or less than the second radial thickness.
14. The fan case assembly of claim 11 , wherein first attachment fastener has a radially outer end positioned radially outward of the annular case and a radially inner end positioned in the cavity.
15. The fan case assembly of claim 14 , wherein the inner body section is formed without any attachment through holes such that no fasteners extend through the inner body section.
16. The fan case assembly of claim 15 , wherein the outer body section is formed without any attachment through holes such that no fasteners extend into the outer body section.
17. The fan case assembly of claim 11 , wherein the cavity is formed in a forward end of the acoustic panel and opens in an axially-forward direction.
18. The fan case assembly of claim 11 , wherein the first captured nut is a riveted nutplate that is fixed to a radially inner surface of the attachment flange.
19. The fan case assembly of claim 11 , wherein the attachment flange is a forward attachment flange coupled to a forward end of the outer body section and the acoustic panel further includes an aft attachment flange coupled to an aft end of the outer body section and arranged to lie radially between the annular case and the inner body section, the aft attachment flange cooperating with the inner body section to define a second cavity radially between the aft attachment flange and the inner body section and located axially aft of outer body section, and wherein the bolting arrangement further includes a second captured nut fixed to the aft attachment flange and a second attachment fastener that extends radially through the outer radial surface of the annular case, the inner radial surface of the annular case, and into the second cavity to mate with the second captured nut.
20. The fan case assembly of claim 1 , further comprising a seal positioned axially between an aft end of the inner body section and the annular case.