Abstract: A turbofan engine and an outlet guide vane structure for the turbofan engine is provided. The outlet guide vane structure includes a non-uniform plurality of outlet guide vanes utilized in a bypass duct and between a radially inward wall and a radially outward wall. The non-uniform plurality of outlet guide vanes have varying chord lengths at the base of the outlet guide vanes along the radially inward wall. The non-uniform plurality of outlet guide vanes may include structural outlet guide vanes, non-structural outlet guide vanes, and cut-out outlet guide vanes. The non-uniform plurality of outlet guide vanes include at least one outlet guide vane integrated with a pylon and/or a bifurcation of the turbofan engine. The cut-out outlet guide vane may be integrated with the pylon and/or bifurcation. The cut-out may include a leading edge and a trailing edge disposed in front of a leading edge of the pylon.

Abstract: A turbofan engine and an outlet guide vane structure for the turbofan engine is provided. The outlet guide vane structure includes a non-uniform plurality of outlet guide vanes utilized in a bypass duct and between a radially inward wall and a radially outward wall. The non-uniform plurality of outlet guide vanes have varying chord lengths at the base of the outlet guide vanes along the radially inward wall. The non-uniform plurality of outlet guide vanes may include structural outlet guide vanes, non-structural outlet guide vanes, and cut-out outlet guide vanes. The non-uniform plurality of outlet guide vanes include at least one outlet guide vane integrated with a pylon and/or a bifurcation of the turbofan engine. The cut-out outlet guide vane may be integrated with the pylon and/or bifurcation. The cut-out may include a leading edge and a trailing edge disposed in front of a leading edge of the pylon.

Abstract: An aircraft comprising a fuselage and an unducted turbine engine. The fuselage having a divot with an upstream edge and a downstream edge. The divot is defined by a straight reference line having a length (L) and a maximum depth (h) relative to the straight reference line. The unducted turbine engine having an engine core, a nacelle, and a set of blades. A first flow ratio (FR1) is equal to: h/L.

Abstract: An aircraft comprising a fuselage and an unducted turbine engine. The fuselage having a divot with an upstream edge and a downstream edge. The divot is defined by a straight reference line having a length (L) and a maximum depth (h) relative to the straight reference line. The unducted turbine engine having an engine core, a nacelle, and a set of blades. A first flow ratio (FR1) is equal to: h L .

Abstract: A gas turbine engine comprises a fan, a core turbine engine coupled to the fan, a fan case housing the fan and the core turbine engine, a plurality of outlet guide vanes extending between the core turbine engine and the fan case, and an acoustic spacing. The fan comprises a plurality of fan blades that define a fan diameter and a BEAL. The fan case comprises an inlet and an inlet length between the inlet and the fan. The acoustic spacing comprises a distance between the fan and the plurality of outlet guide vanes, and in combination with the BEAL determines an acoustic spacing ratio of the gas turbine engine.

Abstract: A gas turbine engine comprises a fan, a core turbine engine coupled to the fan, a fan case housing the fan and the core turbine engine, a plurality of outlet guide vanes extending between the core turbine engine and the fan case, and an acoustic spacing. The fan comprises a plurality of fan blades that define a fan diameter and a BEAL. The fan case comprises an inlet and an inlet length between the inlet and the fan. The acoustic spacing comprises a distance between the fan and the plurality of outlet guide vanes, and in combination with the BEAL determines an acoustic spacing ratio of the gas turbine engine.

Abstract: Acoustic turbofan airfoil apparatus are disclosed. An example apparatus includes a platform of a turbofan engine, the platform including perforations to receive acoustic waves, acoustic chambers protruding from a first side of the platform, the acoustic chambers aligned with the perforations in a radial direction defined by the turbofan engine, the acoustic chambers to attenuate the acoustic waves, and an airfoil protruding from a second side of the platform opposite the first side of the platform.

Abstract: An aircraft comprising a fuselage and an unducted turbine engine. The fuselage having a divot with an upstream edge and a downstream edge. The divot is defined by a straight reference line having a length (L) and a maximum depth (h) relative to the straight reference line. The unducted turbine engine having an engine core, a nacelle, and a set of blades. A first flow ratio (FR1) is equal to: h/L.

Abstract: Turbofan blade blocking apparatus are disclosed. An example turbofan engine includes a containment casing, a fan, at least one of a trench filler or an abradable layer at least partially aligned with the fan in an axial direction defined by the turbofan engine, at least one of the trench filler or the abradable layer fixed to an inner radial surface of the containment casing, and a metal blocker coupled to the containment casing forward of the fan, an aft end of the metal blocker interfacing with at least one of the trench filler or the abradable layer.

Abstract: Turbofan blade blocking apparatus are disclosed. An example turbofan engine includes a containment casing, a fan, at least one of a trench filler or an abradable layer at least partially aligned with the fan in an axial direction defined by the turbofan engine, at least one of the trench filler or the abradable layer fixed to an inner radial surface of the containment casing, and a metal blocker coupled to the containment casing forward of the fan, an aft end of the metal blocker interfacing with at least one of the trench filler or the abradable layer.

Abstract: Acoustic turbofan airfoil apparatus are disclosed. An example apparatus includes a platform of a turbofan engine, the platform including perforations to receive acoustic waves, acoustic chambers protruding from a first side of the platform, the acoustic chambers aligned with the perforations in a radial direction defined by the turbofan engine, the acoustic chambers to attenuate the acoustic waves, and an airfoil protruding from a second side of the platform opposite the first side of the platform.

Abstract: An acoustic liner may include an acoustic core having an array of resonant cells, and an acoustic screen disposed across the array of resonant cells. The resonant cells include a plurality of cell walls and a resonant space defined by the plurality of cell walls. The acoustic core may include a folded acoustic core. Additionally, or in the alternative, at least some of the resonant cells may include an oblique polyhedral cellular structure and/or a multitude of sound-attenuating protuberances. The acoustic screen may include a reticulate membrane and a support lattice.

Abstract: An acoustic panel comprises: a face sheet comprising a plurality of openings; a back sheet opposite to the face sheet; and an intermediate layer comprising a plurality of cells each comprising a cavity and a plurality of walls extending between the face sheet and the back sheet and surrounding the cavity, the plurality of walls comprising a plurality of drainage slots and a plurality of covers covering the plurality of drainage slots and openable for drainage. A method for making the acoustic panel is also described.

Abstract: An acoustic liner may include an acoustic core having an array of resonant cells, and an acoustic screen disposed across the array of resonant cells. The resonant cells include a plurality of cell walls and a resonant space defined by the plurality of cell walls. The acoustic core may include a folded acoustic core. Additionally, or in the alternative, at least some of the resonant cells may include an oblique polyhedral cellular structure and/or a multitude of sound-attenuating protuberances. The acoustic screen may include a reticulate membrane and a support lattice.

Abstract: An acoustic panel comprises: a face sheet comprising a plurality of openings; a back sheet opposite to the face sheet; and an intermediate layer comprising a plurality of cells each comprising a cavity and a plurality of walls extending between the face sheet and the back sheet and surrounding the cavity, the plurality of walls comprising a plurality of drainage slots and a plurality of covers covering the plurality of drainage slots and openable for drainage. A method for making the acoustic panel is also described.

Abstract: An acoustic panel comprises a face sheet comprising a plurality of openings; a back sheet opposite to the face sheet; and an intermediate layer comprising a plurality of cells each comprising a cavity and a plurality of walls extending between the face sheet and the back sheet and surrounding the cavity. The plurality of walls can comprise at least one and possibly a plurality of slots for drainage. A method for making the acoustic panel is also described.

Abstract: A single degree of freedom (SDOF) acoustic liner includes a porous face sheet, a substantially imperforate back sheet generally parallel to and opposing said porous face sheet and defining a thickness therebetween, and an acoustic core layer of contiguous adjacent resonant cavities disposed between the porous face sheet and the imperforate back sheet. The acoustic core layer includes a first resonant cell having a first internal volume therein and a second resonant cell having a second internal volume therein different than the first internal volume. A cell partition wall extends between the porous face sheet and the imperforate back sheet, and separates and seals the first resonant cell from the second resonant cell. In a thickness direction, and perpendicular to a plane generally parallel with the porous face sheet and the substantially imperforate back sheet, the first internal volume overlaps the second internal volume over the cell partition wall.

Abstract: A single degree of freedom (SDOF) acoustic liner includes a porous face sheet, a substantially imperforate back sheet generally parallel to and opposing said porous face sheet and defining a thickness therebetween, and an acoustic core layer of contiguous adjacent resonant cavities disposed between the porous face sheet and the imperforate back sheet. The acoustic core layer includes a first resonant cell having a first internal volume therein and a second resonant cell having a second internal volume therein different than the first internal volume. A cell partition wall extends between the porous face sheet and the imperforate back sheet, and separates and seals the first resonant cell from the second resonant cell. In a thickness direction, and perpendicular to a plane generally parallel with the porous face sheet and the substantially imperforate back sheet, the first internal volume overlaps the second internal volume over the cell partition wall.