Dual flow APU inlet and associated systems and methods

An inlet system for an aircraft auxiliary power unit, comprising:

• an aircraft fuselage portion;
• an inlet having an entrance aperture, the entrance aperture having a first surface portion positioned proximate to a surface of the aircraft fuselage portion, a second surface portion spaced apart from the first surface portion and located aft of the first surface portion, and third and fourth surface portions extending between the first and second surface portions;
• and
• a divider positioned in the inlet and generally aligned with the third surface portion, wherein the inlet includes a first flow channel between the divider and the fourth surface portion, and a second flow channel between the divider and the third surface portion, the first flow channel being configured to couple to an engine air intake of an aircraft auxiliary power unit, the second flow channel being configured to direct air away from the air intake, the first flow channel being positioned to direct air having a first total pressure level and a first distortion level, the second flow channel being positioned to direct air having a second total pressure level and a second distortion level, with
• (a) the first total pressure level higher than the second total pressure level, and
• (b) the second distortion level higher than the first distortion level.

An inlet system for an aircraft auxiliary power unit, comprising:

• an aircraft fuselage portion;
• an inlet having an entrance aperture, the entrance aperture having a first surface portion positioned proximate to a surface of the aircraft fuselage portion, a second surface portion spaced apart from the first surface portion and located aft of the first surface portion, and third and fourth surface portions extending between the first and second surface portions;
• and
• a divider positioned in the inlet and generally aligned with the first surface portion, wherein the inlet includes a first flow channel between the divider and the second surface portion, and a second flow channel between the divider and the first surface portion, the first flow channel being configured to be coupled to an engine air intake of an aircraft auxiliary power unit, the second flow channel being configured to direct air away from the air intake, the first flow channel being positioned to direct air having a first total pressure level and a first distortion level, the second flow channel being positioned to direct air having a second total pressure level and a second distortion level, with:
• (a) the first total pressure level higher than the second total pressure level;
• or
• (b) the second distortion level higher than the first distortion level;
• or
• (c) both (a) and (b).

An inlet system for an aircraft auxiliary power unit, comprising:

• an inlet having an entrance aperture;
• and
• separation means for separating flow in the inlet into a first portion directed to an engine air intake of an aircraft auxiliary power unit and a second portion directed away from the air intake, the first portion having a first total pressure level and a first distortion level and the second portion having a second total pressure level and a second distortion level, with
• (a) the first total pressure level higher than the second total pressure level, and
• (b) the second distortion level higher than the first distortion level.

An aircraft, comprising:

• a fuselage;
• a wing;
• an auxiliary power unit compartment carried by at least one of the fuselage and the wing;
• an auxiliary power unit having an air intake and being housed in the auxiliary power unit compartment;
• an inlet having an entrance aperture;
• and
• a divider positioned in the inlet, the divider being located to separate a first portion of the inlet from a second portion of the inlet, the first portion being coupled to the air intake of aircraft auxiliary power unit, the second portion being positioned to direct air away from the air intake and into the auxiliary power unit compartment, the divider being positioned to direct air having a first total pressure level and a first distortion level to the first portion of the inlet, and direct air having a second total pressure level and a second distortion level to the second portion of the inlet, with
• (a) the first total pressure level higher than the second total pressure level, and
• (b) the second distortion level higher than the first distortion level.

An aircraft, comprising:

• a fuselage;
• a wing;
• an auxiliary power unit compartment carried by at least one of the fuselage and the wing;
• an auxiliary power unit having an air intake and being housed in the auxiliary power unit compartment;
• an inlet having an entrance aperture, the entrance aperture having a first surface portion positioned to be proximate to a surface of the fuselage, a second surface portion spaced apart from and aft of the first surface portion, and third and fourth surface portions extending between the first and second surface portions;
• a first divider positioned in the inlet and generally aligned with the third surface portion;
• a second divider positioned in the inlet and generally aligned with the fourth surface portion, wherein the inlet includes a first flow channel between the first and second dividers, a second flow channel between the first divider and the third surface portion, and a third flow channel between the second divider and the fourth surface portion, the first flow channel being coupled to the engine, air intake of the aircraft auxiliary power unit, the second and third flow channels being directed into the auxiliary power unit compartment;
• and
• an inlet door positioned at least proximate to the entrance aperture of the inlet, the inlet door being movable relative to the inlet aperture between an open position and a closed position, and wherein at least part of the inlet door sealably engages the first and second dividers when the inlet door is in the closed position.

A method for providing flow to an aircraft auxiliary power unit, comprising:

• receiving flow in an inlet;
• providing a first portion of the flow having a first total pressure level and a first distortion level to an engine air intake of an auxiliary power unit;
• and
• directing a second portion of the flow having a second total pressure level and a second distortion level away from the engine air intake, wherein
• (a) the first total pressure level is higher than the second total pressure level, and
• (b) the second distortion level is higher than the first distortion level.

A method for providing flow to an aircraft auxiliary power unit, comprising:

• receiving a flow of air in an inlet having a first surface portion positioned to be proximate to an aircraft fuselage, a second surface portion spaced apart from the first surface portion, and third and fourth surface portions extending between the first and second surface portions;
• a first divider positioned in the inlet and generally aligned with the third surface portion;
• a second divider positioned in the inlet duct and generally aligned with the fourth surface portion;
• separating flow in a first flow channel between the first and second dividers from flow in a second flow channel between the first divider and the third surface portion, and from flow in a third flow channel between the second divider and the fourth surface portion;
• directing the flow in the first flow channel to an engine air intake of an aircraft auxiliary power unit;
• and
• directing the flows in the second and third flow channels to a compartment in which the auxiliary power unit is housed.

An inlet system for an aircraft auxiliary power unit, comprising:

• an inlet having an entrance aperture;
• and
• first and second dividers positioned in the inlet, the dividers being located to separate a first portion of the inlet from second and third portions of the inlet, the first portion being configured to couple to an engine air intake of an aircraft auxiliary power unit, the second and third portions being configured to direct air away from the air intake, the dividers being positioned to direct air having a first total pressure level and a first distortion level to the first portion of the inlet, and direct air having a second total pressure level and a second distortion level to the second portion of the inlet, with
• (a) the first total pressure level higher than the second total pressure level, or
• (b) the second distortion level higher than the first distortion level, or both (a) and (b).

An inlet system for an aircraft auxiliary power unit, comprising:

• an inlet having an entrance aperture;
• and
• separation means for separating flow in the inlet into a first portion directed to an engine air intake of an aircraft auxiliary power unit and a second portion directed away from the air intake, wherein the separation means includes a first divider and a second divider and wherein the first portion of the flow passes between the two dividers, the first portion having a first total pressure level and a first distortion level and the second portion having a second total pressure level and a second distortion level, with
• (a) the first total pressure level higher than the second total pressure level, or
• (b) the second distortion level higher than the first distortion level, or both (a) and (b).

An aircraft, comprising:

• a fuselage;
• a wing;
• an auxiliary power unit compartment carried by at least one of the fuselage and the wing;
• an auxiliary power unit having an air intake and being housed in the auxiliary power unit compartment;
• an inlet having an entrance aperture;
• and
• first and second dividers positioned in the inlet to separate a first portion of the inlet from a second portion of the inlet, the first portion being positioned between the first and second dividers and being coupled to the air intake of aircraft auxiliary power unit, the second portion being positioned to direct air away from the air intake and into the auxiliary power unit compartment, the divider being positioned to direct air having a first total pressure level and a first distortion level to the first portion of the inlet, and direct air having a second total pressure level and a second distortion level to the second portion of the inlet, with
• (a) the first total pressure level higher than the second total pressure level, or
• (b) the second distortion level higher than the first distortion level, or both (a) and (b).