Passive, low drag device for pylon-nacelle juncture flow separation mitigation

An aircraft comprising:

• a fuselage;
• a pylon having a leading edge, a trailing edge, a first end extending between the leading and trailing edges, a second end opposite the first end, a first surface extending between the first end and the second end and between the leading and trailing edges, and a second surface facing opposite the first surface, wherein the first end is fixed to the fuselage;
• a first protrusion that extends outward from the first surface of the pylon;
• an aircraft engine fixed to the second end of the pylon;
• and
• a nacelle formed around the aircraft engine, the nacelle having a leading end, a trailing end, and a tapered boattail at the trailing end, wherein the first protrusion is located between the fuselage and the tapered boattail, wherein the first protrusion has a protrusion leading end, a protrusion trailing end, and a middle section somewhere between the protrusion leading end and the protrusion trailing end, wherein a cross-sectional area of the first protrusion gradually expands in size from the protrusion leading end to the middle section.

An aircraft body comprising:

• a plurality of aircraft external surfaces cooperatively forming a channel extending in a forward to aftward direction, wherein an aft portion of the channel gradually increases in cross-sectional area in the forward to aftward direction;
• a juncture at which two adjacent ones of the plurality of aircraft external surfaces meet;
• and
• a protrusion extending outward from one of the two adjacent ones of the plurality of aircraft external surfaces into the aft portion of the channel, wherein the protrusion is spaced apart from the juncture, wherein the protrusion is sized and shaped to mitigate boundary layer separation within the aft portion of the channel when a flow of air moves through the channel in the forward to aftward direction.