Abstract: An ultrashort nacelle configuration employs a fan cowl having an exit plane and a serrated trailing edge. A variable pitch fan is housed within the fan cowl. The variable pitch fan has a reverse thrust position inducing a reverse flow through the exit plane and into the fan cowl. The serrated trailing edge forms a plurality of vortex generators configured to induce vortices in the reverse flow.

Abstract: There is provided a turbofan engine for an aircraft. The turbofan engine has a core with a fan cowl and a variable pitch fan (VPF) configured to only rotate in a first rotation direction. The VPF has a plurality of fan blades each configured to over-pitch to an over-pitch position relative to a feathered position. The turbofan engine has outer guide vanes (OGVs) axially disposed downstream of the VPF, and has a rotation control device to prevent the VPF from rotating in a second rotation direction opposite the first rotation direction, during an engine out (EO) condition of the turbofan engine. When the VPF is prevented from rotating during the EO condition, the fan blades are over-pitched to the over-pitch position relative to the feathered position, to achieve no or minimal air flow separation about the OGVs, and to reduce drag of the turbofan engine during the EO condition.

Abstract: There is provided a propulsion system for an aircraft, the system having a low-fan-pressure-ratio engine configured to be mounted, in a forward over-wing-flow installation, to a wing of the aircraft. The engine has a core, a variable pitch fan, and a nacelle having a nacelle trailing edge with a top-most portion positioned above a wing leading edge. The engine has an L/D ratio of the nacelle in a range of from 0.6 to 1.0, and a fan-pressure-ratio in a range of from 1.10 to 1.30. The forward over-wing-flow installation enables, during all flight phases of the aircraft, a fan flow exhaust to flow behind the nacelle, and to be bifurcated by the wing leading edge, so the fan flow exhaust flows both over the wing and under the wing. During a cruise flight phase of the aircraft, the engine minimizes scrubbing drag of the fan flow exhaust to the wing.

Abstract: There is provided a turbofan engine for an aircraft. The turbofan engine has a core with a fan cowl and a variable pitch fan (VPF) configured to only rotate in a first rotation direction. The VPF has a plurality of fan blades each configured to over-pitch to an over-pitch position relative to a feathered position. The turbofan engine has outer guide vanes (OGVs) axially disposed downstream of the VPF, and has a rotation control device to prevent the VPF from rotating in a second rotation direction opposite the first rotation direction, during an engine out (EO) condition of the turbofan engine. When the VPF is prevented from rotating during the EO condition, the fan blades are over-pitched to the over-pitch position relative to the feathered position, to achieve no or minimal air flow separation about the OGVs, and to reduce drag of the turbofan engine during the EO condition.

Abstract: There is provided a propulsion system for an aircraft, the system having a low-fan-pressure-ratio engine configured to be mounted, in a forward over-wing-flow installation, to a wing of the aircraft. The engine has a core, a variable pitch fan, and a nacelle having a nacelle trailing edge with a top-most portion positioned above a wing leading edge. The engine has an L/D ratio of the nacelle in a range of from 0.6 to 1.0, and a fan-pressure-ratio in a range of from 1.10 to 1.30. The forward over-wing-flow installation enables, during all flight phases of the aircraft, a fan flow exhaust to flow behind the nacelle, and to be bifurcated by the wing leading edge, so the fan flow exhaust flows both over the wing and under the wing. During a cruise flight phase of the aircraft, the engine minimizes scrubbing drag of the fan flow exhaust to the wing.

Abstract: An ultrashort nacelle configuration employs a fan cowl having an exit plane and a serrated trailing edge. A variable pitch fan is housed within the fan cowl. The variable pitch fan has a reverse thrust position inducing a reverse flow through the exit plane and into the fan cowl. The serrated trailing edge forms a plurality of vortex generators configured to induce vortices in the reverse flow.

Abstract: A vortex generator may include a depression in an aerodynamic surface, and a vortex generator leading edge located in the depression. The vortex generator leading edge may include a leading edge upper surface. The leading edge upper surface may be positioned at or below a tangent line defined at a location along the aerodynamic surface upstream of the depression relative to an oncoming local flow.

Abstract: A vortex generator may include a depression in an aerodynamic surface, and a vortex generator leading edge located in the depression. The vortex generator leading edge may include a leading edge upper surface. The leading edge upper surface may be positioned at or below a tangent line defined at a location along the aerodynamic surface upstream of the depression relative to an oncoming local flow.