A propulsion system coupled to a vehicle. The system includes a diffusing structure and a conduit portion configured to introduce to the diffusing structure through a passage a primary fluid produced by the vehicle. The passage is defined by a wall, and the diffusing structure comprises a terminal end configured to provide egress from the system for the introduced primary fluid. A constricting element is disposed adjacent the wall. An actuating apparatus is coupled to the constricting element and is configured to urge the constricting element toward the wall, thereby reducing the cross-sectional area of the passage.

A propulsion system coupled to a vehicle. The system includes a diffusing structure and a conduit portion configured to introduce to the diffusing structure through a passage a primary fluid produced by the vehicle. The passage is defined by a wall, and the diffusing structure comprises a terminal end configured to provide egress from the system for the introduced primary fluid. A constricting element is disposed adjacent the wall. An actuating apparatus is coupled to the constricting element and is configured to urge the constricting element toward the wall, thereby reducing the cross-sectional area of the passage.

A turbofan engine comprises a nacelle and an engine core having a core cowling. The internal surface of the nacelle and the external surface of the core cowling define a bypass duct having an exhaust end defining a bypass duct exit plane generally normal to the longitudinal axis of the engine. The core cowling extends aft of the bypass duct exit plane and has an annular or partly-annular exit ventilation nozzle located aft of a first longitudinal position and fore of a second longitudinal position, the first and second longitudinal positions being respectively fore of and either aft of or coincident with the bypass duct exit plane, the core cowling otherwise being free of exit ventilation nozzles fore of the second longitudinal position. The engine has a lower specific fuel consumption than an equivalent engine having an exit ventilation nozzle in a conventional position aft of the second longitudinal position.

Methods are provided for creating a fluidic barrier between the core stream and the bypass stream in a turbofan engine. A method comprises compressing the bypass and core streams with a fan between an upstream splitter and a downstream splitter which divides the bypass and core streams, and imparting a first momentum into the air stream proximate the fan in a region between the core and bypass streams and the upstream and downstream splitters to form a fluid barrier, wherein the first momentum of the air stream in the region is higher than a second momentum of the air stream adjacent the fluid barrier.

Methods are provided for creating a fluidic barrier between the core stream and the bypass stream in a turbofan engine. A method comprises compressing the bypass and core streams with a fan between an upstream splitter and a downstream splitter which divides the bypass and core streams, and imparting a first momentum into the air stream proximate the fan in a region between the core and bypass streams and the upstream and downstream splitters to form a fluid barrier, wherein the first momentum of the air stream in the region is higher than a second momentum of the air stream adjacent the fluid barrier.

The present disclosure provides systems and apparatuses for use in turbine systems that integrate structural frame elements into a variable-vectoring flow control configuration in order to reduce the weight and length of such turbine systems. In one exemplary embodiment, an apparatus for directing a gas flow includes an annular outer structural casing, an annular central hub disposed within the outer structural casing, and a plurality of structural support elements extending radially between the central hub and the outer structural casing. The apparatus further includes a plurality of positionally-fixed, variable-vectoring flow control bodies extending radially between the central hub and the outer structural casing and positioned circumferentially along the central hub between ones of the plurality of structural support elements.

The present disclosure provides systems and apparatuses for use in turbine systems that integrate structural frame elements into a variable-vectoring flow control configuration in order to reduce the weight and length of such turbine systems. In one exemplary embodiment, an apparatus for directing a gas flow includes an annular outer structural casing, an annular central hub disposed within the outer structural casing, and a plurality of structural support elements extending radially between the central hub and the outer structural casing. The apparatus further includes a plurality of positionally-fixed, variable-vectoring flow control bodies extending radially between the central hub and the outer structural casing and positioned circumferentially along the central hub between ones of the plurality of structural support elements.

The present disclosure provides a nozzle for an aircraft turboprop engine with an unducted fan, including: an inner wall, an outer wall radially spaced apart from the inner wall and concentric with the inner wall, a junction area of the inner and outer walls including an opening contained in a plane transverse to a longitudinal axis of the nozzle. In particular, the junction area of the inner and outer walls includes two connecting plates and a member to secure the two connecting plates together, or in another form, the junction area includes a pad secured to the inner wall, and a pad secured to the outer wall, facing the pad of the inner wall of the nozzle.

The present disclosure provides a nozzle for an aircraft turboprop engine with an unducted fan, including: an inner wall, an outer wall radially spaced apart from the inner wall and concentric with the inner wall, a junction area of the inner and outer walls including an opening contained in a plane transverse to a longitudinal axis of the nozzle. In particular, the junction area of the inner and outer walls includes two connecting plates and a member to secure the two connecting plates together, or in another form, the junction area includes a pad secured to the inner wall, and a pad secured to the outer wall, facing the pad of the inner wall of the nozzle.

A nozzle effective exit area control system is created with a convergent-divergent nozzle with a divergent portion of the nozzle having a wall at a predetermined angle of at least 12 from the freestream direction. Disturbance generators are located substantially symmetrically oppositely on the wall to induce flow separation from the wall with the predetermined wall angle inducing flow separation to extend upstream from each disturbance generator substantially to a throat of the nozzle pressurizing the wall and reducing the effective area of the jet flow at the nozzle exit.