The invention relates to a profiled structure elongated in a direction in which the structure has a length exposed to an airflow and transversely to which the structure has a leading edge and/or a trailing edge, at least one of which is profiled and has, along said direction of elongation, geometric serration patterns defined by a succession of peaks and troughs. Along the profiled leading edge and/or trailing edge, the serration patterns have a geometric pattern that is repeated in the direction of elongation, the shape of which is stretched and/or contracted transversely to the direction of elongation and/or in the direction of elongation.

Systems and methods are provided for experimentally determining optimized placement and operating conditions, e.g., amplitude, phase, or frequency, of active flow control actuators by executing an optimization routine to sequentially activate varying subsets of active flow control actuators of a plurality of active flow control actuators spatially distributed within a flow field, calculating a cost function of each of the subsets of sequentially activated active flow control actuators based on respective measurements of one or more parameters, e.g., integral variables or proxies to the integral variables, within the flow field by one or more sensors, and determining an optimal subset of active flow control actuators based on the respective cost functions of each of the subsets of sequentially activated active flow control actuators.

Systems and methods are described herein to implement transverse momentum injection at low frequencies to directly modify large-scale eddies in a turbulent boundary layer on a surface of an object. A set of transverse momentum injection actuators may be positioned on the surface of the object to affect large-scale eddies in the turbulent boundary layer. The system may include a controller to selectively actuate the transverse momentum injection actuators with an actuation pattern to affect the large-scale eddies to modify the drag of the fluid flow on the surface. In various embodiments, the transverse momentum injection actuators may be operated at frequencies less than 10,000 Hertz.

A system includes a surface having a fluid flowing over the surface. The fluid includes a flow regime having a streamwise length scale greater than about 100 times η and less than about 100,000 times η, where η is a viscous length scale of the flow regime, and a convective time scale greater than about 10η′ and less than about 10,000η′, where η′ is a viscous time scale of the flow regime. The system includes a controller that causes at least one of motion the surface to modify fluid flow in the flow regime based on the streamwise length scale and the convective time scale or motion of the flow regime based on the streamwise length scale and the convective time scale.

A vehicle, includes a main body. A fluid generator is coupled to the main body and produces a fluid stream. At least one fore conduit and at least one tail conduit are fluidly coupled to the generator. First and second fore ejectors are fluidly coupled to the fore conduit, coupled to the main body and respectively coupled to a starboard side and port side of the vehicle. The fore ejectors respectively comprise an outlet structure out of which fluid flows. At least one tail ejector is fluidly coupled to the tail conduit. The tail ejector comprises an outlet structure out of which fluid flows. A primary airfoil element is coupled to the tail portion. A surface of the primary airfoil element is located directly downstream of the first and second fore ejectors such that the fluid from the first and second fore ejectors flows over the such surface.

A vehicle, includes a main body. A fluid generator is coupled to the main body and produces a fluid stream. At least one fore conduit and at least one tail conduit are fluidly coupled to the generator. First and second fore ejectors are fluidly coupled to the fore conduit, coupled to the main body and respectively coupled to a starboard side and port side of the vehicle. The fore ejectors respectively comprise an outlet structure out of which fluid flows. At least one tail ejector is fluidly coupled to the tail conduit. The tail ejector comprises an outlet structure out of which fluid flows. A primary airfoil element is coupled to the tail portion. A surface of the primary airfoil element is located directly downstream of the first and second fore ejectors such that the fluid from the first and second fore ejectors flows over the such surface.

An aircraft having reverse thrust capabilities includes a fuselage, a plurality of flight components, a pilot control located within the fuselage, a sensor attached to the pilot control configured to detect an aircraft datum from the pilot control, and a flight controller, located within the fuselage, the flight controller configured to receive the aircraft datum from the sensor, and initiate a reverse torque command of a flight component of the plurality of flight components as a function of the aircraft datum.

An aircraft having reverse thrust capabilities includes a fuselage, a plurality of flight components, a pilot control located within the fuselage, a sensor attached to the pilot control configured to detect an aircraft datum from the pilot control, and a flight controller, located within the fuselage, the flight controller configured to receive the aircraft datum from the sensor, and initiate a reverse torque command of a flight component of the plurality of flight components as a function of the aircraft datum.

A boundary layer ingestion-open rotor system for use with an aircraft having a fuselage, wings, and an empennage includes an open rotor assembly, one or more energy storage systems, and an electronic control unit (ECU). The open rotor assembly includes fan blades connected to and extending radially from a rotor hub, and a linkage assembly connecting the hub to the fuselage aft of the empennage within a predefined boundary layer of airflow around the fuselage. The energy storage systems are connectable to the rotor hub. In response to an electronic control signal, the system(s) selectively energize the open rotor assembly to cause rotation of the hub to occur within the boundary layer. The ECU selectively generates the electronic control signals to energize the open rotor assembly during one or more predetermined flight operating phases of the aircraft, e.g., cruise, takeoff, landing, and descent.

A boundary layer ingestion-open rotor system for use with an aircraft having a fuselage, wings, and an empennage includes an open rotor assembly, one or more energy storage systems, and an electronic control unit (ECU). The open rotor assembly includes fan blades connected to and extending radially from a rotor hub, and a linkage assembly connecting the hub to the fuselage aft of the empennage within a predefined boundary layer of airflow around the fuselage. The energy storage systems are connectable to the rotor hub. In response to an electronic control signal, the system(s) selectively energize the open rotor assembly to cause rotation of the hub to occur within the boundary layer. The ECU selectively generates the electronic control signals to energize the open rotor assembly during one or more predetermined flight operating phases of the aircraft, e.g., cruise, takeoff, landing, and descent.