Example active flow control systems and methods for aircraft are described herein. An example active flow control system includes a plurality of nozzles arranged in an array across a surface of an aircraft. The nozzles are oriented to eject air across the surface to reduce airflow separation. The active flow control system also includes an air source coupled to the nozzles and a controller to activate the nozzles to eject air from the air source in sequence from outboard to inboard and then from inboard to outboard to create a wave of air moving from outboard to inboard and then from inboard to outboard across the surface.

An active flow control drag-induced damping reduction apparatus. The apparatus includes a variable frequency signal power supply; a jet generator defining an internal cavity and having pump member, and coupled to the variable frequency signal power supply to receive a control signal; a feedback sensor coupled to the pump member to generate a feedback signal measuring the reciprocating motion of the pump member; a detection circuit that receives the feedback signal and measures a difference compared to the variable frequency generator; and an adjustment circuit that receives the measured difference and tunes the variable frequency signal of the variable frequency signal power supply to maintain the jet generator at an optimum flow.

Methods and systems for controlling a fluid flow field near a surface are disclosed. In some embodiments, the system includes an array of oscillating bodies disposed on the surface to provide physical modification to the flow field. Fluid jets are also emitted from an outlet in the oscillating body to provide virtual modification of the flow field through momentum addition. Fluid jet sources, including synthetic jet generators such as piezoelectric drivers and sources of compressed fluids such as air or water, are positioned to be in fluid communication with the outlet at intervals during the oscillation of the oscillating body. Controlling the oscillation amplitude and frequency of the body, as well as the location of oscillating body outlets and frequency of fluid jet emission, have advantageous effects for the surface such as improved heat transfer properties and reduction in structural vibration and noise.

A removable passive airflow oscillation device can be disposed within a pressurized wing structure utilized as a plenum. The passive airflow oscillation device can be a removable insert disposed into exterior vehicle surfaces with pressurization of a sealed chamber to provide the airflow. The device can include a cavity configured to receive the airflow from an ingress opening, direct the airflow therethrough to generate a predetermined oscillating airflow, and expel the oscillatory airflow from the egress opening. The removable passive airflow oscillation devices can provide quick and simple replacement and maintenance of damaged or clogged devices. The aft chamber of the flap seal can be sealed and pressurized to serve as a plenum providing the airflow to the actuators. The device can receive airflow, such as compressor air, and expel an oscillating airflow. Because each device is self-contained the number of devices and location thereof can vary by application.

A method, apparatus, and system for managing airflow comprising flow control actuators in an aircraft. The flow control actuators comprise channels having inlets and outlets, wherein the channels are located under a surface of the aircraft and the outlets are in communication with the surface of the aircraft. Pressurized air applied to the inlets causes steady air jets to be emitted at the outlets in which the steady air jets add a momentum to airflow over the surface on the aircraft.

Example active flow control systems and methods for aircraft are described herein. An example active flow control system includes a plurality of nozzles arranged in an array across a surface of an aircraft. The nozzles are oriented to eject air across the surface to reduce airflow separation. The active flow control system also includes an air source coupled to the nozzles and a controller to activate the nozzles to eject air from the air source in sequence from outboard to inboard and then from inboard to outboard to create a wave of air moving from outboard to inboard and then from inboard to outboard across the surface.

Method and apparatus for controlling the aerodynamics of an aircraft using an active flow control system is disclosed herein. In one example, the active flow control system includes an airframe and a plurality of fluidic oscillators. The airframe includes an inlet configured for flight speeds ranging from subsonic to hypersonic. The plurality of fluidic oscillators is mounted about a curvature of the airframe. Each fluidic oscillator includes a body and an integral nozzle coupled to the body. The body has an inflow portion and a narrow nozzle inlet formed opposite the inflow portion. The integral nozzle is coupled to the body by the narrow nozzle inlet. The narrow nozzle inlet forms a single fluid flow path from the inflow portion to the narrow nozzle inlet.

Methods and systems for controlling a fluid flow field near a surface are disclosed. In some embodiments, the system includes an array of oscillating bodies disposed on the surface to provide physical modification to the flow field. Fluid jets are also emitted from an outlet in the oscillating body to provide virtual modification of the flow field through momentum addition. Fluid jet sources, including synthetic jet generators such as piezoelectric drivers and sources of compressed fluids such as air or water, are positioned to be in fluid communication with the outlet at intervals during the oscillation of the oscillating body. Controlling the oscillation amplitude and frequency of the body, as well as the location of oscillating body outlets and frequency of fluid jet emission, have advantageous effects for the surface such as improved heat transfer properties and reduction in structural vibration and noise.

A fluidic device for providing analogue output control includes a main channel, a first control channel, a second control channel, a comparator which receives respective input fluid flows from the main, the first and the second control channels. The first control channel is configured such that the input fluid flow therefrom carries an oscillating pressure wave signal, the second control channel includes a flow regulator controllable to vary the mass flow rate of the input fluid flow from the second control channel, and the main channel is configured such that the input fluid flow therefrom is at a reference mass flow rate. The comparator is configured such that the input fluid flows from the first control and the second control channels act in combination on the input fluid flow from the main channel to produce an output fluid flow from the comparator having a PWM mass flow rate characteristic.

An aerodynamic flow control system includes a plurality of actuator units integrated at predetermined locations along a span of an aerodynamic surface of a vehicle to provide aerodynamic active air flow control, wherein each of the plurality of actuator units includes an electrically powered compressor to compress air; a transitional component to receive the compressed air from the compressor and provide two streams of the compressed air; and a fluidic oscillator having two inlet ports that receive the two streams of the compressed air, and an exit port that discharges a single oscillating flow of air at a predetermined velocity.