A system includes a surface, an actuator, and processing circuitry. The surface includes one or more non-actuating zones and one or more actuatable zones. The actuator is configured to a flow property of a fluid that flows over the one or more actuatable zones of the surface. The processing circuitry is configured to obtain a value of a parameter of the fluid that flows over the surface, and operate the actuator to adjust the flow property of the fluid that flows over the one or more actuatable zones based on the value of the parameter of the fluid.

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.

An airflow adjusting apparatus includes two or more airflow generators and a controller. The airflow generators are arranged in first and second directions along a surface of an object. The airflow generators are configured to generate respective airflows in parallel directions parallel along the surface of the object. The second direction intersects with the first direction. The controller is configured to control outputs from the respective airflow generators independently of each other. The controller is configured to cause a total output from the airflow generators in a first group to be greater than a total output of the airflow generators in a second group. The airflow generators in the first and the second groups are arranged side by side in an airflow generation direction. The airflow generators in the second group are adjacent to those in the first group.

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.

An airflow separation detecting method includes: applying an alternating-current voltage having a predetermined voltage value to a plasma actuator, the plasma actuator being disposed on a part of a surface of an object; and detecting that separation, from the surface of the object, of an airflow flowing on the surface of the object is occurring, in a case where an absolute value of a temporal variation rate of an electric power consumption value of the plasma actuator or an absolute value of a temporal variation rate of a current value of the plasma actuator is equal to or greater than a predetermined value, the temporal variation rate being a rate of variation relative to time, the electric power consumption value or the current value of the plasma actuator being measured under application of the alternating-current voltage having the predetermined voltage value to the plasma actuator.

An airflow adjusting apparatus includes an airflow generator, a state detector, and a controller. The airflow generator is configured to generate a control airflow to cause the control airflow to join an around-vehicle airflow formed around a vehicle body of a traveling vehicle. The airflow generator is configured to vary a flow direction of the control airflow with respect to a surface of the vehicle body. The state detector is configured to detect a state of the around-vehicle airflow. The controller is configured to vary the flow direction of the control airflow on the basis of the state of the around-vehicle airflow detected by the state detector.

A bonded body wherein functional base material is attached to object to be bonded. Functional base material and object are bonded with functional base material's end portion covered so operational effect neither lost nor adversely affected by fluid, bonded body has strong bonding property preventing functional base material peeled off due to weather. Peelability allows functional base material repair ease. Functional base material provided on object's curved surface to be bonded to along curved and/or smooth surface of object to be bonded to along smooth surface. Functional base material has peripheral side surface with peripheral distal-most end portion. Peripheral gap part provided between object to be bonded to and functional base material on inside of peripheral distal-most end portion and on side opposing to object to be bonded to. Peripheral gap part filled with holding member extending in laminar fan shape from peripheral side surface along curved and/or smooth surface.

Disclosed are methods and apparatuses for mitigating the formation of concentrated wake vortex structures generated from lifting or thrust-generating bodies and maneuvering control surfaces wherein the use of contour surface geometries promotes vortex-mixing of high and low flow fluids. The methods and apparatuses can be combined with various drag reduction techniques, such as the use of riblets of various types and/or compliant surfaces (passive and active). Such combinations form unique structures for various fluid dynamic control applications to suppress transiently growing forms of boundary layer disturbances in a manner that significantly improves performance and has improved control dynamics.

Systems and method for active control of stationary vortices for aerodynamic structures are disclosed herein. In one embodiment, a method for active control of vortices over a solid surface includes: generating vortices proximate to the solid surface; sensing locations of vortices by printed skin sensors; and maintaining the vortices in their fixed spanwise positions with respect to the solid surface by actuation of printed skin actuators.