Abstract: A method for determining flow properties of a fluid flowing along a surface by: modulating the current through a heating element of a thermal flow sensor located on the surface with at least one modulation frequency, thereby emitting a thermal wave into the fluid flowing along the surface having a penetration depth inversely proportional to the modulation frequency; measuring an amplitude of a voltage across the heating element at the third harmonic of the at least one modulation frequency, the voltage depending on the thermal conductivity and the volumetric heat capacity of the fluid flowing along the surface; determining a flow velocity at the penetration depth from the attenuation value of the determined amplitude of the voltage; and estimating whether the flow at the penetration depth is laminar or turbulent on the basis of the determined flow velocity. Also, a system and an aircraft with such a system.

Abstract: A drag reduction system an aircraft having an aircraft component is disclosed including a skin panel having an inner surface and an outer surface for contact with an ambient flow, the outer surface includes an upstream area for laminar flow and a downstream area for turbulent flow and/or transitional flow, the skin panel includes a plurality of micro pores for blowing air from inside the aircraft component into the ambient flow.

Abstract: A flow guide body for an aircraft includes a main body having an outer aerodynamic surface having a plurality of outlet openings, and flow control devices, each having an inlet, an interaction chamber, a first outlet and a second outlet. A first control inlet is connected to the interaction chamber at the first side of the chamber axis. The outlets are each connected to outlet openings in the aerodynamic surface. Each outlet has a control outlet. A second flow control device is arranged such that one outlet is connected with the inlet of the first flow control device. One of the control outlets of the first flow control device is connected to the first control inlet of the first flow control device, and the other of the control outlets of the first flow control device is connected to the first control inlet of the second flow control device.

Abstract: A vortex generator control system for a controlling an aircraft vortex generator arrangement comprising a controller configured to receive one or more deploy or retract command signals from a flight control unit and further configured to send one or more command signals to a fluid control valve, a fluid pressure sensor configured to sense one or more pressure values from an actuator of the vortex generator arrangement and to signal the pressure value(s) to the controller, wherein the fluid control valve is configured to control fluid transfer between the actuator and a reservoir in response to a command signal from the controller.

Abstract: A vortex generator arrangement comprising a section that defines an opening to a corresponding cavity, an aircraft airflow modification device disposed within the cavity, and at least one fluidic muscle actuator arrangement coupled to the airflow modification device.

Abstract: A method for active flow control of a fluid flow that flows along a flow surface includes generating a first local velocity field in the fluid flow by introducing a first vortex structure into the fluid flow by a first flow control actuator coupled to a first actuation site of the flow surface, and introducing a second vortex structure into the first local velocity field by a second flow control actuator coupled to a second actuation site of the flow surface located downstream of the first actuation site, when a head vortex of the first vortex structure has propagated with the fluid flow downstream the second actuation site.

Abstract: A flow body for a vehicle includes at least one planar skin section with an outer side, an inner side and at least one opening that penetrates the skin section, as well as at least one active flow control device that is designed for moving an air volume. The at least one active flow control device includes an air discharge section that is fluidically connected to the at least one opening, wherein the air discharge section and the at least one planar skin section are manufactured by a layer manufacturing process in the form an integral component that is free of joints, and wherein the air discharge section at least partially supports the skin section in a load-bearing fashion.

Abstract: An aircraft airflow modification device, comprising: at least one resiliently deformable base member; and at least one resiliently deformable flap member that extends from the resiliently deformable base member. Deformation of the resiliently deformable base member from a first state to a second state results in corresponding deformation of the resiliently deformable flap member from a first state to a second state.

Abstract: A flow guide body for an aircraft includes a main body having an outer aerodynamic surface having a plurality of outlet openings, and flow control devices, each having an inlet, an interaction chamber, a first outlet and a second outlet. A first control inlet is connected to the interaction chamber at the first side of the chamber axis. The outlets are each connected to outlet openings in the aerodynamic surface. Each outlet has a control outlet. A second flow control device is arranged such that one outlet is connected with the inlet of the first flow control device. One of the control outlets of the first flow control device is connected to the first control inlet of the first flow control device, and the other of the control outlets of the first flow control device is connected to the first control inlet of the second flow control device.

Abstract: A vortex generator arrangement for an aircraft, a flow control system and an aircraft comprising such vortex generator arrangement. The arrangement includes a surface portion facing a first region of space to constitute a flow surface, a vortex generating element, an element support structure connected to the element, a mounting structure. The element support structure and the element together are rotatable between first and second positions and a biasing device, retainer and release are provided. The rotational axis extends transversely with respect to the surface portion. The projection of the element onto a projection plane is smaller in the first rotational position than in the second rotational position, the projection plane extending perpendicularly to a tangent plane of the surface portion at a reference point of the surface portion and to a predetermined direction parallel to the extension of the tangent plane.

Abstract: Inter alia, an apparatus including a ramp, the ramp configured to enable variation of a cross section of a ram air passage of the apparatus. The ramp includes a first rigid member, a second rigid member and a flexible member coupled to the first rigid member and the second rigid member. The ramp is movably mounted at two ends. Moreover, a method of varying the cross section of the ram air passage of such an apparatus by moving the ramp of the apparatus is disclosed. Further, an arrangement including such an apparatus and a ram air channel communicating with the ram air passage is disclosed.

Abstract: An aircraft tail region including a cooling system installed in the aircraft tail region. The cooling system comprises a cooler, which forms a section of an outer skin of the aircraft tail region, and includes coolant channels allowing a flow of ambient air therethrough, and extending from a first surface of the cooler to a second surface of the cooler. The cooling system also includes a fan system, which is adapted to convey ambient air through the coolant channels of the cooler at least in specified operating phases of the cooling system, and a first opening, which is formed in the outer skin of the aircraft tail region, and which allows, in conveying operation of the fan system, ambient air which is supplied through the coolant channels of the cooler into an interior of the aircraft tail region to be discharged back into the aircraft environment.

Abstract: A vortex generator control system for a controlling an aircraft vortex generator arrangement comprising a controller configured to receive one or more deploy or retract command signals from a flight control unit and further configured to send one or more command signals to a fluid control valve, a fluid pressure sensor configured to sense one or more pressure values from an actuator of the vortex generator arrangement and to signal the pressure value(s) to the controller, wherein the fluid control valve is configured to control fluid transfer between the actuator and a reservoir in response to a command signal from the controller.

Abstract: A vortex generator arrangement comprising a section that defines an opening to a corresponding cavity, an aircraft airflow modification device disposed within the cavity, and at least one fluidic muscle actuator arrangement coupled to the airflow modification device.

Abstract: A vortex generator arrangement for an aircraft comprising a surface section forming a flow surface interacting with a flow surrounding the aircraft in operation, wherein the surface section comprises an opening, a vortex generator movable between a retracted position and an extended position, a retainer for holding the vortex generator in the retracted position, a biasing structure for biasing the vortex generator towards the extended position and a release for releasing the vortex generator from the retainer such that the vortex generator can be moved towards the extended position. Further, a sealing membrane is provided completely sealing the opening when the vortex generator is in the retracted position. The vortex generator is movable through the membrane from the retracted position to the extended position. Furthermore, a flow control system, an aircraft and a method of controlling flow are described and claimed.

Abstract: A vortex generator arrangement for an aircraft including a surface section, a flap element pivotable between a first position and a second position, a biasing arrangement biasing the flap element towards the second position, retaining devices retaining the flap element in the first or second position, and a release device releasing the flap element from the first retaining device. The biasing arrangement, the first retaining device and the second retaining device are configured such that the second retaining device automatically retains the flap element in the second position after the flap element has been pivoted by the biasing arrangement from the first position into the second position. As soon as the torque exceeds a predetermined value, the second retaining device automatically releases the flap element, which pivots against the force of the biasing arrangement into the first position and is automatically retained therein by the first retaining device.

Abstract: An aircraft airflow modification device, comprising: at least one resiliently deformable base member; and at least one resiliently deformable flap member that extends from the resiliently deformable base member. Deformation of the resiliently deformable base member from a first state to a second state results in corresponding deformation of the resiliently deformable flap member from a first state to a second state.

Abstract: A flow body for a vehicle includes at least one planar skin section with an outer side, an inner side and at least one opening that penetrates the skin section, as well as at least one active flow control device that is designed for moving an air volume. The at least one active flow control device includes an air discharge section that is fluidically connected to the at least one opening, wherein the air discharge section and the at least one planar skin section are manufactured by a layer manufacturing process in the form an integral component that is free of joints, and wherein the air discharge section at least partially supports the skin section in a load-bearing fashion.

Abstract: A vortex generator arrangement for an aircraft, a flow control system and an aircraft comprising such vortex generator arrangement. The arrangement includes a surface portion facing a first region of space to constitute a flow surface, a vortex generating element, an element support structure connected to the element, a mounting structure. The element support structure and the element together are rotatable between first and second positions and a biasing device, retainer and release are provided. The rotational axis extends transversely with respect to the surface portion. The projection of the element onto a projection plane is smaller in the first rotational position than in the second rotational position, the projection plane extending perpendicularly to a tangent plane of the surface portion at a reference point of the surface portion and to a predetermined direction parallel to the extension of the tangent plane.

Abstract: A vortex generator arrangement for an aircraft comprising a surface section forming a flow surface interacting with a flow surrounding the aircraft in operation, wherein the surface section comprises an opening, a vortex generator movable between a retracted position and an extended position, a retainer for holding the vortex generator in the retracted position, a biasing structure for biasing the vortex generator towards the extended position and a release for releasing the vortex generator from the retainer such that the vortex generator can be moved towards the extended position. Further, a sealing membrane is provided completely sealing the opening when the vortex generator is in the retracted position. The vortex generator is movable through the membrane from the retracted position to the extended position. Furthermore, a flow control system, an aircraft and a method of controlling flow are described and claimed.