An aircraft wing has an upper surface element and a first actuator powered mechanism for varying the shape of the surface element which includes: an upstream segment SEG.sub.1, a downstream segment SEG.sub.2, an interconnecting segment SEG.sub.3 interconnecting a downstream edge of SEG.sub.1 with an upstream edge of SEG.sub.2, wherein the interconnecting segment SEG.sub.3 extends along the whole or at least a major part of the downstream edge of SEG.sub.1 and the whole or at least a major part of the upstream edge of SEG.sub.2, and a link element LNK interconnecting an upstream edge of SEG.sub.1 with an upper surface of the aircraft wing, and the first mechanism interconnecting a contact C1 on a lower side of the upper surface element with a contact C2 on an inner structure of the airfoil. The first mechanism controls the shape of the upper surface element by controlling the distance between C1 and C2.

In one embodiment, an airfoil includes a first side and a second side opposite the first side, and an apparatus coupled to the first side of the airfoil, the apparatus comprising a first edge having a first uneven edge pattern.

A blade for a fan of a turbomachine, for example of unducted fan type, a corresponding fan, and a corresponding turbomachine. The blade includes a mechanism arranged, at a single location, to locally, as the fan rotates, disturb a distribution of flow around the blade so as to form two independent main vortices downstream.

Thermal actuation of riblets is described herein. One disclosed example apparatus includes a riblet defining an aerodynamic surface of a vehicle. The disclosed example apparatus also includes a thermal expansion element within or operatively coupled to the riblet, wherein the thermal expansion element changes shape in response to a surrounding temperature, to displace a movable portion of the riblet relative to the aerodynamic surface to alter an aerodynamic characteristic of the vehicle.

A device to reduce turbulent flow skin friction uses carbon dioxide, riblets, and suction holes to reduce the overall drag of a body moving in a fluid. A deflector (2) pushes up the boundary layer of the incoming flow on a surface (1). Carbon dioxide is injected into a plenum (3) and ejected through an exhaust slot (4). Riblets of specific dimensions (5) are placed to interact with the carbon dioxide flow that is now the sublayer viscous flow. After passing the riblets, the flow is sucked partly through suction holes (6), preventing flow separation that could increase the form and wave drag.

A flow interrupting device may cause a flow to separate from a wingtip device at a desired angle of attack. The flow interrupting device may be coupled to a leading edge of a wingtip device where a flow disruptor may be configured to alleviate a load on the wingtip device. The flow disrupter may comprise an edge that extends into a boundary layer at a threshold angle of attack that may disrupt the boundary layer and cause a flow to separate from the wingtip device. This separated flow may reduce stresses experienced by the wingtip device and wing during various flight conditions where a transverse flow is encountered.