The invention relates to an engine nacelle, including: a nacelle wall that has an inner side and an outer side; an inlet lip that is embodied at that end of the engine nacelle that is formed upstream; and an engine intake that takes in the air required for the respective engine and that is formed by the inner side of the nacelle wall. It is provided that the nacelle wall includes an air-permeable structure that extends from the outer side to the inner side of the nacelle wall, and that is configured for passing air that flows against the outer side from the outer side to the inner side. The invention further relates to a method for influencing the flows inside an engine nacelle.

A vertical tail unit (7) for flow control including: an outer skin (13) in contact with an ambient air flow (21), wherein the outer skin (13) extends between a leading edge (23) and a trailing edge (25), and surrounds an interior space (29), and wherein the outer skin (13) includes a porous section (31) in the area of the leading edge (23), a pressure chamber (15) arranged in the interior space (29), wherein the pressure chamber (15) is fluidly connected to the porous section (31), an air inlet (17) provided in the outer skin (13), wherein the air inlet (17) is fluidly connected to the pressure chamber (15), wherein the air outlet (19) is fluidly connected to the pressure chamber (15). The vertical tail unit (7) has reduced drag and an increased efficiency because the air inlet (17) is formed as an opening (35) in the outer skin (13) at the leading edge (23).

An aircraft structure (11) for flow control including a perforated panel (13) having an inner surface (15) directed to a structure interior (17), an outer surface (19) in contact with an ambient flow (21), and a plurality of micro pores (23) connecting the inner and outer surfaces (15, 19). Elongate crack stopper elements (25) are attached to the inner surface (15) of the perforated panel (13). The crack stopper elements (25) are configured to inhibit crack propagation within the perforated panel (13).

A method of providing active flow control for an aircraft includes cooling a liquid coolant in a heat exchanger by circulating a cooling airflow through the heat exchanger, and providing fluid communication between the cooling airflow and a boundary layer flow of at least one flight control surface of the aircraft. The cooling airflow affects the boundary layer flow of the flight control surface(s) to provide active flow control. A method of cooling an engine core of an engine assembly includes circulating a cooling fluid through the engine core, and cooling the cooling fluid with a cooling airflow used to provide active flow control to a flight control surface of the aircraft. An active flow control system for an aircraft is also discussed.

A panel for an active laminar flow control arrangement may comprise a longitudinal wall and one or more division walls extending from the longitudinal wall and extending between the first end and the second end. The panel may be coupled to a nacelle outer skin via a plurality of adhesive fasteners pre-installed onto an inner surface of the outer skin and onto stiffeners and/or stringers associated with the outer skin.

A noise attenuation element can be arranged for connection to an air directing structure such as a wing flap. The element has a non-uniform lattice density across at least a portion of the body of the element.

An airfoil for flow control is disclosed having an outer skin in contact with an ambient air flow, wherein the outer skin extends between a leading edge and a trailing edge with two opposite lateral sides, and surrounds an interior space. The outer skin comprises a porous section in the area of the leading edge, a pressure chamber arranged in the interior space and fluidly connected to the porous section, an air inlet fluidly connected to the pressure chamber, and an air outlet fluidly connected to the pressure chamber.

Variable-porosity panel systems and associated methods. A variable-porosity panel system includes a panel assembly with an exterior layer defining a plurality of exterior layer pores and a sliding layer adjacent to the exterior layer and defining a plurality of sliding layer pores. The variable-porosity panel system additionally includes a shape memory alloy (SMA) actuator configured to translate the sliding layer relative to the exterior layer to modulate a porosity of the panel assembly. The SMA actuator includes an SMA element configured to exert an actuation force on the sliding layer and at least partially received within an SMA element receiver of the sliding layer. The SMA element extends out of the sliding layer only at a sliding layer first end. A method of operating the variable-porosity panel system includes assembling the variable-porosity panel system and/or transitioning the panel assembly of the variable-porosity panel system among the plurality of panel configurations.

Sound absorbers and airframe components comprising such sound absorbers are disclosed. In one embodiment, an airframe component comprises an aerodynamic surface (48) and a sound absorber (38). The sound absorber (38) comprises a perforated panel (40) having a front side exposed to an ambient environment outside of the airframe component and an opposite back side. The panel (40) comprises perforations extending through a thickness of the panel for permitting passage of sound waves therethrough. The sound absorber (38) also comprises a boundary surface spaced apart from the perforated panel. The boundary surface and the back side of the perforated panel (40) at least partially define a cavity in the airframe component for attenuating some of the sound waves entering the cavity via the perforations in the perforated panel (40).

The propulsion system for vessels comprises at least one suction sail (3), said at least one suction sail (3) comprising a suction system (10) and a transmission unit (8) to drive the rotation of said suction sail (3), wherein the suction sail (3) comprises at least two suction zones (7) arranged symmetrically on two sides of the suction sail (3), said suction zones (7) comprising variable suction means.

It provides a propulsion system for vessels that allows reducing their fuel consumption and polluting emissions by using an improved version of suction sails.