摘要:
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).
摘要:
A flap of the type that is movably connected to an aircraft wing to provide control of an aircraft in flight includes opposite ends, wherein at least a first opposite end includes a plurality of substantially rigid, laterally extending protrusions that are spaced apart to form a plurality of fluidly interconnected passageways. The passageways have openings adjacent to upper and lower sides of the flap, and the passageways include a plurality of bends such that high pressure fluid flows from a high pressure region to a low pressure region to provide a boundary condition that inhibits noise resulting from airflow around the end of the flap.
摘要:
An apparatus for attenuating acoustic resonance generated by flow over a cavity in a surface comprises a plurality of flat flaps proximate to an upstream edge of the cavity. The flaps are disposed in an array spaced in a width direction of the cavity edge, and are oscillated by the flow in two degrees of freedom solely by the flow, independent of an actuation mechanism. Each flap includes a first hinge generally coextensive with the surface for enabling oscillation in a first degree of freedom and a second hinge orthogonal to the first hinge and forming a tab for enabling oscillation in a second degree of freedom. The hinges are constructed with torsional spring constants that provide predetermined oscillation frequencies and magnitudes. The apparatus can include a deployment mechanism for moving each flap between a stowed position wherein it is generally flush with the surface and a deployed position wherein the flap can be oscillated by the flow.
摘要:
A mast for connection between a power plant and the rest of an aircraft that includes an outside surface (14) that is in contact with the air flows, characterized in that it includes, in the outside surface (14), at least one recess (22) that is blocked by a porous wall (24), with a porosity of 3 to 6%, coming into the extension of the outside surface (14), whereby the recess makes it possible to have the high-pressure zone (18) communicate with the low-pressure zone (20), zones that are arranged on both sides of a shock wave (16).
摘要:
An oscillating vane actuator for active control of fluid flow over a surface includes a pivoted vane surrounded by a wedge-shaped chamber, and first and second conduits with openings adjacent the surface. The actuator also includes a rotating shaft with a connecting rod to actuate the vane in a oscillatory manner. As the vane travels in one direction, fluid is forced out from the chamber through the first conduit and opening into the fluid stream adjacent the surface, while fluid is simultaneously drawn in through the second opening and conduit into the opposite side of the chamber. Similarly, when the vane travels in the opposite direction, fluid is forced out through the second conduit and opening into the fluid stream adjacent the surface, while fluid is simultaneously drawn in through the first opening and conduit.
摘要:
A vortex generator may include a depression in an aerodynamic surface, and a vortex generator leading edge located in the depression. The vortex generator leading edge may include a leading edge upper surface. The leading edge upper surface may be positioned at or below a tangent line defined at a location along the aerodynamic surface upstream of the depression relative to an oncoming local flow.
摘要:
The invention relates to a body (10) having at least one surface (12) over which a fluid (30) can flow, said surface having a global course that defines a main flow direction (14) over the surface (12) at least partially has a structure for reducing a flow resistance of the body (10), the structure having at least one recess (16.2 . . . 16.3) provided with a substantially circle-segment-shaped cross-section for inducing a fluid eddy (26.2) . . . 26.3). The body is characterized in that the structure has at least one lead-in section (18.2 . . . 18.3), which is angled from the main flow direction in the direction of the recess (16.2 . . . 16.3) and which is arranged upstream of the recess (16.2 . . . 16.3) in the main flow direction, for leading a fluid flow (24) into the recess (16.2 . . . 16.3). By means of the structure, a fluid eddy (26.2 . . . 26.3) can be induced within the recess (16.2 . . . 16.3) and can be localized substantially within the recess (16.2 . . . 16.3).
摘要:
An aerodynamic body with an aerodynamic body surface that creates a contoured surface for a fluid to stream around, with a device to influence the flow of the fluid streaming around the aerodynamic surface. The flow-influencing device includes a passage to link the fluid streaming around the aerodynamic surface with an actuator space of an aspirating and purging device situated in the aerodynamic body, and an indentation that is situated next to the passage, which is formed by a recessed section of the aerodynamic surface on a flow-influencing region within the contoured surface of the aerodynamic surface, so that a boundary wall is configured as part of the recessed surface lying opposite the indentation. The aspirating and purging device can generate a swirl in the flow of the fluid streaming around the aerodynamic surface, the rotational axis of which is directed along the assumed aerodynamic body chord direction.
摘要:
Apparatus for controlling shock/boundary-layer interactions created by a supersonic shock on a surface of a structure, includes a cavity formed in the structure and having an opening on the surface. A plate is attached to the surface and covers the opening. A plurality of flaps are formed on the plate and is operable to cooperatively close the opening in response to subsonic airflow condition over the flaps, and open the opening to permit airflow through the cavity in response to supersonic airflow conditions over the flaps.
摘要:
An apparatus serves for influencing the separation of a flow 2 from a body 1 immersed in the flow. The apparatus excites a shear layer 11 of the flow 2 at the immersed body 1 by periodic blowing and suction in order to act against further separation of the shear layer 11 from the immersed body 1. For this purpose, the apparatus has at least one passive cavity resistor 46, the hollow cylinder 4 of which has at least one opening 6 leading to the surface 10 of the body 1. The cavity resonator 46 is excited by the flow 2 thus creating compressional vibrations, and the compressional vibrations of the cavity resonator 46 excite the shear layer 11.